gleKtor 010000 · 2019. 7. 18. · series in stock. Ask for full list. if sockets n cn 7 03 43 LOD...
70
February 1986 gleKtor 010000 UK £.1.20 USA $3.60 IR £.1.92 (incl. VAT) Active aerial with SMDs Artificial intelligence Designing a closed loudspeaker box 1
Transcript of gleKtor 010000 · 2019. 7. 18. · series in stock. Ask for full list. if sockets n cn 7 03 43 LOD...
February 1986
gleKtor010000
UK £.1.20USA $3.60
IR £.1.92(incl. VAT)
Active aerial with SMDs
Artificial intelligenceDesigning a closed loudspeaker box 1
ht.
EEFebruary 1986
116991 Cs cry s s4 -5313.
7403 0.9901 033749 0.307403 0337404 0.3335
749 0796 00.4040.
7407798 0.97409 0.337410 0-307411 0.307412 0337413 0507414 0.707416 0.367417 0.40749 0-30
1. 00.9507423 036749 0407426 0.407427 097428 0.437433 0307432 097433 0337437 0.30749 0.407439 0.40790 0.407441 01074425 0.7074434, 197444 1.107445 1/074464 1.0074474 1.007449 1.037450 0.367/51 097453 097455 0.9790 0957470 OW7472 0.467473 067474 097475 0607476 0.467483 0.657431 1.807.93.4 1.974544 19749 1.10749 0.42749 2.107494 0.97431 0.7074324 0.7070325 097494 1.107195.4 0.60795 0971433
2-11.900
74107 05074103 0.7574110 07574111 0.5574115 1.7074118 1.1074113 1.7074120 11074121 0.974172 07074123 0507413 0.667419 0957419 0.974132 0.7574135 07074141 09074112 2.5074143 2.7074141 2.7074146 1.1074147 1.7074148 1.407419) 1.75741514 0.7074140 03774154 1.407419 05374155 0974157 0937419 1.75741E0 1.1074151 02074162 1.107419 1.1074164 19741E5 1-1074165 1.4074167 4.0074170 20074172 42074173 1.974174 1.1074175 1.0574176 1.0)74178 1.974179 1.507983 1.0074181 3.4074132 1.4074194 110741364 13074193 1.3)74191 1337419 1.1074193 1.1574194 1.1074195 09374195 13374197 1-107419 2207419 2-97491 1.1074251 110
1.9174997429 02074273 20371276 1.4074278 1.7074279 0.9374283 1.9742E6 3974250 097493 0907429 111374351 2 -CO74394 0974394 0.00743674 0974394 0.7071.375 1.607479 1.10
743937449743SO7491
1.201.101201.40
/44S SERIES74150) 0.24741931 024741522 0247999 0.24711504 0.247499 0.24741.503 0.2474903 01474910 02474911 0.24741512 0.24711513 0.3479914 037741515 024741520 0.2474191 0.24741522 024741524 093741525 0.24741527 0-2471193 0.2474193 0.2474159 024741533 0.2479537 0.2474939 0.2471159 024741.642 0.50741547 0913741.59 010711551 0_247994 0.2474955 0.24741579 010749744 015741.55 0.45741994 0.36741.579 0.42711. SEDA 0.79741.540 0.75749E6 0357990 0.48741591 0.90741532 09741.533 054741998 0.75741596 0_90915107 0.40749109 0.40749112 0.45749113 0157415114 0.45741.592 0.10799123 09749124 1.97495125 09074919 0_9719132 0.40749133 051374199 0.67415138 09749133 097415145 0_957115147 1.5749142 1.40749151 0.567415152 2037415153 065749154 1.507419155 0.65741519 0.9749157 097413158 097.9.51604 0.757415161A Q757415194 0.757119634 0757415164 0.75741511354 133741.51665 15074919 13)74/5159 1.00749170 140741.51735 103749174 0.75749175 0.75749181 203749183 1.93749130 0.75741.5191 0.757415192 12807415193 0107419944 0.75711.51564 0.757415196 OM7415197 09749221 093749240 0.90749241 0.917415242 0937415243 0.907415244 0.9374996 1.107415247 1.10741949 1_107415249 1.10749751 0.75749253 0.757415256 0.9074152574 0.707415:e84 0.707415256 12074929 0957415261 1.2074152E6 0.9379.5273 1.25749273 0.7074929 5.9)7415283 080749990 0_8071/9292 9.0374990 0_97415256 1.407415297 9.007415238 1.007415259 2237415231 3.70749323 1037415324 397419343 2107415352 1.2071L5353 1.974995 2-107415353 197115354 193749365 0-50741539 0.507415367 415274939 0_507 0.9041973719374 090749375 015719377 1.979.5373 0.95
7415379 13374991 4.50711593 0.607.115393 1.037415-4 1.037415339 1.407415445 1.83741549 12)7419467 1.83741993 1.9741554) 1.00741696 7.037415610 19.00749612 19.037495E24 3.5074199 2_257415623 22574993 1.97415640 21074156401 3.00741591 1.50749642 2507415619 3537419643 29741.5643-1 3.00741994 350749615 2.0374156.15.1 4.0074969 0.9371199 09749670 1.7079591 2-50741591 3.93711597 3507499 6.00740423 65074095 6_5074M5 6.50
4403 SERIES4901:1191219942074)034009401040119112431391440154316431743184319.4=42214924021924aoas43264077923409193343314094033A:G4
10359374,394039404000414042943
4954016401794840499504351409405340549.6596494394400340354057409497403349940709719724073975407540774376961962409ices993493435440E6956197
493A.31 0-361632 0.55493 0.946.9 0164526 310496 0.904E99030 094533 120910 0$51511 0564512 0.554513 1.504514 1.104515 1.104516 0554517 2234519 0.484519 0.32459 0.604521 1.15492 0104575 0.70469 0.80459 0.9459 1.00tat 0.75
0240250.700250.830.60.600.24090.360.60
0.360.70
0.90.90.600930.600.700330.480-240.930.400.500.750.91.031.32500.702001.101.002.500.900590_500.190.91.030500600.90.360350.560.40.400.80083
4.030.700_850.40
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0.30.600.7512130.90.930.900-932_7D0.75093
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4594724 13314411 7.5014412 7.5014415 1001919 2.6014493 4.2014995 4.501900 6.501639 20322100 3.5072101 7.032292 7.0300014 0.454095 1.9997 0,3640398 091090 19043101 11543102 1.5134,319 20340104 1.940105 1.5040116 0.489107 0.554019 320919 12040110 2_340114 21540147 25303153 1109173 12040174 1.0340175 1004019 1.039193 1.0043114 1.03929 1.504945 1.94097 1.6043373 1,933974 1.9)8395 0.980097 0 75E30513 0.75
Full rangeof 74S Et74HCseries instock.Ask forfull list.
if sockets
n cn 7 0343 LOD
TTl & Eel -
A0791 12034000503 1193494791000 25.00
431-9050 1.00A33 -E010 4.50AY3-3910 1934333912 510C.430194 1.0391.30254 1.10CAXI46 0.70CAX69 320943353 393CA3'Rr9 0.93CA339 0.93CA33933 29CA32 3.75CA3/30'E9340 030CA31307 133CA31405 0.6C43110T 1.10CA3146 29CA3150E 150CA3161E 2.03CA31621 610CA3189_ 170CA3295 19CA371397, 1030902 6.000AC19059 100DAC039 3.03D49008 393DC33213 3.03H51340 1.9)10913 6.7599511 091C17560 4.0319.790 2501C19333 4.001C7.172169 22501947217 7.501947535 0.90951796 1.40
197120 3.03LC7133 300LC7431 3501C7137 3.509347 1201.7351 0.93LEM 0.99355 0101.9559 1.101937 1.039110C1H 4.5391001A 0.33151307 0.45Lscacecn 0.75161310 2259,1311 0.03
'1315 1.50_9319 1.839924 0.45
1.151.33
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-'.343 0.633.600.50
Ltean 3001193939-8 1.50919011 19311,139149 1.701M7E2 20011953 3-99934 2.201.699691 13791337 2.70191329 19011,991 1.501613929 1.10114.373 0.9154354CH 4911.375 0.3
VOLTAGE REGULATORS14 FIXED VOLTAGE PLASTIC 10220A. - VS5 V 795 0.45 7945 0.506 V 7336 050 7346 0508 V 798 09 7938 093
12V 7812 0.46 7912 0.915 v 7215 050 7915 09018 V 7818 09/ 7918 01021 V 7024 0.50 7324 0.93IA FIXED VOLTAGE PLASTIC 7042
5 V 7916 0106 V 73106 098 V 75108 033
12 V 73112 010OTHER
15 V 7915 0.95 V 7319 0.46
12 V 751)2 0915 V 17115 050
SWITCHINGREGULATORS REGULATORS1.69.59 1.40Ort3221: 1507SHOCCC5 A 5 'V 5.75771312 6.4078935 5.
it H1.1919 1501-1917K 240LM2077 2-999537 4.00LM -L459 1510
99 2_535'9,91 30317.451 3.0319.17 3.0373393 2.539419 1.53
REGULATORSLNITZN 0_5079940 6507909 2979119C 6.757931170 250791019 1.40
OPTO ISOLATORS
11074MC/25M192403Lap=70111
1 111112 0.702.20 9.113 0.70tco elms 0.70190 69137 31019 91139 1.350_70
DISPLAYSEN *9 100 MA6910 203910930911791.00 74555581 5.7057405071111.729 900 111311 850691179131701 1.00 711.732 157MAN7111)1707 100 T1179 1.03104343510 1.75 1.14155910 9507.1A144610 210
DISPLAY DRIVERS9368 4919370 4 50193914 350193915 350943315 15003/16119 3.9110961214 320U192003 050
U:2121104 03)ULNXIM 29301 47802 1.9311192073 1.83956299 1.9025431 0.10799 040
OTHERS2145777 0.50BPX25 1.835991 293
P 1
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120
1.9120
1.51710 0.481),1711 19311923 0.6019172501 3.1991733 06591741 02294747 0.701.1945 0.30941011 4.50911014 15011.11931 1001141330 250191871 10311.111172 310191196 6.031/6199 4.931.142917 3.19193902 09smasco 0.5099309 110metro leo193314 3911,13315 3.401143315 3.401913833 1.91,1515131 2.3)1915161 4.50193712 20013C1310 1.9MC1413 0.751101458 0.4659119- 3.03791496 0.701403343 20379391 0-70693433 0.56691091 4.10595910 9.03511(9339 11.0019-90 51054139 4.0359952214 10)NMI 12097999 022999 0.939964 4.109E665 1239955 1509957 1.25*4E570 40311E571 399932 0_931335322 1.50
ero9.6939 19114 1.4
12071935319 1.93OP -09P 350P1.1.94 5.00RG419 0.9401151 203R041% 993R0492 0.95569 2.20557243 9.00519 99 16.03SF -96364 &CO5143) 3.95196339 19stinote 4105696195 4.009576660 1205937992 7.03TA7120 120
1.40747204 1.50TA7X6 0.931499 1.50TA7310 15094231 1_20194900 093T3A1310 0.93784520 09
0.7579993 210
191(9 537TCA210 39070.4220 3.50TC4910 1.751341010 215TO41022 450904194 1.1070411235 300TDA2002 3.3TDA2003 1.93939004 240T3A2006 320TDA2320 3.9TDA290 2.507043310 7.50104739 3.501941032 7.03TLC61C.P 0.911-1312 0.831964 0.9011.91 0.4011.072 0.7015.074 1.101191 03511.C62 0.559083 01571081 1.0311.094 2.91119 050994109 9 9.341479 323052242 12094.41713 1.7049.9.18314 4.03411/12C034 0951.11.1999 0751.11172053 29U1142502 193ut.tasca 1.80U9239 110070576 2.75UP95994 203UPC11591 3,9UPC11911 5.07XR710 491492206 4.03X997 3.75X22211 5.75X22215 6.75XR229 1.202904 1032914 09321919 1.751.423E 1.3399245 1.33294259 3.50914259 3.9194.7758 6.03Z94259 4502942959 2.929-149 /009149.5 3.03Z714505 7.927149CP 10321310145 2.9211193 6.1099139 733791.494E 9.50
C Pu s
18329 6.5326534 10.50902 4.50EE0322.MHz
903994 5.5066328 8.039.0 25092 3.0369 12.3.2 999 6.50939 10.0391309 1000
ATTENTIONALL PRICES ARE
SUBJECT TO CHANGEWITHOUT NOTICE
SCRS LOW PROF144135 SOCKETS BY TEXAS
sac4 8.03cesace 120393918 36108335 1938095 610B39 42)8.193 710EICEGA 420994 1C0119554 7.5089 22039E9 17.50EMI 12008713 16 CO34,454097 14.9317155395 1200292834 2902E03 5.299 75070D -R 7.50(CMOS 7301
201E950 4.002101 4.00902 35021078 5.0021114 35 4002114-3 250
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1505.00
616116193 40352649 15 4009151E90
.911.5074715231 3.50745256 2-993415 603937,123 7.505743 690
RONts PROMS
4 co21510 2501909 200tecAcao 2.0374519 1.9745287 225745233 1.97/5317 2258293 1.5082519 1_509513 1.75
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CRTCONTROLLER
CR15077 16.109111569 9.039939 8539339 2595996 25.00559367 3603M0945 5.501.105294P 6.9/95347 6.5059994 8.0319.59918 900
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IX CONNECTORS
CRYSTALS I.:TERFACEg ICS
32 79 1.19 1.03 A00613 20401_00 MHz 270 A07531 15371 5/32 MHz 2.25200 MHz 275
400330346125.510
11.903.50
245760 119355203
2.5 MHz 29/26621.IHz 7_503./2 619 1.753 276 M11, 1503.5795 /99 1934 z 1.404.194 5119 1_50413 MR, 1004.99 5139 2934 9152 MHz 2035 09 1.1144 150598 1.756 03 61147 1.406_14949 1.40703 1,09 1.507.759 119 1.758 03 Wiz 1.5081671419 11510.9 MRS 1.75)0$)114: 2.5010.70 1114 1.9190 MHz 303903 MHz 15014_03 MHz 1.7514318799 1.6014.75994 2501500 MHz 2.031610 kW/ 2-0317.731 M9 1.5018371191 1.3018432 MHz 19131959119: 1.50X3032 51114 1.752499 Milt 1.5043.03 14.9 135116149 250PX01000 129
DISCCONTROLLERS
8.037654 109)3272 1203931771 9.03F01791 2003F131793 903513197 22909132733 27.03992797 27.0399191 15.034x02113 1203
CHARACTERGENERATORS
50.3-251300750
RO-3-313117.03
REAL TIMECLOCK
5963119 4.03Gt....eau-tan 9.9016.69332R51.50
BAUDRATEGENERATOR
61 14411 7509319116 61047023 150
KEYBOARDENCODER
43.5.976 11 50419-3500 7.537992 5 CO71923 610
UHFMODULATORS6 MHz 3.755 MEN 993SOUND *09519112 11,9. 1203
4.994-526213.9345175925323509439-531 12357,ak532 120A4179139 99D932 613cmcact-cal-V
26.000100131 600DP3334 350053911 350058930 1.4005591 190055932 150DSEE33 225osaate 1.5005933 2.3MC1433 0.60MC 0.03619455 29319319 4_93MC3470 4.757594913 8.93593-95 215MC3/87 2_916494 5.5079944 5_501614411 9.03MC14412 7.509417)3 0.7575107 emntoe 0.9s7519 12375110 0.9075112 1.6D75113 12075114 1.4075115 1.915121 1.4075122 1.4075150P 12175154 1.207519 2.20ma) eoo75161 15375162 4.4075172 3.0075112 090751E3 0.6075189 ,6007539 1975051 0509919 05075453 0.7075154 070?aim leo-ism &as75292 0165126 1238125 12099 120
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TELETEXTDECODER
5445020 6 95445333 700549941 16 CO544.5.75) 900
DARTS
AY 3.10152 103A3-610132 30700143317 300119432 4-
1141E WRAP 50C -1E1550 TEXAS
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9099904 1450 175p 2009 2204 235P
Remo959 1254 1500 1609 1109 2009
EdgeCeee 1200 135p 299 3204 3404 905
E URO CONNECTORS
Pog SocketD IN 41612 2 - 32,59 33)p 35044919 2 3299 35134 939949 3 3299 904 -[for 2-32 995999 a- 999 913114 11617 2199 18)p 1659Din 41617 31 *ay 170p 17040:772 32 e47 9 ?4I - 934 77542 32 was 9-9 99 _ _ 279p 32353 3249_. 9 PSI 30043 32 way Ana P9.-- 40241 DC Skt A -84254For 2 32 991999 974670 441041`9IA - 8.A -03
MAIL ORDERS TO: 17 BURNLEY ROAD, LONDON NW10 1EDSHOPS AT: 17 BURNLEY ROAD, LONDON NW10
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1934T1P41C114142A 60471199TIF47 9041994 1r;TIPS9419 70911199 9340799 70p214219 3504992154 324293229 30427994 3342925462939.1 3092/23C63 3542930E1 604
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MIN DCONNECTORS
..5i oar 77 .11 33VALE
642 E. Tap 233 414119 1 I00 2.00 13:0
33 1147 *30 2Seo 5X4872e4 1 fee 152 294p 44:0 -mt..=wie 0-411 54 33 120 10:0 -3 wer Cmcr.. i't= Leer. 1 91 psock
Camme. 1,04 Cern30 75 way 4,418 194 949 4544 -
PLEASE .%1111) 511p p&p & 15':.(Export: no VAT. p&p at Cos)
Orders from Government Depts. & Colleges etc. welcome
Detailed Price Last on requestStock items arc normally bx return of 991
NSA=NM
Satellite aerialP. 27
Car alar-P 62
5 Editorial8 News and views
43 Letters
ELECTRONICSTECHNOLOGY
17 Electronically controlled cameras -a close look at the innards of a Minolta 9000
27 Satelite TV receiving equipment - offering analternative to BBC and ITV programmes
57 The future for artificial intelligence - how willfifth generation computers affect our daily life?
59 The accordion image sensor - Philips scientists aredeveloping a new type of solid-state image sensor.
68 Designing a closed loudspeaker box - a simplifiedapproach to hi-fi quality sound reproduction
We regret that, owing to circumstances beyond ourcontrol, Opto-electronics in practice has beenpostponed indefinitely.
PROJECTS22 DC operated battery charger - how to
charge NiCd batteries from a car battery
30 Active aerial with SMDs - a simple butuseful introduction to working with surface -mount devices
32 MSX Extensions - the second article in thepresent series describes an add-on cartridgeboard
49 Graphics card - the concluding article dealswith the colour extension board
62 Car burglar alarm - an alarm that can only bedisabled by a four -digit code
70 RF circuit design - this first of a short seriesof articles looks at making a test oscillator
Graphics card -6p.49
INFORMATION39 Corrections; 40 Make your own PCBs; 42 NewLiterature; 44 New Products 73 Infocard; 74 ReadersServices
GUIDE LINES25 E E shopping page; 56 Buyers guide; 67 Appoint-ments; 75 Switchboard; 76 Classified ads;76 Index of advertisers
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February 1986Volume 12Number 130ISSN 0268/4519
In ourMarchissue An active
sub -woofer Universal printer
buffer The Bohm
synthesizer 8 mm video RF circuit design:
VHF filters Electronic tem-
perature control Light work for
sub -marine cables
EE
February 19E64
40 Disc Lockable Box
BBC Micro Computer SystemOFFICIAL DEALER
ACORN COMPUTER SYSTEMS:B3C B PLUS with DFS E369BBC B PLUS with 128K E389P.BC B PLUS Econet INo ()ESL E360BBC B PLUS Econet Et DES E39933C Dust Cover E4.50
fa)(a)(a)fa)(d)
UPGRADE KITSAcorn DFS K¢030 (dl 1.2 OS ROME7.50Econet Kit ...E55 (c1) ONES ROME17.50 (dlAcorn DFS KitE80 WI 12 OS ROME7.50 (dl_corset Kit .. (55 Id) ONES ROI:117_50 (dlBASIC II ROM with User Guide --172-50 Id)1770 DES upgrade for Model B .43.50 (d)ADFS ROM (for B with 1770 DFSft B plus) £26 (dl
Ei4K Upgrade Kit for B plus E35 (dl
WORD PROCESSOR ROMSVIEW . E41 IdVIEW 3.0 E69 (c)HI VIEW f36 (c)VIEW INDEX EIO id)WORDW1SE f28WORDWISE PLUS £42 Id)WORDEASE (24.50 (dlSPELLCHECK III E31 (dlUTILITY ROMSDISC DOCTOR 124 Id)EXMON II E22 idlREPLICA III £12.50 Id)TOOLKIT PLUSPRINTMASTER . ......ACORN GRAPHICS ext. ROM
DATA-BEEBLA
ACORN ADD-ON PRODUCTS: BCPLZ80 2nd Processor £299 (a)6502 2nd Processor £169 (b)Teletext Adaptor E125 (a)IEEE Interface £278 (b) ROMs available!ri addition to products fisted above we stock a wide range of BBC peripherals including:TORCH UNICORN products. GRADUATE the add on that makes the BBC micro IBM compatthle.TIME WARP Real Time Clock, Colour Graphics Plotter. Graphics Tablet, Video Digitiser, EpromProgrammer etc.'-arge selection of business pleasure and education software including CPM software far the AcornSind Torch. Z80.r-cr detailed specification of any of the above ec_ write or telephone.
. E33 Id)E23 (dl
E22.50 (dlCOMMUNICATION ROMSTERMULATOR .. .. . E25COMMUNICATOR £49 (dlCOMMSTAR £20 (dl
f22 (dl
BCPL CalculationsBCPL Stand Alone GeneratorISO-Pascal/Logo
£46 Ibl£17.30 (dl
122 (dl£46 (dl
Please write or telephone for detaas of other
DISC DRIVESSingle Drives:' 400K 80/40T DS :TS400 E99 Ibl
Dual Drives: (with integral psul Stacked Versiors.D200 2 x 100K 40T SS f195 (al
PS403 with psu
PD800P 2 x 400K
(120 lb)
£199 lay
3.5" Drives:The mechanisms are 130 track double sided and are capable of both single and double density:peration.T535 1 x 400K 80T DS £39 Ib) TD35 2 x 400K 80T DS E172 lb)
3M FLOPPY DISCS
AUTHORISED 3M DISTRIBUTORDATA RECORDING PRODUCTSIndustry standard floppy discs v.ith a life time guarantee. Discs in packs of 10:
5% DISCS40T SS DD... £13 (dl 401 DS DD... £18SOT SS DD....£22 (dl SOT DS DD... EN Idi
3'A DISCS831 SS DD... £30 id,
DS DD £38 id,
DRIVE ACCESSORIESSMg,e Disc Cable £8.50 (di10 Disc Library Case £1.80 Icy 30 Disc Storage Box E6 (el
E16Floppiclene Drivehead C" .9 Kit with 20 rf cleaning kits £14.50
Ell (dl Dual Drs.; Cable
£14 Icy 100 Disc Lockable Box
PRINTERSEPSON: TAXAN KAGA:RX8OT £169 la) KP810 £229 (alRX100 £306 I a) KP310 £339 (a)LXSO 1209 (a) JUKI: 6100 £279FX80 E299 (a) BROTHER:JX80 4 colour £435 (a) HR15(111 £285 (a)H180 Plotter £345 la) HR15LX (Serial) £365 (a)We hold in stock a large variety of printer attachments, interfaces and C047-sufnabl. Please write or phone for details.
ACCESSORIESBUFFALO 32K Buffer for Epson printers E75 101, FX80 plus sheet feeder E129 lb);EPSON Serial Interface: 8143 En Ibl: 8148 with 2K buffer E57
EPSON Paper Roll Holder E17 FX80 Tractor Attach £37 lb): RX/EX80 DustCover E4.50 LX130 Tractor Unit E20 Icy.EPSON Rthbons: MX/RX/FX80 £5: MX/RX/FXI00 110 (dl: LX80 E6 Idl:
JUKE Serial Interface £65 WI; Tractor Attach. an (a): Sheet Feeder £182Ribbon 12.50 (al.
BROTHER HR15: Sheet Feed (189: Rakers - Carbon or Nylon (4.75; MuttistaeE5.50 Id); 2400 Sheets Fanfold with extra fine pert. 9.5" - C13,93; 15" E17.93 lb).BBC Parallel Lead E8: Serial Lead E7
BT APPROVED MODEMSMIRACLE 3000:A new range of microprocessor bas: offering speeds of upto 2400 baud, full duplex.Features include 'HAYES' protocol
'
c ay, auto answer. auto dial, speed buffering, printerport, data security option etc. Mains powered .WS3000 V2123 (V21 Er V231 E295 (a)WS3000 V22 las above plus 1200 baud full duplex) £495 WIWS3000 V22 bis 2400 (as above plus 2403 baud fug duplex) 13350 layMIRACLE 2000A world standard modem covering. V21. V23 IBA 1031113/1013 outside UK) and including 75, 300,400, 1200 baud ratings Optional Auto dial, auto answer cards, complete control from computerkeyboard WS2000 E125 Iblauto Dial Card E30 Id) Auto answer Card E30 (dlSKI Software Control Kit E10BUZZ BOX: Pocket size, creed connect 300/300 half and full duplex with originate and answermodes E55 (c/Data Caries for above moderns atadable for most computers.
ALL PRICESEXCLUDE VAT
is viva' 0,10 art.difi,
a.k.a./a kirkiws
011'8 lblt2 50 (01'150 (dif100
PROJECTS:Junior Computer KitHousekeeper kitBektemfhal KG 113801ASCII Keyboard kit
£86 Ibl£56 lb)£50 lb)E75
J C Becks 1, 2, 3, & 4E6.90 (C) E.3Universal Terminal (6602)Kit E75 Ib)
Bekterrn'nal Kr, (ISEG( £70 lb)
MONITORSMICROVITEC 14" RGB1431 Standard Resolution £185 ial1451 Medium Resolution £2251441 Hi Res 1365 falMICROVITEC 14" RGB/PAL Er Audio1431 AP Standard Resolution . £199 fat1451 AP Median Resolution .. £275 (alMITSUBISHI 14" RGB IBBC It IBM)Medium Resolution E229 dal
-TAXAN KAGA 12" RGB (BBC Sr IBMIVi ion II (210 (alVision III plus . )a)SuperVision Ill (330 lay
12" MONOCHROME MONITORS.SANYO.DM8112CX Hi Res Green E 86 la'
TAXAN KAGA:KX1201 MI Hi Res Green EtchedScreen E 92 (a'KX1203 Hi Res Amber EtchedScreen £105 la.
PHILIPS:7502 Green Screen E 75 la,7522 Amber Screen E 79 la,
SOFTY IIThis low cost intdugent eprom programmercan program 2716,2516, 2532, 2732, and withan adaptor. 2564 and 2764. Displays 512 bytePage on TV - has a serial and parallel I/Oroutines. Can be used as an emulator. cassetteinterface.Softy II £195.00 lb) Adaptor for
7764'2564 E25.00
TECHNOLINEVIEWDATA SYSTEM
Tel 01.450 9764Using 'Prestel' type protocols.
For information and ordersavailable 24 hours. 7 days
a week
PRODUCTION PROGRAMMERSGANG OF EIGHTThis is a smart, fast programmer with an audible a!arrn arid a 'conversational' 1;qu'dcrystal d,st-/sy. Single key operation discourages mistakes wit/ut performing BLANKCHECK, VERIFY and PROGRAM functions autornatiry. Programming voltage selec-table 12.5/21/25 V. we.' program all popular 5 V singie rat eprccrs. It wt program8 epnarrs at a tine E395 lay
P9300 Range:These new range which will handle ALL current 5 V single8 eproms at a time comprises of three following models:A21 models have 16 character display. 10 different fault detection features v automaticsea test. 16 bct programming capabirty and a selection of high speed programminga'gorithms:P9)10: A low cost duplicator £795 (a)P9320: With serial interface with 8 different formats and 8 K buffer lexpardsble to32 KI £935 (alP(X0: Top of the range with serial interface with 16 formats, baud rate upto 19.2 K,8 K expandable buffer, editing functions. Printing faddy, remote control from acomputer E1236 la)EP9100This CPU contreeed. Emulator Programmer is a powerful tool for both Eprom program.thing and development work. EP13030 can emutate and program at eproms up to8K x 8 bytes, can be used as smrxleone unit for editing and duplicating EPROMS.as a stave tamer -am -nu Cr as an eprom emulatorE695.00
enrorns and copy
UV ERASERSUV1T Eraser with buit-in ti-ner and mains inicator. Bust -in safety interlock to avoida :4i:dental exposure to the harmful UV rays. It can hancre up to 5 morns at a time withan average erasing time of about 20 mins £59 + E2 p&p. UV12 as above but withoutthe tuner E47 + f2 p&pFor Industrial Users, we offer UV140 Er UVI41 erasers with hand tug capacity of 14aproms. UV141 has a butt in timer. Both offer fun butt in safety features UVI40 E61,UV141 179, p&p (2.50
PROGRAMMED ROMS FOR ELEKTORPROJECTS
503-N Jr.!. Computer Monitor27E8 f 4.80
504 Disco lights 2706E 4.80505 Chess Intc)ekt 2.2716 £14.63506 J C Tape Monitor .... 2716 E 7.30507-N J C Printer Mon & PME
2716 f 7.33508 J C Bus Control 82523 £ 4.80510 153 MHz Freq Meter 2 x 82523
£ 9.50514 Dark Room Computer 2716. £ 7.30
516 Talking Dice 2716 £ 7.30521 CharGen & Video Routine for DOSJunior 2732 + 2716 (16.40522 CharGen & video; Routine fcr ex'tended junior 2732 + 2x 7716 124.03523 Char. Generator 27M E 9.00524 Cluantisizer 2732 E 9.00525 LIOnsesal Term. 2732 f 9.03526 Wind Ds Ind 7716 f 7.30527 E3abyrienti 2716 f 7.33533 Dasywiv-e:.-I (face .... 2732 f 9.00
SEE OUR INSIDE FRONT COVER PAGE ADVERTISEMENT FOR COMPONENT PRICES
riFA 1,T10MAIL ORDERS TO: 17 BURNLEY ROAD, LONDON NW10 lED
SHOPS AT. 17 BURNLEY ROAD. LONDON NW10(Tel. 01 208 1177. Telex: 922800)
305 EDGWARE ROAD. LONDON W2
PLEASE: A111) 50p p&p &15"..I.V1*(Lxport: no VAT. p&p at Costl
Orders from Government Depts. Er Colleges etc. welcome.Minimum telephone order 15.Detailed Price list on request.
Stock items are normally by return of post.
Editor: Len SeymourAdvertisement manager: S BrooksPublished by:Glentop Publishers LimitedStandfast HouseBath PlaceHigh Street, BarnetLondon EN5 lEDTelephone:
Editorial:(01) 441 4130Advertising: 102271 66106
Telex: 22828A Kluiser Group CompanyManaging director: K BorlandOverseas editions:Elektuur B.V.Peter Treckpoelstraat 2746191 VK Beek - the NetherlandsEditor: P E L KersemakersElektor sariRoute Nationale; Le Seau; B.P. 5359270 Bailleul - FranceEditors: D R S Meyer:G C P Raedersdorf
Elektor Verlag GmbHSasterfeld-Stralle 25100 Aachen - West GermanyEditor: E J A KrempelsauerElektor EPEKaraiskaki 1416673 Voula - Athens - GreeceEditor: E XanthoulisElektor Electronics PVT Ltd.Chotani Building52 C, Proctor Road, Grant Road (ElBombay 400 007 - IndiaEditor: Surendra lyerElektor JCEVia Rosellini 1220124 Milano - ItalyEditor: D FumagalliFerreira Et Bento Lda.R.D. Estefania, 32-1°1000 Lisboa - PortugalEditor: Jorge GoncalvesIngelek S.A.Av. Alfonso XIII, 141Madrid 16 - SpainEditor: A M FerrerInternational co-ordinatingEt technical manager:K S M WalravenInternational editorial secretariat:M J M Lacroix; G W P WijnenThe circuits are for domestic useonly. The submission of designs orarticles to Elektor Electronics impliespermission to the publishers to alterand translate the text and design,and to use the contents in otherpublications and activities. Thepublishers cannot guarantee toreturn any material submitted tothem. All drawings, photographs,printed circuit boards and articlespublished in Elektor Electronics arecopyright and may not be repro-duced or transmitted in any form orby any means, including photo-copying and recording, in whole orin part without prior written permis-sion of the publishers. Such writtenpermission must also be obtainedbefore any part of these publicationsis stored in a retrieval system of anynature.
Patent protection may exist inrespect of circuits, devices, com-ponents etc. described in thismagazine. The publishers do notaccept responsibility for failing toidentify such patent or other pro-tection.Distribution:Seymour Press Ltd., 334 BrixtonRoad, London SW9 7AG.Copyright 1986 Elektuur B.V.
Printed in the Netherlands by NDB,Zoeterwoude.
February 1986
Towards a common opennetwork standard?More and more users - and prospective users - ofcommunicating machines, irrespective of whether theseare robots, computers, telephones, or a mixture of them,are envisaging networks that comprise machines of dif-ferent makes. There is a common belief that when thisbecomes possible, markets will expand more freely,because competitive power will then not be dependenton which particular manufacturer a dealer is tied to, butrather on the price, function, and performance of themachines. Most users are, understandably, in favour of acompletely open network, i.e., one that will allow anymake of equipment contained in it to freely exchangeinformation with any other make of terminal attached toit.
There is a snag, however, or, rather, there may be. Thesuccessful interlinking of different makes ofcommunicating machines requires an internationallyaccepted standard. The International StandardsOrganization - ISO - is developing a general data-
communications standard called Open StandardsInterconnections - OSI - which, it is hoped, will eventu-ally facilitate the linking of, for instance, computers fromdifferent manufacturers. However, and here is the possiblesnag, IBM, which dominates the world market formainframe computers (IBM and IBM-compatiblecomputers account for over 80 per cent of the worldmarket), has its own system for connecting in computers,called Systems Network Architecture, SNA. Some 20 000SNA networks are already fully operational.
Competitors of IBM, fearing that the SNA standard mayfurther increase IBM's share of the market (and therebyreduce theirs) are already cock -a -hoop with OSI,although this will not be fully defined for quite sometime yet.
Although IBM, like other industrial giants, is used toproprietary standards, which can be made to force usersinto buying only their products, it is carrying outresearch and development on OSI. In fact, last October itbrought out a local area network - LAN - that is fullyopen to other makes of equipment. Moreover,spokesmen for IBM have on several occasions recentlyreiterated IBM's backing of OSI. Cited is, for example, thevalue-added network - VAN - that IBM will operatewith Japan's NTT, and which will have to accommodateNTT's open standard as well as SNA.
At present, these developments look encouraging, and,sceptical though we may be, we must hope that thebasis of a common interlinking standard will be agreedsoon.
EEFebruary 1986
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WATFORD ELECTRONICS250 High Street. WATFORD. WD1 2AN. Herts
MAIL ORDER Er RETAIL SHOPTel. (0923) 37774 TIx. 8956095 WATFRD
All Devices Brand NEW Er Fully guaranteed. Send Cheques. P.Os. Et Bank Draft cor ACCESS/Master Charge Et VISA card number with order. Government Et tEducational Establishments' OFFICIAL orders accepted. P&P add El to all Cash Iorders. Overseas orders. postage charged at cost AIR/SURFACE.PRICES SUBJECT TO CHANGE WITHOUT NOTICE AND AVAILABLE ON IREQUEST.
VATEman enders ro VAT. UK customers ca .e add 15% VAT to the tOtal o-dee costre/ pEtp We Cock thousands mare items a pats 1p vizi: us_ Nearest Urderground -Bn
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177: 270 247. 401/.. 1511. 27 9P: 33 124: 330. 473 324: IMO 484: 2200 904: 25V: I 5. 4 7,10.72. 47 e5, 1E0 lip: 15012p; 221157: 337224; 470 254.6E0. 10(0344: 1500 424; 2303504. 3300 76p:47C0924, 16V:47.68. 1009p; 12512p: 33)164-.47020p: M0344: IC(0 274; IMO 317: 26:0 Mo. 4700E794.
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POLYESTER RADIAL LEAD CAPACITORS, EA V FEED -THROUGH10%, IS,. 27n 6p. 33n. 47n. 66n. 103n 84: 150n. 2X11 Ito; CAPACITORS3331. 4201 154. 690n 194: lu M.14. 14.6 404: 212.467.10071E 457'. 104
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POLYSTYRENE CAPACITORS:'Oa to 1r.F 84, 15nf to 12nF lop
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See Sti.1 Cwoluzotd Bead 454
PRESET POTENTIOMETERS0.1W 100R MAR 1.1reatureVertemt or eio,zento so025W IKR3 i77R Ha-zon, 124.075W MR 4.7412 serr.cal 12p
SILVER MICA (Vases m 4E12. 33. 17. 82. 10.12.15. 18. 22. 27. 33. 38. 47.50. M. 63. To. M. 85. 100. 120. 150. 1E045
154 each2M, 220. MO. 270. 303. 330. 360. MO, 470, MO.833 214 eachWOO. 1200. 18:0. 2200 334 each:3300, 470355 Wp each
MINIATURE TRIMMERS Capacitors.2 64F. 2.I065 224. 2.MpF, 5.834F 334: 10-M,,"354
RESISTORSminiature Carbon Fiirn 141. -Stab. 5%
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safety switch. £30111 SPARE 'UV lamp bulb 113
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BBC MICROWORD-PROCESSING
PACKAGE compete v:ordpeocessing pac-kage consisting of BBC Micro.Zenith Green Hires Monitor.twin cased mot: Disc Drives.
Wordy:foe. Watford's DFS inter-face. Brother 14R15 Dais-Nye/leerprinter, Database package. 10
Discs. al manuats and cables.An you recpthe is a mains power
point to have it up and running.
Only: £999
SPECTRUM 32K RAMUPGRADE KIT
Upgrade your 16K SPECTRUMto 48K. Full fitting instructionssupplied. ONLY: £18
ACCESS/VISAOrdersJust phone yourorders through.We do the restTel: 0923 50234
V75.4
51/4" DISK DRIVESfor the BBC Micro
(All Drives are supplied cased withPower Supply and Utilities Disc)
CS100 - TEC Single 100K. 40 track, -7 e sided E105 CS200 - Epson Single 203K. 40 track, Double sided (107 CS400S - Mitsubishi Single 4013K, 80T. Double sided
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8
VIEWS NEWS VIEWS NEWS VRevised IECstandard forpot coresThe International Elec-trotechnical Commission- IEC - the authority forworld standards in elec-trical and electronicengineering, has pub-lished a revised standardfor the dimensions of pot-cores made of magneticoxides and associatedparts. This third edition -133C - incorporates thesecond, published in 1967,and specifies dimensionsthat are of importance formechanical inter-changeability for a pre-ferred range of pot -cores,and the dimensional limitsfor unwound and woundcoil formers to be usedwith them.
Second awardfor TonyChapmanAfter being awarded ashield for excellence in in-ternational sales and ex-ceptional customerservices over a period often consecutive years bythe Micro -Tel Division ofAdams Russel of Baltimore,USA, in October, TonyChapman Electronics
Limited of Epping, Essex,was in Novemberawarded first prize in theLondon regional final ofthe National SmallBusiness Efficiency Awards.The photograph showsTony Chapman, manag-ing director of TOE (centre)being presented with theaward by Sir AnthonyJoliffe, president of theLondon Chamber of Com-merce and Industry, whoorganized the regionalcompetition, and Mr BrianRigby, chief executive ofBritish Telecom.
BritaindominatesnationalvideotexWith western Europe's lastmajor videotex contractbeing awarded to Britainby Italy, over eighty percent of national videotexnetworks are now usingBritish technology.SIP, the Italian nationalcommunications authority,has placed a £25 millionorder for the software ofPrestel, the UK videotexsystem, and computersfrom GEC, Britain's largestelectrical goods and con-tracting concern.There are now national
Advanced computer software and equipment that willprovide a real time an- picture covering an area of fourmillion square miles at command and control centreslocated in hardened bunkers throughout the UnitedKingdom is undergoing final testing before being in-stalled as part of the improved UK air defence groundenvironment (IUKADGE) The photograph shows (1 to r)Flight Lieutenants Robert Andrews and Robert Gullick ofthe RAF with two Marconi displays (left) and a Plesseydisplay (centre). The large image in the background inproduced by the Hughes Aircraft Company HDP-4000Large Screen Display. The contract for updating Britain'sair defence network was won by UKADGE SystemsLimited (UKSL), jointly owned by Marconi, Plessey, andHughes.
videotex networks in sixwestern Europeancountries: Britain, Italy,Austria, the Netherlands,France, and FederalGermany. The first four useBritish technology.Other nations using the UKsystem are Australia, NewZealand, Malaysia,Singapore, and HongKong.Videotex allows owners ofadapted TV sets to use apush-button keypad tocall up information heldby central computers ontotheir screens. Data is trans -
miffed along telephonelines.The computers typicallystore news, sports fixturesand results, share andcommodity prices, foreignexchange rates, weatherreports, traffic information,and train and airlinetimetables.Prestel, the pioneer system,began in 1979. In Britain, itwas at first used almostentirely by businesses, buttoday forty-five per cent ofthe 60 000 TV sets that canreceive the service are inprivate homes. TL:LPS
9 EE
February 1986
WS VIEWS NEWS VIEWS NEWS VHigher qualityelectroniccomponentsA new process whichcould dramatically im-prove the performance ofmachinery that automati-cally assembles electroniccomponents has beendeveloped by PrestwickCircuits of Irvine in Ayr-shire, the largest producerof printed circuit boards inEurope.The company says that itsnew boards will becomeavailable early this year,and will offer much higherquality and reliabilitythrough components pro-duced by the latest high -volume productionmethods.Over the past year or so,the electronics industryhas begun to move awayfrom the traditional pinconnectors and over toautomatic assembly bymounting componentsdirect onto the surface ofthe circuit boards. How-ever, difficulties havearisen in making goodsolder joints between thecomponents and the cir-cuit tracks, which hasresulted in a high faultrate and expensive re-working of completedboards.A spokesman of thecompany said that twonew processes are beingadded to the productionsequence of boards. Thefirst removes the problemof outgassing, in which ex-traneous material from theboards can contaminatethe solder joints. The otheris a second plating pro-cess which improves theconsistency of the surfacesand makes it easier to at-tach solder masks. In thisway, a more reliable con-tact, particularly withsurface -mount compo-nents, is produced.Over the past five years,the company has invested£20 million in automatedproduction equipment.
Already major suppliers toGeneral Motors and Ford,the company is using itsnew process to spearheada marketing drive in theUnited States. With auto-mobile components in-creasingly being stan-dardized for world-wideuse, Prestwick Circuits seesscope for a significant ex-pansion of its business inthe US. CL:LPS
Automaticspeechidentification ofmulti -channeltest monitoringA novel technique to aidmulti -channel monitoring
of engineering tests byautomatically identifyingthe inputs from a largenumber of sources hasbeen devised by theNational Nuclear Corpor-ation -NNC.In situations where inputsare collated in groups onmulti -channel taperecorders, operators up tonow have had to speakidentification codes ornumbers onto the tapes foreach group of channels.This is open to two sourcesof error: the operatorcould make a mistake, ordamage to the tapecould make recordingunidentifiable.NNC has removed thisuncertainty by using aspeech synthesizer thatwill automatically identifythe signal groups andrepeat the identification
The complete engineering test monitoring rig andsynthesizer identification facility. The synthesizer itself issituated at the top of the first bay on the let?, while thetape recorders and signal filters are towards the right ofthe picture Also visible are spectrum analysers and thecomputer tht controls the engineering test monitoring.Photograph by courtesy of the National NuclearCorporation.
every five seconds.NNC is responsible for thedesign of the nuclerisland of the AdvancedGas Cooled Reactors-AGCR- at Heysham andTorness. As these stationsnear completion, a com-plex series of engineeringruns will be performed onthem. These will bemonitored to assess theperformance of the stationequipment. The tests werestarted at the first of thetwo Heysham reactors lastNovember.Schematic representationof the test monitoring rig isshown in the diagram.
Fibre opticcommuni-cations onnational gridA fibre optic communi-cations system is being in-stalled on a large sectionof the national grid by theCentral ElectricityGenerating Board. As partof the grid's refurbishmentprogramme, the opticalfibre links are being in-stalled in the earth wireswhich run between thetransmission towers.The aim is to establish acommunications trianglethat links the boardcentres in the south-east,the midlands, and thewest of England. The links,operating in conjunctionwith microwave radio, willbe capable of carryingspeech and data.There are two main ad-vantages to the Board ofthe new system - securityand economy. The newlinks will enable the Boardto have total control overits own in-house oper-ational communicationsrequirements. Cost savingswill arise when the Board'sown system is used as analternative to other com-mercially availablesystems.
EEFebruary 1986
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WS VIEWS NEWS .1 VIEWS NEWS V:
Airlinertelephones in1987?Satellite communicationsfor aircraft will start to be-come a reality next year.From then on it will bepossible for passengers tomake calls from airlinersto any part of the worldand crews will have bettercontact with the groundand other aircraft.The London -based Inter-national Maritime SatelliteOrganization -INMARSAT-has formally decided toalter ifs charter so that itsnetwork of satellite com-munications for ships canalso be used by aircraft.INMARSAT says the serviceit plans to offer airlines in-cludes data links for thetransmission of airline op-erational, performancemonitoring, meteorologi-cal, and other information.Such links would also per-mit the locations of air-craft to be monitoredwhile a voice servicewould be included tohandle telephone calls.The organization has beenworking with the Inter-national Civil Aviationorganization -ICAO- andother airline organizationson the project. A numberof trials and demon-strations have alreadybeen staged to prove thefeasibility of the service.A major airline will takepart in further trials, in-cluding passenger tele-phone service. This willalso involve equipmentmanufacturers andtelecommunicationsauthorities.The number of ships, oilrigs, and other offshorestructures now using theINMARSAT satellite systemhas increased from about1000 in the late 1970swhen the service beganto almost 4000.The present system usestwo Marecs satellitesleased from the EuropeanSpace Agency, four
Drug supplier Graham Tatfard & Company has a drugordering system in which their retail pharmacies haveEpson HX-20 computers linked to a central system 2500for ordering and delivery. Further information from.- TedHarwood. telephone Bracknell (0344) 282924.
maritime communicationssubsystems aboard Intelsatsatellites, and a Marisatsatellite leased from Corn -sat General of the USA.INMARSAT, which is a con-sortium of 44 membercountries, recently orderedthree of its own satellitesat a cost of well over £100million; the first of these isdue to be launched in1988 as the start of asecond -generation systemwith greatly increasedcommunications capacity.The new spacecraft willbe equipped to operatein part of the aeronauticalfrequency band. JFW:LPS
Low -currentlithium cellAn AA -sized 3 -volt lithium -manganese -dioxide cellrecently announced byVenture Technology ofAbingdon provides areliable high -energy -density power source forlow -current -drain appli-cations, in particular as aback-up power supply forvolatile computermemories. It is claimed tobe completely safe underall normal conditions, in-cluding short circuit, andto be very tolerant ofabuse.The LiM 145S cell measures15 mm dia. by 50 mmhigh, and has a capacity
of 1800 mAh whendischarged at 1 mA orlower currents at 25 °C.The cell is available witha variety of terminations tofacilitate direct mountingon a printed -circuit boardwith solder tags or pins, aswell as contact free forpressure connection.Like other cells in VentureTechnology's 3 -volt LiMrange, the 145S containsno toxic chemicals and isclaimed to be among themore benign of the lithiumsystem. It can therefore besafely used in equipmentcarried on the person.
Young elec-tronicsdesignerawardsThe Young ElectronicsDesigner Awards Schemeis aimed at helping toease the shortage ofsuitably skilled graduatesand school leavers whoare available for recruit-ment, and also the lack ofrelevant commercial skills,which is often experi-enced among those whoare recruited.The world's largest manu-facturer of semiconductors,Texas Instruments, whosesubstantial British -basedoperations, in common
with other employers, havefelt these problems forsome time, has joined theindustry newspaper Elec-tronics Times and compo-nent distribution groupCirkit Holdings PLC(originators of the scheme)to provide challengingnew incentives. These aredesigned to encouragethe inclusion of practicalelectronic projects in thecurriculum and includeequipment and materialsfor educational establish-ments taking part pluscash and career develop-ment opportunities forstudents. Its implemen-tation in the academicsphere is being spear-headed by Professor JohnEggleston, Professor of Edu-cation at Warwick Uni-versity.All projects entered will bejudged by a panel of ex-perts at a series ofregional previews nextmonth, and the winners inthe three categories (agegroups under 15; 45-18;and 19-25) will be an-nounced at a specialevent in May.
Peter van Cuylenberg.Managing Director ofThxas Instruments, is seenhere explaining the oper-ation of a TI Business ProComputer -a prize for thesuccessful educationalestablishment in the seniorcategory of the YEDAScheme- to Ken Warren,MR Chairman of theCommons Select Com-mittee on Trade andIndustry (centre), andProfessor John Eggleston,Professor of Education atthe University of Warwick.
EEFebruary 1986
WS VIEWS NEWS VIEWS NEWS IT:
ICL contract forTelematicsTelematics International ofBasingstoke have an-nounced a five-year multi-million pound agreementfor the supply of its NET25product line to STC Net-work Systems within ICL.The contract covers thesupply of packet switchingequipment, network man-agement, and controlsystems, as well as sup-porting services andspares. The marketing ofX.25 data networks rein-forces ICL's commitment tostandards and especiallyto OSI (Open Systems Inter-connection).Established in 1982,Telematics InternationalLimited designs, manufac-tures, and markets highperformance communi-cations processor systems,providing applicationsolutions in host front -ending, network switch,management and accessproducts where highthroughput, program-mability, and high re-liability are of primeimportance.
Atlas echosounderThe Atlas Deso 20 surveysounder has been de-
signed for shallow anddeep water applications,providing not only ac-curate data of waterdepth, but also detailedinformation on the bottomstructure, such as sedi-ment, layers, and wrecks.The unit, which isavailable for hire from GSERentals (Luton and Aber-deen), is seen here in atypical installation onboard a vessel.
Airborne radarfor AustraliaHelicopters being built bythe US Sikorsky Companyfor the Royal AustralianNavy are to be equippedwith Super Searcher air-borne radar systems fromMEL at Crawley under acontract worth more than£5 million.Super Searcher is an ad-vanced command andcontrol 360° radar de-signed to be the core of acentral tactical system -CTS - or as a stand-aloneradar. It does this by col-lating information from theinternal sensors of the air-craft and external sensorsprovided by other aircraftor ships.Among its many roles,Super Searcher can carryout anti -ship, anti-submarine, air -to -surfacemissile control, andsurface-to-surface missile
Agfa-Gevaert, Europe's largest reprographics companyrecently launched its sophisticated Computer AidedRetrieval -CAR- system in the UK. In CAR, thecomputer is paired with microfilm, the leading mediumfor storing analogue information. The result is an infor-mation management system of unrivalled power and flexi-bility. The photograph shows the CAR workstation, whichcomprises a DEC mini computer with hard -copy printer,lockable film storage cabinet, and Copex LK16 microfilmreader -printer
control roles.Incorporating the most up-to-date microprocessortechnology and one ormore colour TV rasterdisplays, the system caninterface with sonar,conics, and ESM (elec-tronic support measures)equipment by displayingdirect onto the TV rasterdisplays. It has both activeand semi -active missileguidance capability. (LPS)
New IEC guideon safetyrequirementsThe first edition of Guide105, Principles concerningthe safety of equipmentelectrically connected toa telecommunications net-work, is now availablefrom the International Elec.trotechnical Commission(via the British StandardsInstitute).The guide offers advice onhow to protect operators
from hazards in electricalwhen it is con-
nected to a telecom-munications network. Itwas developed by the IECin close co-operation withthe International Telecom-munications Union - ITU.The goal of the twoorganizations was to en-sure that standardization iscarried out in ways thatwill allow InformationTechnology standards andcommon technicalspecifications applicableto telecommunicationsnetworks to contribute tothe efficiency of infor-mation exchangesthroughout the world.
ELECTREX '86ELECTREX '86, the 23rd in-ternational electro-technical exhibition, isbeing held at theNational Exhibition Centre,Birmingham, from 24 to 28February.
February 19: Ill
WS VIEWS NEWS VIEWS NEWS V:
Super neutronmachine willspeedmaterialsresearchThe world's most powerfulmachine for probing thestructure of matter hasstarted to produce new in-formation about the com-position of basic materialssuch as crystals, metals,and glasses.The new £100 million fa-cility, officially known as aSpoliation Neutron Source,or SNS, has been built atthe Science and Engineer-ing Research Council's(SERC) Rutherford AppletonLaboratory near Oxford,and is destined to be-come the most importantinternational equipment ofits kind over the next 18months as it works up tofull power.The giant machine, whichtook seven years to build,was designed to produceshort but very intensebursts of neutrons. Theseare one of the elementarybuilding blocks of matterand are considered a realtool for wide-rangingstudies of the properties ofmaterials at atomic andmolecular levels.Neutrons are normally ob-tained for such scientificresearch from nuclearreactors, but the SNS pro-duces them by a differentmethod that involves aseries of accelerators inthe release of neutrons.Once freed, they escapealong tubes where instru-ments measure the inten-sity of neutrons scatteredfrom the material underinvestigation.The SNS, which was for-mally inaugurated byMrs Thatcher on 1 October1985, has been named Isisafter the river that runsthrough Oxford: it is alsothe name of the Egyptiangoddess of fertility.Mrs Thatcher, herself a
scientist, said some areasof industry were showinginterest in using the newfacility, which is alreadythe subject of workingscientific agreements withFrance, Federal Germany,Italy, Sweden, and otherEEC states. JFW:LPS
Electric spacepropulsion planScientists believe spacesatellites of the future willuse a new type of electricpropulsion rather than thechemically fuelled rocketsof today.Satellites currently usechemical rockets to main-tain their position in orbit,and communications sat-ellites stationed over aparticular part of theearth have to make anyminor positional changesto correct the effects of thesun and moon and otherdisturbances in space.The problem withchemical rockets is thatthey require the satellite tocarry 200 kilogrammes ormore of chemical pro-
pellant to fuel the rocketsover the operational life ofthe spacecraft.Research has shown, how-ever, that this mass of fuelcould be reduced sub-stantially by the use ofwhat is known as electricpropulsion. This takes theform of thrusters that wouldpropel space vehicles byproducing a jet of high-energy particles by elec-trical acceleration.Plans are under way todevelop such an electricpropulsion system thatcould be used on many ofthe 300 satellites that arelikely to be put into orbitaround the earth betweennow and the year 2000.The work is being led byscientists at the fusionresearch centre atCulham, Oxfordshire,where earlier research hasalready shown such asystem is feasible.Under a nine -monthgovernment research con-tract, the team will ex-amine particles of xenon,krypton, and argon gasesas the fuel source forthrusters. Mercury andcaesium were tested inprevious prototype
The new $8 million General Electric Automation Centre,opened last October and occupying 1600 m2 in a modernbuilding close to the heart of Frankfurt in West Germany;will be used as an application, training, seminar, anddemonstration facility for the company's automationcustomers throughout Europe. The photograph gives apanoramic view from the operator's station showing, fromlei? to light: laser pallet station; automated manhouse BTAHL 1000 automated guided vehicle; Mandell Regent 1001and Series Six master control console.
thrusters, but presented therisk of contaminating ordamaging the spacecraft.By contrast, the new gasesare inert, so will neithercontaminate nor damagethe craft.With the new system, posi-tively charged ions areproduced in the rocket byionization of the pro-pellant by electron& Theions are then acceleratedto high speeds by electricfields and ejected at avelocity of up to 40 km i s,i.e., ten times that of theexhaust from a chemicalrocket. JFW:LPS
Three outrightwins forBICC-VeroBICC-Vero took first pos-ition in all the categoriesin which it was mentionedin Techpress' recentlypublished brand
preference study. Thismajor research documentinto the UK electronicsmanufacturing industry isan authorative indepen-dent guide to the purchas-ing attitudes and esteemin which suppliers areheld. The high ranking at-tained by BICC-Vero showsthat it is either dominant,or a leading supplier, inits product sectors.One of the first positionswas for most informativeliterature, samples ofwhich are shown in thephotograph.
EEFebruary 1986
WS VIEWS NEWS VIEWS NEWS V:
British TV pro-grammes forEuropeancable viewersAn 18 -hour daily trans-mission of the best ofBritish TV programmes tomillions of cable viewersin western Europe andScandinavia moved astep nearer last Novemberwhen the IndependentTelevision Companiesdecided in principle to goahead with the Super -channel Satellite Service.The British BroadcastingCorporation is at presentdiscussing with the in-dependent companies tobecome a programmesupplier to the new ser-vice, which would befinanced by advertising.According to the Indepen-dent Television CompaniesAssociation -ITCA- thenew technology is open-ing new markets, and theyfelt that agreement wouldbe reached with the BBCon providing a servicefrom late 1986, whichwould offer British TV pro-grammes to millions ofEuropean cable viewers,including breakfast shows,sport, and news.Britain has sixteen in-
dependent companiessupplying TV programmesand a final decision onthe number of them takingpart will lie with individualboards. Formal approvalof the Independent Broad-casting Authority -IBA-will also be neededbefore the venture canstart.An existing satellite will beused to relay signals tocable and satellite masteraerial TV -SMATV- oper-ators in Europe who willnot be charged for theprogrammes, which willbe supported by Pan -European advertising. LPS
Satellite accessfor EurovisionBritain's televisioncompanies are now ableto exchange programmeswith their Europeancounterparts on a dailybasis by the use ofsatellites.The change -over from settime transmission on theEurovision microwave ter-restrial radio link to directaccess via satellite followsa deal concluded last Oc-tober between British
7bcmars 60 Mbyte fast rape back-up system for the IBMPC, XI,' A7,' and compatibles. Further information from:Tina Boylan, P7'4' Gt Portland Street, London WIN 51-IG.Telephone: (01) 388 4832.
Telecom International, theBritish Broadcasting Cor-poration, and the In-dependent BroadcastingAuthority. This gives bothbroadcasters direct con-trol on satellite transmis-sions via a dedicated TVlink to the earth satellitestation at Madeley (Staffs).A spokesman for BritishTelecom said that thededicated line to theEutelsat I -F2 satellite wouldgive broadcasters greaterflexibility in setting up pro-gramme exchanges withEurope such as news itemsand sports events, andalso provide a facility formultiple destinationbroadcasts.The European Broad-casting Union controlcentre in Brussels will con-tinue to be responsible forco-ordinating Eurovisionsatellite transmissions,although broadcasts willno longer have to berouted through the centrefor onward destribution.The Eurovision network wasestablished in 1954 tofacilitate the exchange oftelevision broadcastswithin Europe. In its firstyear, the network carriedfifty-five transmissions; thisfigure has steadily grownto 14 000.The European Broad-casting Union has leasedtwo transponders on theEutelsat I -F2 satellite forEurovision. IncludingBritain, six countries nowhave access to thesatellite for Eurovision ser-vices. LPS
Straight factson scienceJournalists throughout theworld are being offered afree briefing service bymore than a thousandscientists resident in Britainwho have agreed to par-ticipate in the Media
Resource Service -MRS.The facility, launched bythe Ciba Foundation -anindependent charity- lastOctober, is being providedfree of charge. It aims atimproving links betweenscientists and journalistsand thereby the quality ofinformation which thepublic receives on mattersof world-wide concern.Leading scientists, underthe chairmanship of SirPatrick Nairne, Master ofSt Catherine's College,Oxford, formed a steeringcommittee to establish theservice. Its patrons includeseveral well-known figuressuch as Sir David Atten-borough, the naturalist; SirMonty Finniston, the indus-trialist; Sir Bernard Lovell,the astronomer; and SirHerman Bondi, the mathe-matician and spacescientist.Dr Christopher Langley, theMRS's information officer,will receive calls between0900 and 1700 (British time)from Monday to Friday,with an answerphone forqueries received outsidethis period. On receivinga call, Dr Langley will con-sult a register containingthe names of more than1000 experts who haveagreed to take journalists'queries. Information willbe provided either on abackground or on an at-tributable basis accordingto the arrangement madebetween the journalist andthe scientist.A recent survey of theBritish press showed thatup to 10 per cent ofnational newspaper storieshad a major medical,scientific, or technologicalcomponent.The Ciba Foundation,which has been operatingfor over forty years, de-cided to back the MRS,because it believed it vitalthat public debate onsuch issues as AIDS, acidrain, and the StrategicDefence Initiative shouldhave a proper scientificbasis for meaningfuldiscussion. LPS
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WS VIEWS NEWS VIEWS NEWS V:
The Societe Internationale de TglecommunicationsAeronautiques -SITA- has placed an order with Philips7blecornmunication and Data Systems for the supply of 15SOPHO-NET nodes, initially valued at £2.2 million. Thecontract was signed by the Director General of SITA.Mr C Lalanne (seated left) and Mr J Pelgrom, chairman ofthe executive committee of Philips's Telecommunicationand Data Systems (seated right). With them are the SITAand Philips executives involved in the negotiation andspecification of the contract.
UK setshumiditystandardWhat are the tolerances ofmicroprocessors and otheradvanced computerizedprocessing instruments toatmospheric moisture?That question andnumerous others concern-ing humidity can beanswered by two newmachines at the NationalPhysical Laboratory -NPL-at Teddington, which pro-vide industry with anational standard hu-midity measurement.The measuring of moisturein the air is important tomany industries, includingelectronics, electricitygeneration, food, phar-maceuticals, paper, tex-tiles, aerospace, and gas.It is also important in con-trolling the environment infactories and publicbuildings, and is, ofcourse, extensively used inweather forecasting.NPL's interest dates from1980 when they commis-sioned SIRA, a scientific
company, to charry out anindustrial survey to deter-mine the requirementsand economic justificationfor a national humiditystandard.Costing £500 000 and fiveyears' work, the twomachines provide a basisfor all traceable calibra-tions of humidity measur-ing instruments in Britain.On the laboratory's futureprogramme is a project tocarry out an inter -comparable exercise onthe standard humiditymeasurements of othercountries.Financed by the Depart-ment of Trade and In-dustry, NPL's work cost£25.6 million in 1983'84.The laboratory, with its staffof approximately 700, car-ries out research for theprivate and public sectorin the EEC and othercountries. Contract workearned the laboratory£3.44 million in 1984.Founded in 1900, NPL wasinitially involved primarilyin devising ways offorecasting the weather.Today, it sets Britain'snational standards, and
provides reliable measure-ments of all physicalqualities of length, mass,force, pressure, tempera-ture, time, voltage,acoustics, optical, andelectrical thermal radi-ation. All such measure-ments, from the determin-ing of screw gauges to thedesign and analysis ofwind instruments, havetheir standards set by thelaboratory, which is pri-marily concerned withhelping industry to solvetheir problems. JK:LPS
Papers invitedfor the 1986InternationalBroadcastingConventionPapers on all aspects ofbroadcast engineering,with particular emphasison emerging technology,are invited by theorganizers of the 1986 In-ternational BroadcastingConvention at Brighton
from 19 to 23 September.Satellite and cabledistribution, enhancedand high -definition tele-vision systems, and digitalmulti -channel sound areamong the subjects ex-pected to be covered.The 1986 convention andthe complementary ex-hibition will occupy boththe Brighton MetropoleConference and ExhibitionCentre -its home formany years- and also thenearby Brighton Centre.Papers should be sent tothe /BC Secretarial - In-stitution of ElectricalEngineers - Savoy PlaceLondon WC2R OBL.
Sharp Electronics has recently expanded its range ofcompact disc players with new units, such as the DX -110MD model shown in the photograph, that are attractivelypriced at £199. Sharp hopes with this move to push theCD player out of its specialist niche into the audio massmarket.
mF .,98.
electronicallycontrolled cameras
Ever smaller chips with ever larger capacitiesform an ideal partnership with the modern
camera. We thought it would interest a greatmany readers to find out how the two fit together;
and based this article on the Minolta 9000.
When Daguerre laid thefoundations of photogra-phy in 1839, he alsostarted the development ofthe photographic camera.For more than a hundredyears, the camera re-mained a purely mechan-ical device. From acumbersome square boxwith a fixed lens, it slowlyturned into a small andhandy piece of precisionengineering. that offeredmore and more facilities.It is only relatively recently
that electronics began tobe used in cameras. True,the exposure meter ofthirty, forty years ago useda selenium cell and avery sensitive moving coilmeter. For many years thistype of exposure meterwas the only photo-graphic aid that usedelectronics. Later there fol-lowed the CdS exposuremeter. and by this time ithad become smallenough to be built intothe camera. But true elec-
tronic components werethen -some twenty yearsago- still too large to befitted inside a camera.It was only when the tran-sistor became miniatur-ized and integratedcircuits (chips) made theirappearance about fifteenyears ago that cameramanufacturers began tosee the advantages ofcomplementing the con-ventional mechanicalparts in a camera withelectronic devices. And
soon electronics proved fobe not only cheaper inproduction, but alsocapable of giving moreaccurate and betterreproducible results. Re-liability remained a weakpoint for a time, but not forlong. The results weresemi -automatic cameras:electronically controlledshutters; programmableautomatics; and others.These developments gaverise to the moderncamera in which virtually
EEFebruary 1986
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1
shutter release
i, "- uO
11C3I I
integral/spotmeasurement
highlight/shadow
exposurecorrection
exposureprogamme
au to Joni slmanualrnitching
film serisitreity
timer
shutter speedsetting
aperture setting
exposure memory
central processing unit
viewfinder displaydisplay4
camera display drive4
interface autofocusprocessor
charge -coupleddevice
interface
4-
battery monitor
motor encoder
aperture encoder
aperture presetmagnet
aperture magnet
shutter magnet I
shutter magnet 11
mirror magnet
exposuremeasure-ment
4
motordrive
vienfrdsr LEDs
photodiode
snot ocus motor
86011.1
everything is controlled byelectronics. Even focusingis now accomplished withthe aid of a small motor,so that the photographercan concentrate whollyon the subject and com-position. Such a camerais, of course, an ingeniouspiece of engineering asmay be gathered from thephotograph on p. 19.
What facilities?After first looking at thefacilities of the Minolta9000, we will describe howall these are realized byelectronics. Automatic focusing
system: when the shutterrelease is half depress-ed, the subject is auto-matically put in focus. A
memory makes it poss-ible to focus first andchoose the subjectafterwards.
II Electronically controlledshutter with exposuretimes of 1f4000 to 30 s.
Exposure meter with achoice between inte-gral and spot measure-ment. With spotmeasurement it is
furthermore possible tomeasure the lightestand darkest part of thesubject separately.Again, a memory is pro-vided for storing themeasured values.
II Exposure modes:(a) manual; (b) aperturepriority auto exposure;(c) shutter priority autoexposure; (d) program-mable - in this modethe camera itself selects
the f-number and theshutter speed.
I Through -the -lens flashmeasurement, enablingthe use of all types ofexposure automatics.Red LEDs in the flashunit are activated auto-matically when the am-bient light is insufficientto allow the camera tobe focused.
Advanced peripheralequipment, such as aflash unit with zoomreflector that automati-cally sets itself to thefocal point of the lens inuse; motor drive with 5pictures per secondand autofocus priority;databack with multi -spot metering facility, in-terval timing, and a fa-cility for makingindividual exposure pro -
Fig. 1. Block schematic of atypical electronically con-trolled camera: here, theMinolta 9000. All control isvested in two micropro-cessors.
Fig 2. Construction of thephotocell. The whole areaof the cell is used for inte-gral measurements, butonly the annular part at itscentre for spotmeasurements.
grammes; and aseparate exposuremeter that can wirelessconvey the metered in-formation back to thecamera.
On top of these there aresome other noteworthyfacilities. It is, for instance,no longer possible to setthe f-number and shutterspeed manually: thewhole range of f-numbersand shutter speeds mustbe scanned with the aidof small slide switches untilthe correct values havebeen arrived at. Film sen-sitivity is set with a push-button - it can also bedone by the film itself withthe aid of the DX codeprinted on it. It takes sometime, therefore, before youare used to this camera,because the usual rotary
mechanical switches areconspicuous by theirabsence.
The centralprocessingsystemThe monitoring and con-trol of all these facilities re-quire no fewer than150 000 transistors in theshape of two micropro-cessors and some smallerICs. The block diagram inFig.1 shows what is con-trolled by the two micro-processors. The centralprocessor serves allgeneral facilities, while thesecond deals exclusivelywith the autofocus. Allother blocks within thedashed lines are separateICs. Outside the dashedlines are the operatingswitches and push -buttons;the control devices, suchas the magnetic switchesand the autofocus motor;the displays; a charge -coupled device -CCD:encoders; and the variousconnections between theelectronics and theperipheral units.The central processingunit CPU receives a greatnumber of inputs fromvarious sources.A pair of contacts in thecamera feed informationas to the sensitivity of thefilm used to an integratedcircuit that decodes andmemorizes the informationin digital form. The filmcarries a so-called DXcode for this purpose. Thememory of the IC can beread at any moment bythe CPU.Each autofocus lens con-tains a read-only memoryROM in which the prin-
cipal data of the lens arestored: smallest andlargest aperture, and focallength. These 8 -bit dataare read by the CPU thirtytimes per second. This hasbeen so arranged be-cause, when a zoom lensis used, the focal lengthchanges every time thezoom is adjusted. Slidecontacts in the lensenable the code for thefocal length to be con-
stantly matched with theactual value. In this way,the CPU is fed with up-to-date lens information atall times. In a zoom lens,the ROM also arrangesthe conversion of the slidecontact positions into aserial data stream.The CPU also needs the in-formation as to focallength for the autofocusprocessor and for thereflector position of a flashunit.The connections to themotor drive and thecamera back primarilyuse serial data streamsalso.The CPU is connected viaan interface to all partsthat switch, monitor, orsense anything in thecamera; to peripheralunits such as a flash gunor an infra -red receiver;and to the exposure meter.The exposure meter con-sists of an integrated cir-cuit that evaluates theamount of incoming lightwith the aid of a photo -
diode at the bottom of themirror compartment andconverts this analoguevalue into binary digits(=bits) that are fed to theCPU. The photodiode is avery fast type, because itnot only serves to sensethe amount of ambientlight, but alo that of flashlight. The information as toflash light is, however, usedin analogue form, becausedigitizing and processingit would take too long.Electronic flash units pro-vide flashes of between111000 and 1(50000 second.The photodiode measuresthe amount of flash lightthat falls onto the film, andas soon as this reachesthe required value, itsignals to the flash unit tostop the flash immediately.This clearly illustrates thenecessity for a very fastphotodiode.The Minolta 9000 uses avery practical method of(electrically) switching be-tween integral and spotmeasurement - see Fig. 2.
19 EEFebruary 1986
This photographshows the multitude ofelectronic devices: it isalmost unimaginable thatall this -and the manyoptical and mechanicalparts- fits into such asmall case
The photocell has thesame length -to -width ratioas the window. In integralmeasurements the totalamount of light fallingonto the cell is measured,whereas in spotmeasurements only thelight falling onto the cellthrough the annular con-ductor is taken intoaccount.The encoders connectedto the interface IC consistof tiny cog -wheels andopto-couplers. One of thecog -wheels is connectedto the autofocus motorand the other to the f-number control. In thisway, the CPU obtains infor-mation as to the angle ofrotation of the autofocusdrive motor and the f-number setting.The magnetic apertureswitches ensure that theshutter is released at theright moment.The two magnetic shutterswitches operate the firstand second section of themetal shutter respectively:
EEFebruary 1986
Fig. 3. The autofocussystem: 3a shows how thebeam of light travels fromthe object to the CCD; 3bshows how two identicalimages are projected ontothe CCD element with theaid of two lenses; thedistance between the twoimages and their locationon the CCD give an indi-cation of the state of focusof the object (3c).
20
auxiliary mirror
a=reflex mirror
b=auxiliary mirror for projectiononto charge -coupled device
c= shutter/film area
d=charge-coupled device
object
\Ilenses
len
charge -coupled
device
86011
the interval between thetwo operations is deter-mined by the CPU.The operating controls ofthe camera are shown atthe left-hand side of theblock diagram. In reality,each of these is a simplepush-button or slideswitch.The two liquid -crystaldisplays LCDs , one in theviewfinder and one at thetop of the body of thecamera, are controlled bya separate IC. Thedisplays give informationas to shutter speed, f-number, the selected ex-posure programme, themethod of measuring theexposure time, and anycorrections.The exchange of infor-mation between the CPUand the autofocus pro-cessor will be describedlater in this article.It is clear from the descrip-tion so far that the CPU isthe brain of the camerathat constantly receives,processes, and transmitsdata for the operation
and control of the variousparts of the camera. Tothis end, it contains3 Kbyte of software (maskprogrammed ROM), andsome 100 bytes of random-access memory RAM fortemporary storage of data.A noteworthy aspect is theclock frequency which, ai4.2 MHz, is higher thancustomarily found inCMOS processors.
The autofocussystemThe autofocus system con-sists of a microprocessorIC, a charge -coupleddevice CCD, and a smallbut powerful motor. Theprocessor, which has a3 Kbyte programme,receives information fromthe CCD via an interfaceand on that basis, and inconjunction with the CPU.drives the motor via aseparate driver IC.The CCD is an imagesensor containing 128
sequential image dots. Atiny part of the centre ofthe field of view is pro-jected twice via two smalllenses onto the series ofdots, as illustrated inFig. 3a. The image sensoris located at the bottom ofthe camera and obtainsits information from anauxiliary mirror that issituated behind the mainmirror and immediately infront of the shutter. Thisprocess is shown in slightlydifferent form in Fig. 3b.The double projectiononto the series of dots isshown in Fig. 3c. If the ob-ject is sharply focused,each image occupies acertain number of dots ata certain location on theCCD. All dots are continu-ously scanned by the in-terface IC, which convertsthe measured analoguevalue of incident light intobinary data. This infor-mation allows theautofocus processor todetermine the exact lo-cation of the two imageson the CCD. When the ob-
ject is not in focus, the twoimages will be furtherapart or closer together.The autofocus processorcalculates the distancebetween the two imagesand from the result it candetermine into whichdirection the lens must beturned to obtain a sharpfocus. The perfection withwhich this happens is il-lustrated by the fact thatthe drive motor is sloweddown when the object isalmost in correct focus,and shorted out immedi-ately it is in sharp focus.The motor position is thenimmediately stored in theCPU. We know from ourown experiences that thissystem works fast andreliably. The onlydrawback is that if the tinypart of the field of view isevenly coloured andlighted, this results in insuf-ficient information for theautofocus processor tofunction correctly. But insuch a situation it is quiteeasy to point the cameraat a somewhat more con-
EEFebruary 1986
Fig: 4. Another schematicrepresentation of theinterplay of the mechanicaland electronic pans in theautofocus system.
trasting part of the object,memorize this informationby half depressing theshutter release and thenpointing the camera tothe wanted part of the ob-ject again. Conversely, theautofocus system may beswitched off, and the focusset manually.An interesting featue ofthe autofocus system isthat if the ambient lighthas a value of less than 3(with 100 ISO film), somered light-emittting diodesLEDs with reflector in the
associated flash unit areswitched on by thecamera for a few seconds.These LEDs project a tinyred spot at the centre ofthe viewfinder image, i.e.from where the CCD getsits information. The spotcontains a grid that pro-vides an artificial contrast,so that the camera canbe focused in completedarkness.
ExposuremodesThe Minolta 9000 has fourexposure modes: (a)manual; (b) shutter priorityautomatic exposure; (c)aperture priority auto-matic exposure; (d) pro-grammable.When the programmable
4autofocus system
object
lens body of camera
oc>lens contacts
centralprocessing
unit
mirror
LED. in viewfinder autofocus processor
RAM
arithmeticunit
control unit
moot oarsinterims IC
driver IC
mode is selected, thecamera sets the shutterspeed and stop value, forwhich there are three dif-ferent programmes: onefor lenses with a focallength below 35 mm;another for 35 mm to105 mm lenses; and thethird for telephoto lenses.The longer the focallength of a lens, the morestress is laid by the pro-gramme on selecting thefastest possible shutterspeed to cut out telephotoblur from camera shake.The camera itself choosesthe right programmebased on the focal lengthinformation it has receivedfrom the lens ROM. Whena zoom lens is used, thecamera may even changebetween programmes, ifnecessary, when the zoomis altered.Exposure modes havealready been discussed,but there are two extrafacilities: in positions High-light) and S(hadow) thelightest and the darkestpart of the image respect-ively may be measured,after which a correction isintroduced which ensuresthat the measured partswill, indeed, be shot aswhite and black respect-ively. The correction ismatched to the contrastrange of modern filmsand amounts to +2.3 stop
at H and -2.7 stop at S.If the optional Program-mable Camera Back is fit-ted, the user can make hisown programme curves forthe exposure automatics,or to carry out multiplespot measurements, fromwhich the camera calcu-lates the average value.
ElectronicseverywhereWherever you look in thecamera you see flexiblePCBs. Miniaturization is thekey word in the cameraindustry, and the use ofsurface -mount devices isalready well established.Real switches and push-buttons are no longerfound: in the place whereyou would expect these,you will now find aminiature slide or pressdevice.These cameras are veryrobust. The electroniccomponents are allcustom made. The micro-processor ICs, the displays,the metering ICs, and theDX IC are all CMOSdevices for absoluteminimum current con-sumption. The interface ICsare made in I2L-integratedinjection logic- which iswell-known for its low cur-rent needs, high speed,
and low supply voltage re-quirement.Power is supplied by twominiature batteries, whichprovide a voltage of 3 V -sufficient for most of theICs. The 13 V supply for theCCD is obtained from aDC -to -DC converter.Although the current con-sumption of the electroniccircuits has been kept toan absolute minimum, thebatteries have to becapable of providing upto 2 A, which is the peakcurrent drawn by theautofocus motor in op-eration.The camera has a built-involtage detector thatswitches off the whole ofthe electronics when thebattery voltage dropsbelow a certain value.There is an aspect herethat needs watching. Cer-tain alkaline -manganese-Mn02- batteries,particularly Mallory andUcar, after a period of use,appear to have an in-creasing internal resist-ance when relativelyheavy currents are drawnwith the obvious result thatthe electronics areswitched off prematurely.
HB
EE 131February 1986
Mains -operated NiCd chargers are in plentiful supply, buta NiCd charger that operates from a car battery andenables fast charging is something special, The onedescribed here can charge 9; 12; or 15-yolt batteries,
DC OPERATEDBATTERY CHARGER
Lowering the e.m.f. - electromotiveforce - of a car battery is easilydone with the aid of a resistor, zenerdiode, or voltage regulator, but rais-ing it is rather more difficult. Themethod chosen here is the familiarone of voltage doubling. How this isdone in this charger is illustrated inFig. 1.
In Fig. la, switch S connects thenegative terminal of electrolytic ca-pacitor C3 to earth. so that both C3and C.: are charged to the (car bat-tery) supply voltage Ub:
Uo = UC4 = UO2 + UC3 =
UD2 + Ub-UDI =Ub (1)
In Fig. lb, switch S connects the
negative terminal of C3 to Ub, so thatthe output voltage, U0, becomes:
U0, = UC4 = Ub + UC3-UD2 =
2Ub-UO2 (2)
When the switch is returned to earthas in la, the potential across CI re-mains at Ub, because C3 cannot dis-charge. It is clear from this that U0(=Uct) will alternate between Uband 2Ub-UO2. If the switchingspeed is high enough, the outputvoltage will approach 2Ub-Uo2.
Circuit descriptionIn practice, the switching is carried
out by a Darlington pair of tran-sistors: T1 -T2 andT:-T_ in Fig. 2.
These transistors are controlled byan integrated circuit Type LM3524.Two of its features make this deviceparticularly suitable for the presentapplication: the push-pull outputstage, which can drive the switchingtransistors, and the error amplifier.The error amplifier controls thewidth of the pulses at the input of thepush-pull driver stage on the basis ofthe error signal at the output of thecharger. The larger the deviation ofthe output current from the wantedvalue, the shorter the switch -on timeof the power transistors carrying theoutput current.The voltage doubling circuit consists
of capacitors C3 and C4 and diodesDI and D2. These diodes are fastrecovery power types in a TO -220case, which is readily mounted ontoa heat sink.An oscillator in the LM3524generates a rectangular signal forthe T -type bistable and the two NORgates, and a sawtooth signal that isapplied to the non -inverting input ofa comparator. The frequency, to, ofthe oscillator is
fo =1/2nRsCI =1/295 x10-6=3400 Hz.
A reference voltage of 2.5 V is pro-vided by divider R1 -R4 and appliedto the non -inverting input of the erroramplifier. The inverting input of thisstage is provided with information asto the level of the output voltage viadivider R2 -R3.The comparator here functions as apulse -width modulator. Dependingon the level of the error signal at its
inverting input, and the level of thetriangular signal at its non -invertinginput, the comparator produces arectangular signal with varyingpulse -width at its output. This outputconstitutes the real control signal forthe power transistors. To ensuresynchronicity and a 180° phase shift,the comparator output is applied tothe bases of the drive transistors viatwo NOR gates. Pulse -width controlhas the advantage that the average
EEFebruary 1986
Fig. I. In a, bothCs and C4 arecharged to Llbminus the smalldrop across therelevant diode;in b, the outputvoltage is thesum of thevoltages acrossC3 and C4 minusthe drop acrossD2 The switch iscontrolled by anoscillator, modu-lator, andregulator.
Fig. 2. The cir-cuit of the bat-tery chargerconsists essen-tially of the con-trol, which iscontained in oneType LM3524 in-tegrated circuit,power switchingtransistors Ty toT.4 and thevoltage doublercomprising DgDz Ca and CI
2
Ub12 . . . 15 V
0
R2
0
R3
R4
LIM
RI
C2
5 16
2
9
ciLm 3524 :1::,`=
R6
C1
60
100
14/0/10n
70
R5
,11.13art LIOCII`l.
t_ILJUL
12
13
RIO
Re
T1
R11 R12
T2
UT4
DI 02
;'H!I'1" r: I .% 101
BYX 71 BYX 71
I
MJ 2955
C3
Ill -4701I40V
2N3055
IC
=20VO+ ir)
CO
vim470p
40V
86002-2
24EEFebruary 1986
Parts list
Resistors:
Fil;133;Rz:Rs =4k7
R2 = 33k
RE = 47k
=2k2R;;R,2=47 QR,3:R11=12k
Capacitors:
C1=10nC2 = In
C3;C4 =4700;40V
(axial types)
Semiconductors:
D,: D2 =13YX71
=BD140T2 = MJ2955T2=80139T4 = 2N3055
= LM3524
Miscellaneous:
2 twisted vane 10220heat sinks
2 twisted vane T0126heat sinks
2 T03 style heat sinksPCB 86002
Fig. 3. The wholeof the batterycharger, down tothe heat sinks iscontained on thisprinted circuitboard.
Fig 4. The out-put current vsoutput voltageshows that theoutput voltage re-mains substan-tially constant forload currents upto 3A.
load current remains substantiallyconstant.The current limiter - CL - in theLM3524 is not used in this appli-cation.
Construction andtestAll components, as well as the heatsinks of the switching transistors, Tito T4, and the power diodes, Di and
4
Uotv)
21
20
19
18
17
16
15
2 3 4
(A) eflOCC4
D2, are fitted on the printed circuitboard shown in Fig. 3. If the board isfitted in a case, there should be suf-ficient space above electrolyticcapacitors C3 and C4 to ensure goodventilation.Once the board has been com-pleted, the open -circuit outputvoltage should be measured. Thisshould be somewhat higher than20 V. Note that a perfect voltagedoubling, i.e. from 12 V to 24 V, is notpossible because of the saturationvoltage of power switching tran-sistors T2 and TA and the forwarddrop across the power diodes.Next, the behaviour of the circuitunder load should be checked withreference to Fig. 4. Our laboratoryprototype has an open -circuit outputvoltage of 20.2 V. Under normal loadconditions, the output voltage re-mains substantially constant (+0.5 V)until the load current exceeds 3 A.
Fast chargingDuring fast charging, the chargingcurrent must, of course, be limited inaccordance with the requirements ofthe cells or battery under charge. For
example, NiCd cells are normallycharged with a current, Ic, of 120 mAto 400 mA. If ten of these cells arecharged in series, there will be adrop, Uci, of 15 V across them. A cur-rent limiting resistor, Ra, should thenbe used, whose value is calculatedfrom
R3 = (DO-UNIC =(20-15)/0.4=12.5 [Q)
The power, Pa, dissipated in Ra iscalculated from
Pa =Ic2Ra= 0.4z X 12.5=2 [W]
Sintered -plate cells are normallyrated at 1.2 Ah, and may be fast -charged with a current of 2.5 A forthirty minutes. HS:GS
EE
February 1986
In satellite television, pro-grammes are beamed upto a satellite from wherethey are retransmitted toserve an area (called foot-print) that is impossible tocover with a terrestrialaerial. The satellites usedfor this are geostationary,that is, they orbit at thesame speed as the earth'srotational velocity. Thismakes it possible for a re-ceiving aerial (calleddish) to be firmly lockedinto position. Any dishwithin the footprint shouldreceive good -qualitysound and vision.There are several satellitesdedicated to broad-casting programmes, andthese are known as DirectBroadcast Satellites -DBS.Among these are the Rus-sian Gorizont satelliteswhich send programmesacross the world to officialSoviet ex -patriot groups.Such satellites have verypowerful transmitters, sothat only small dishes arerequired to receive theirsignals.Whilst many Europeancountries, includingFrance. Federal Germany,and the Republic ofIreland, are planning tolaunch and build DBSs,British plans to establish aDBS have been aban-doned, at least for thetime being, because ofthe enormous costs in-
volved.Until DBS gets well andtruly off the ground, pro-gramme makers, such asSky Channel and ThornEMI, have turned to com-munications satellites withspare capacity that canbe used to broadcast pro-grammes. The transmitterson board these satellites
are generally weaker thanthose employed in DBSs,but reception is just asgood with a (larger)1.8 metre dish.There are at present twoprimary satellites thattransmit programmes to
telsat V, and the other isECS-1 (European Corn-
-Ilk. -..,
- ti
o-1
l' T '-'
- - ,Alio - 4,Atio
_ -.0I,,17,4 ..-41.-
41,AkriliPseir44A.I.I.1_00. -..11, to" lit-----'"-- -
ECS Fi SPOT WEST
.._211:m..i.&....
1.,...--a-----0-0
,-
...Tv 27.5.w
\ W
---------4---
munications Satellite 1).Between them they broad-cast seventeen channels,most of them in English.Both Intelsat V and ECS-1are communications satel-lites used primarily toroute telephone callsacross Europe and to theUSA. The footprints of thesesatellites are shown inFig. 1 and 2.The NESAT system from NECBusiness Systems has beendesigned to plug into ex-isting TV sets to delivermulti -channel television toa variety of consumers.With this system, customersneed not wait to be hard-wired to a cable network;nor do they have to waitfor DBSs to be launched.The NESAT system hasseveral unique featuresthat may place the equip-ment well ahead of thecompetition in the race tobecome the number 1supplier of satellite TV re-ceiver systems designedspecifically to meet thehigh standards demandedby the British and
Fig I Coverage area("footprint') of EuropeanCommunications Satellite 1.
Fig 2. Coverage area("footprint') of Intelsat V
EE
February 19E628
Channels currently available(1) via Intelsat V:
Premiere - which shows recent box office movies forabout nine hours a day.Children's channel - with programmes aimed ex-clusively at young children and teenagers for eighthours every day.Screen sport - sports and leisure programmes for sixhours every day.Mirror Vision - movies and entertainment pro-grammes for nine hours every day.CNN -a 24 -hour news channel.
(2) via ESC -1:
Music box - pop music programmes for 18 hoursevery day.Sky channel - general entertainment for 16 hoursevery day.TV -5 - programmes from national French languagestations for 3 hours a day.New world channel -a diet of religious programmesfor 1 to 6 hours a day.WorldNet - news and information programmes fromthe US Information Agency for about 1 to 2 hoursevery day.SATI -a publishers channel broadcasting about10 hours a day.TeleClub - broadcasts mainly films for about 8 hoursa day.FilmNet ATN - mainly films and entertainment forabout 9 hours every day.World Public News (WPN) - mainly US news materialfor about 9 hours every day.3SAT - programmes from German language stationsfor about 6 hours every day.RAI - an Italian public service channel.Europa TV - (formerly Olympus TV): programmes fromEuropean Broadcasting Union -EBU- memberstations for approximately 3 hours a day.RTL-Plus - general entertainment for five hours a day.With the exception of Sky Channel, all these chan-nels are at present clear, i.e.. they require nodecoding system.
European markets.The NESAT system com-prises three main compo-nents: dish, low -noiseconverter (LNC), and in-door unit (IDU) tuner. Plan-ning permission may berequired for the erection ofthe dish in certain cir-cumstances at the present,but restrictions and regu-lations are likely to berelaxed in the near future.Many of the current regu-lations covering broadcastwere evolved some timeago, when the possibilityof utilizing near -earth or-biting satellites was un-dreamt of.The low -noise converterhas a low -noise amplifier
that uses gallium -arsenide(GaAs) field-effect tran-sistors which reduce noiseand thus increase picturequality.The IDU tuner enables theuser to preset differentparameters adopted inthe ECS-1 and Intelsat Vsatellites for each chan-nel. Selecting channels isfrom then on simply amatter of pressing the ap-propriate button on thefront of the tuner. The tuneris designed for use withany type of television re-ceiver.The unique feature of theNESAT system is the facilityfor simultaneous receptionof differently polarized
signals. Channel operatorsuse either X or Y polariz-ation. NESAT is the onlysystem capable of receiv-ing signals with both typesof polarization and pass-ing them on to the TV setvia one cable.NEC Business Systems(Europe) Limited is theBritish subsidiary of theNEC Corporation. which isthe recognized industryleader in a variety of hightechnology electronicssectors. It is one of theleading and one of thelargest electronicsmanufacturers in theworld, with 70 plantsthroughout the world. andmore than 74 000 people
Fig. 3. NEC:s 18 m dishwith two low -noiseconverters, which arestacked to enable simul-taneous reception ofhorizontally (X) andvertically (Y) polarizedsignals.
Fig 4. Close-up of twostacked low -noiseconverters, mounted ontothe dish as shown in Fig. 3
Fig. 5. NEC IDU (indoorunit) tuner. designed to sitbelow or above the TV set,is slimmer than most videorecorders.
making and marketingproducts that are sold in140 different countries.NEC's experience in hightechnology spacerelated telecommuni-cations systems goes backsome 15 years. Around theworld, there are no fewerthan 6000 NEC -equippedmicrowave stations, whilesatellite communicationsearth stations (recog-nizable by their large dishaerials and which havebecome a symbol of the20th century) manufac-tured and supplied byNEC account for almost 50per cent of the world'stotal installations. NEC arealso involved direct inmanufacturing equipmentfor use in televisiontransmitters, and thecompany has had some15 years' experience intransponder design. Itrecently won a contract tosupply transponders foruse in all the Intelsat VIseries of communicationssatellites. Transponders arethe devices on boardsatellites that receivesignals from earth stationsand relay them back toreceiving systems.Satellite TV AntennaSystems claims to haveachieved a breakthroughin satellite TV reception bycutting the cost of receiv-ing equipment by half,largely through technicaldevelopment, and expectsthat private ownership ofsuch equipment willconsequently be en-larged.'The company, known asSATVRN, is offering com-plete systems that retail atstarting prices of less than£1000.The systems have threeelements: the dish aerial,which receives signalsfrom the satellite; the elec-tronics head unit,mounted on the dish,which amplifies thesignals and converts themfor TV reception; and thetuner, which is pluggedinto the TV set.Dishes 1.2 metres acrosssupplied by SATVRN canbe mounted in the gardenof a small home, on anoutside wall, or on theroof.
The firm also offers satellitemaster aerial TV (SMATV)systems, which are com-mercial installationssuitable for hotels, housingestates, and apartmentblocks. Hotels using thesesystems can offer TV pro-grammes from their owncountries to foreign guests,for instance.SATVRN has suppliedequipment to the US Navy,the European SpaceAgency, and customers inwestern Europe,Yugoslavia, Israel, the GulfStates, and Canada.Another breakthrough insatellite TV receivingequipment occurred inthe home of electronicsengineer Mr Steve Webb ofSwinton, near Malton,N. Yorks. His three childreninduced him to design a
simple means of receivinginformation being broad-cast by spacecraft. Ac-cording to Mr Webb,"games are useful to helpyoungsters get interestedin computers, but they canbecome a total misuse ofthe technology. Mychildren got fed up play-ing space invaders, so weset about trying to com-municate with two Britishsatellites to get informationand pictures".Using the know-how hehad acquired in 10 years'work on satellite systemswith two major UK spacecompanies, he worked forfifteen months to producea receiving system thatconverts satellite signalsand decodes them via acomputer onto a TVscreen.
29 EE
February 1986
"The first receiver I built for_the children was crude,"said Mr Webb. "So, I de-cided to develop a fullyautomatic model for any-one to use." The result is afully automatic versioncalled ASTRID, acronym forAutomatic Satellite Tele-metry Receiver and Infor-mation Decoder. The totalcost of ASTRID and ac-cessories is £149.One of the biggestassociations of computerusers has described thedevice as an "outstandingproduct and a majorbreakthrough, bringingmany exciting oppor-tunities to amateur scien-tists and radio amateurs':Mr Webb believes thedevice will particularlyappeal to schools in awhole range of relatedsubjects ranging fromgeography and maths toscience and computerand radio technology. Theresearch and develop-ment work was funded bythe Micro MetalsmithsMicrowave Company ofKirkbymoorside, N. Yorks,which Mr Webb joined lastyear.ASTRID is reported to beattracting worldwide in-terest following tests byscience teachers through-out Britain, associations ofcomputer users, and tradepublications.NEC Business Systems(Europe) Limited35 Oval RoadLondon N14/1 7EATelephone: (01) 267 7000Telex.- 265151Fax: (Of) 267 1645/1619
Satellite TV AntennaSystems Limited10 Market SquareStainesMiddlesex TW18 4421./Telephone: (0784)61234 '52155Telex: 877440
Fig. 6. NEC manufacturesand installs almost 50 percent of the world's satellitecommunications earthstations, such as the oneshown here.
Fig. 7 Typical transponderas supplied by NEC foruse in the Intelsat series ofsatellites.
EEFebruary 1986
30
.
11111111" ACTIVE AERIALWITH SMDS
Now thatsurface -mount
devices -SMDs -are becoming available,
many readers will, nodoubt, want to gain practical experience
with these new components. What better way to startthan with this tiny active aerial?
As stated in Surface -mountTechnology (Elektor Elec-tronics December 1985),all major semiconductormanufacturers are heavilyengaged in the develop-ment and production ofsurface -mount compo-nents. These componentsare much smaller thanconventional ones andhave no or very short con-necting terminals, sincethey are intended to besoldered direct to the cop-per tracks of a circuitboard. In general, theseboards no longer haveholes drilled in them,other than for fixingpurposes.It should be noted that,although all majormanufacturers have agood range of SMDs inproduction, these devicesmay not yet be availablefrom all distributors andstockists.
CircuitdescriptionThe active aerialpresented here is a verysimple circuit, which is pri-marily intended as apractical introduction to
working with surface -mount devices. It hasbeen designed as anadd-on unit for a caraerial and for portablereceivers where a 12 Vsupply is available. Theaerials used with thesereceivers usually have afairly high resistance,whereas the receiver inputimpedance is typically ofthe order of 50 to100 ohms. The resultingmismatch has a detrimen-tal effect on the noise fig-ure of the receiver.
The present circuit pro-vides a large degree ofcorrect impedancematching via a dual -gateMOSFET, T1. The aerialsignal is applied to gate 1of the device, while thepotential at gate 2 is ar-ranged at half the supplyvoltage, i.e., 4.5 to 6 volts.The MOSFET amplifier iscoupled to the receiver in-put via a short length ofscreened 75 -ohm cable(as normally used in carradios). The conductor inthis cable also serves toconnect the supplyvoltage to Ti. The chokespresent a high im-pedance to frequencies inthe receiver range, so that
they cannot enter the re-ceiver via the supply line.The 560 pF capacitorisolates the receiver inputcircuits from the DCsupply.Note that the MOSFET hasa typical mutual conduc-tance of 20 mS, so that itperforms best with outputimpedances greater than50 ohms. As the medium -and long -wave input cir-cuits of car radios are nor-mally high impedance,the present circuit willwork well on those wave-band& FM receiver inputsare generally low -impedance, so that thecircuit will not be so effec-tive on the VHF bands
ConstructionNote that the circuit boardis not available readymade through ourReaders Services. It is bestmade from the pattern onpage 44 or from a pieceof prototyping board.Soldering should be car-ried out with an iron ratedat no more than 18 wattsand fitted with a sub-miniature tip to preventdamage to the fragilesurface -mount devices. The
tip may be made from alength of SWG20 (1 mmdia) bare copper wirewound around theheating element of theiron. Useful tips on mount-ing the devices are givenin Surface -mountTechnology in theDecember 1985 issue ofElektor ElectronicsThe component layout isshown in Fig. 2. In portableradios it is advisable tosolder the aerial termi-nation direct to Ct Note,however, that the presentcircuit can only be used ifthe portable radio has aseparate aerial input thatbypasses the built-in ferriteaerial.
FinallySince it is impossible toachieve absolutely correctimpedance matching, thecable between the pres-ent circuit and the re-ceiver may radiate. If theresulting signal is pickedup by the aerial, theMOSFET stage mayoscillate. All this can beprevented by winding theinitial length of the con-necting cable around aferrite toroid or rod asshown in Fig. 3. JB:BL
111 EE
February 1986
Fig. I Circuit diagram ofthe proposed active aerialin which all electrical com-ponents - except thechokes - are surface -
mount devices.
Fig 2. Circuit boardshowing a possible layoutof the active aerial circuit.This board is nor availableready made, but may bemade from a piece ofprototyping board. Its di-mensions are about250 x 250 mm.
Fig 3. Any tendency of theconnecting coaxial cable toradiate may be suppressedby winding its initial lengtharound a ferrite rod ortoroid.
The aerial resistance isthe ratio of the powersupplied to it and themean square value ofthe current at its feedpoint. This resistancetakes into account theenergy consumed bythe aerial system as aresult of radiation andother losses.
The noise factor, F, of areceiver is the ratio ofthe input power, Po,and the noise outputpower, No: F=Po!No.The noise figure is oftenexpressed in decibels:Fcia=10logioF.
Mutual conductance,gm, is the ratio of achange in output currentto the causative changein input voltage when theoutput voltage is held con-stant. It is expressed insiemens -S- which hasreplaced, and is equiva-lent to, the mho (recipro-cal of ohm)
Cl G2
BF990
US
EE 113February 1986
Cartridge board withuser -programmable
EPROM
EXTENSIONS -2Second in the series on home-madeMSX add-on units, this article presentsa cartridge extension board and fulldetails on EPROM -stored programs.
As evidenced by the first part in thisseries (Elektor Electronics January1986), the cartridge slot available onMSX type computers may be used toeffect connection of home-made ex-tensions like the Elektor universalI/O bus.Usually, commercially available car-tridges merely contain an (E)PROMto run a program (game, utility). It is,therefore. possible to construct adevice that will hold user -pro-grammed EPROMs whilst retainingthe possibility to insert existing car-tridges. Our design offers the follow-ing facilities.
1. Easy connection of furtherhardware -extensions, like the
Elektor universal I/O bus.
2. The present board may be con-nected to the existing 50 -way out-
put port of such MSX computers asthe Spectravideo type.
3. The board may be used as anangled cartridge adapter or a ver-
satile IC socket to hold several typesof user -programmable EPROMs with2, 4, 8, 16, or 32 Kbytes capacity.
4. The board is useful for the connec-tion of a Yamaha synthesizer.
The MSXcartridgeAs shown above, the present car-tridge extension board is the sort ofdesign that many users would un-doubtedly like to see: universal, ac-cessible for measurements andexperiments and with the possibilityto insert one's own EPROMs. How-ever, before this can all come true,some knowledge is required of the'cartridge conventions' used in MSXBASIC. We shall, therefore, firstexamine a typical MSX start-up pro-cedure.After power -on, MSX BASIC alwaysestablishes the amount of RAM (Ran-dom Access Memory) between ad-dresses 8000 and FFFF, and activatesthe largest continuous area en-countered. Next, BASIC examinesslot address range 4000...BFFF.Each slot occupies 16 Kbytes, div-ided in four pages. At the beginningof every page. a sequence of codesis read to identify the slot contents.The bytes which supply this infor-mation are located in a fixed order,as shown in Fig. 1. The function ofeach code is as follows:ID (identification): a two -byte codethat indicates the presence of a car-tridge (E)PROM. In that case, BASICreads 41hex and 42hex (ASCII A andB). respectively at these locations.INIT (initialization): a vector (addresspointer) for the initialization routineassociated with the cartridge func-
EE
February 1986
tion. In case this is not required, adefault value 0000 is present at theselocations.STATEMENT: a vector pointing tothe cartridge statement -handler, ifapplicable. If not, a default 0000 ispresent. For further details on thisvector, refer to the user manual sup-plied with the computer or the car-tridge.DEVICE: a vector pointing to thecartridge device -handler, if ap-plicable. If not, a default 0009 is pres-ent. Refer to computer manual forfurther details.TEXT: a vector pointing at the token -coded BASIC program text in thecartridge. This pointer is of great in-terest to users who want to put theirown BASIC programs into EPROMs.All foregoing addresses are stored inthe cartridge (E)PROM with theirleast significant byte (LSB) first, as iscustomary in Z80 machine languageprogramming.
Practical circuitActually, the present design, asshown in Fig. 2, is not much of a cir-
cuit at all; it is rather a truly universaland user-friendly IC socket for the27XX series of EPROMs, rangingfrom the well-known Type 2716(2 Kbytes) to the giant Type 27256(32 Kbytes). Note that EPROMmanufacturers have generallyagreed on using the last two or threedigits of the type indication to statethe memory capacity in kilobits. Div-ided by eight, this will give thenumber of programmable bytes (onebyte equals eight bits).To accommodate every member ofthe 27XX family, the present exten-sion board has a number of jumpers,which will have to be installed orremoved as follows:jumper A selects between Types27128 and 27256 EPROMs and shouldbe installed with the latter type in-serted.jumper B connects terminal 27 of aType 27128 to +5V. Thus: jumper Afor a 27256, jumper B for a 27128.jumper C connects Vcc terminal 24of 24 -pin Types 2716 and 2732 to + 5V.
jumper D connects address line A13to terminal 26 of 28 -pin Types 27128and 27256. For the 2764, jumper C
must be installed (pin 26 to +5V, notboth jumpers C and D).jumper E connects terminal 23(28 -pin types) or terminal 21 (2732) toAll and must be installed for allEPROMs except Type 2716.jumper F connects Vpp terminal 21of a Type 2716 EPROM to +5V.jumpers G, H, and I connect theEPROM CE terminal (chip enable) toMSX signal CS1, CS2 or CS12 in thatorder, CSI being the ROM selectsignal valid for address range4000. . JEFF, CS2 for 8000. . BFFF,and CS12 for both ranges, i.e.
4000... BFFF. Up to and including aType 27128 EPROM. either CSI orCS2 is used; a Type 27256 requiresthe CM signal. Table 1 summarizesall available jumper configurations inorder that any user can readily findand set the jumper combination asrequired for the EPROM in use.So far, only EPROMs have been men-tioned because these are mostreadily available and programmable.However, it will be evident that pin -compatible proprietary PROMs orROMs will work just as well.If fitted in the MSX computer, the in -
2co00rast1 cs1. sc'An L.Gt
K1 K2 50149)
2 Ill
50 490 000
00
/ o0
o 02 I
K3
0000000 0 /146
000
0
0
00
44 SW'
00o21
3
-oCo4-08
2 '2
XJW
2
0A D0 0
0 2' t;
0 a a
A
EbH
C2 C31=I=In
T901MM
479'CV
tin ftrRe F. tocsctto 50 ttel
IC127
xxx001..00 e:::9rz /* 0 .1..0 Cs^.00
Cl
Vi/1.11c 1E00 02 2
R.. v. A.' ft X. 0 0: .7
4709
Fla. I Thesecodes at thebeginning ofevery slotaddress -blockform a software'pisiting card' ofthe cartridge, foridentification byMSX BASIC.
Fia. 2 Practicalcircuit of thecartridgeextension board.The jumpers areset to suit thetype of EPROMused(2...32 Kbyte).
Fig. 3 Pindesignations ofthe popular27XX series ofEPROMs,arranged inorder of memorycapacity.
3
A7
AS
As 3
AL
A3 5A2
A2
at r0:02 11:
12
2716
2K x8
124 Vec123 Al122 1921 Vry.
20 OE
19 Al 016 CE
17 D7-£116 D6
113 DS214 043,3 03
2732 (A)
A7 1C
AG 2AS 3
A4 4A3 5AZ 6Al 7
AO 8DO 9DI 10.D2 11C
IOC
2764
7'2' VC° :le; 21 CC :23 ASA3 3C
,,1.2221
A3
dAll A6 4C
4K x8
'120 ITE/Vpp AS 5.19 A10 A4 fit,
;01 CE A] 7
17 127 4.2
115 06 Al 9
115 DS A0 IOC'
214 DO II(D4DI 12C313 133
02 13Ctar:
27128 27256
328 vee vn. ( L. 72 vce vn lc327 POI Al2 2( 327 PM .412 2C
326 NC A7 3C 325 AI3 A7 3C
325 Al AS 4C 325 All 6.6 4524 AS AS Sr- )24 Al AS S.
323 All A4 6C 23 All AA 6C322 OE A3 7C1- D22 R Al 7C
321 A10 42 81 )21 A10 A2 8C.
320 CS Al 9C9 07 AO io
; 320 a Al 9
DO lic17 DS DI I16 04IS 03
IS D6n,6 ur 315 03
n 3t7 OS-
02 13C
316 06
3* 04
IN D7 AO 10
DO 'ICDI 12C
..i. I4CDI 13C
8K x8 16K x 8
325 Vcc327 Alt326 A13325 AS
42. AS123 All122 in)21 AtO32* CE
13 D7
'315 D6317 DS316 DI)15 D3
85130332K x 8
EE
February 1986
Listing 1 Thismemory dumpprogram may beused to analyselarger BASICprograms asthey reside inRAM; it provideshexadecimalpresentation ofany givenmemory areaand may be putin EPROM tofunction as astand-by utilitycartridae.
Parts list
34
Capacitors: Ci = 470pC2 = 100n
C3 = 47y;10V
Semiconductors:
ICI =2716,2ra:2764:27128;27256 or corre-sponding pin -compat-ible IP1ROMs.
Miscellaneous:
K2 = 50.way (2 x 25)
male PCB connectorKa = 50 -way (2 x 251
MSX female slot con-nector. 0.1 inch pitch
18 -way 12 x 91 male
locking plug assemblyfor female jumpers
(e.g. Minicon Latch PI18w).
4 jumpers
PCB 85130
(65.5 x 98mm)
Flo 4 Thisthrough -platedPCB is small buteffective when itcomes toplugging inexistingcartridges,hardwareextensions, orEPROMS. holdinguser proorams.
Listing 1.
DUMP
10 CLS
20 INPUT"start";A30 INPUT"end";B40 FOR C = A TO B50 LPRINTUSIN6"\60 FOR D=0 TO 1570 LPRINTUSIN6"\VBO NEXT90 C=C+15:LPRINT"100 NEXT110 END
\";HEXVC);:LPRINT" ";
';HEMPEEK(C+D));:LPRINT" ";
":LPRINT" "
sect/remove protection circuitry willdetect the connection between SW1and SW2 as present on the extensionboard.Three connectors are provided onthe board; K1 is simply the edge ofthe extension board with connectingcopper tracks on both sides for in-sertion in the computer cartridgeslot; PCB connector K2 is a standardmale 50 -way type (2 rows of 25 pins);while K3 is a cartridge slot connectorwith 0.1 inch pitch contacts. just asthe one inside the computer.
ConstructionTrack layout and component mount-ing plan of the cartridge extensionboard are shown in Fig. 4. The ready-made PCB is a moderately sized,through -plated type, available asusual through our Readers Services.The soldering islands and slot con-necting tracks have been pre -tinnedto guarantee stable contacts. Use of a28 -way ZIF (zero insertion force)socket is highly recommendedbecause sooner or later EPROMswill have to be taken out, erased witha UV source. programmed again,debugged. etc., and this perhapsseveral times. The cheaper types ofIC socket will inevitably developbad terminal contacts after pro-longed use...
ApplicationsNow that a neat, universal (E)PROMsocket is available, frequently usedprograms may be stored in adedicated EPROM, just as with com-mercially available cartridges, but agood deal cheaper. However, beforeuser programs may be successfullystored in EPROM, the MSX BASICprogram storage method needs tobe unravelled.Note that the following descriptiondoes not apply to machine -codedcartridge programs, since these re-quire a more elaborate vectorsystem. For a BASIC program, then,the ID and TEXT vectors are essen-tial; they are located at XX0i3-)0C01and XX08-XX09 respectively (seeFig. 1). Because the first 16 bytes ofthe cartridge (E)PROM are reservedfor program identification andsystem vectors, the token -codedBASIC program itself may be storedfrom location XXIO onwards.MSX BASIC programs are aenerallystored in memory from address 8000onwards, so the value 80 may be readfor XX from now on.At 801a the CPU must invariably readbyte 00. The next locations contain aso-called link address (two bytes)and a line number (also two bytes);
next comes a token -coded line ofBASIC text, terminated with a byte 00.This procedure is repeated for thefollowing text lines.To find out the hexadecimal codesthat constitute a program, it isnecessary to run the DUMP programof Listing 1, preferably with a printerconnected to the computer. In case aprinter is not readily available, thebytes may be put on the screen bychanging all LPRINT commands intoPRINT and next changing value 15into 7 in lines 60 and 90 to allow forthe reduced number of printablecharacters per line. Note that theDUMP program may be 'attached' toany user program in memory byentering it from, say, line 10000onwards.After RUN 10000, the programprompts for a start and end -of -program address; the former isalways &H8000, the latter depends onthe actual size of the program, which
A B C D E F G H I
27256 10--0 0-0 0-3 0-0
27128 0-0 0-0 0-0 0-0 *0-*
2764 0-0 0-0 0-0 0-0 0-* 0
2732 0-0 0-0 *0-0 0-* 0
2716 0-0 0-0 0-.0 1:3*0
55130-T1
= jumper= select either H or I (see text)
Table 2.
0 1 2 3 4 5 6 7 8 9 A B C D E F
8000 0 7 80 A 0 9F 0 16 80 14 0 85 22 87 74 61
18007 *10 Tk EOL - 18016 '20 Tk s t a
8010 72 74 22 36 41 0 23 80 1E 0 85 22 65 6E 64 22r t ; A EOL 18023 *30 Tk
8020 36 42 0 33 80 = 28 0 82 20 43 20 EF 20 41 20 D9B EOL 18033 Tk sp C sp Tk sp A sp Tk
8030 20 42 0 4E . 80 32 0 9D E4 22 F 20 20 5C 22 3Bsp B EOL L804E *50 T1( TIt sp sp
8040 FF 9B 28 43 29 3B 3A 9D 22 20 20 22 36 0 50 80Tk Tk ( C ) : : Tk " sp sp EOL 18050
8050 3C 0 82 20 44 EF 11 20 D9 20 F F 0 78 80 46'60 Tk sp D Tk 0 sp Tk sp Tk 15 EOL 1.8713
8060 0 9D E4 22 5C 22 3B FF 9B 28 FF 97 28 43 Fl70 Tk Tk ; Tk Tk 1 Tk Tk ( C Tk
8070 44 29 29 3B 3A '9D 22 20 22 3B 0 81 1 80 50 0 83D 1 ) : Tk sp ; EOL L8081 '80 Tk
8080 0 96 80 5A 0 43 EF 43 F1 F F 3A 9D 22 20 22Tk 15 Tk
8090 3A:
9DTk
22"
20sp
22"
0
EOL9C 80
1809C64 0 83
'100 Tk0
EOLA2 80
Le.3A26E 0
*110
80A0 81
Tk0
EOL0 0 8 41
A0 C5 32 76 80 0 0 0 0 8
-------__
SOBO 42B
0 C5 32 51 20 0 0 0 0 8 43C
0 C5 32 59
8000 60 0 0 0 0 8 44D
0 41 90 0 0 0 0 0 0
8000 3A 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
80E0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
80F0 0 0 0 0 0 0 0 0 0 I 0 J 0
f
0 0 0 0 0
8100 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
: line number finI : Link address llhh
Tk : Token bytesp : space
EOL : end of BASIC line: end of program
111 EE
February 1986
Table 1Summary of thenecessaryjumperconflourations forevery type ofEPROM in the27XX series. TheChoice betweenjumpers H and Idepends on theselected memoryarea (see text).
Table 2 Thistable is a hexa-decimal dump ofthe DUMPprogram as itresides in MSXcomputer RAMmemory. Allbytes have beenanalysed. and itmay be useful toreconstructprogramListing 1 from it!
EEFebruary 1986
Table 3 Thesedata are burnedinto an EPROMto function as autility cartridgecalled DUMPCompare theshadedaddresses withthose in Table 2to note the moveup by 10bev andthe correspond-ingly adaptedLSBs.
36
Fig. 5 TheSpectravideoMSX computermay be connec-ted to thecartridgeextension boardwith a shortlength of 50 -wayribbon cable andtwo suitablesockets.
Table 3.
0 1 2 3 4 5 6 7 8 9 A B C D E F8000 41 42 0 0 0 0 0 0 10 80 0 0 0 0 0 08010 0 17 80 A 0 9F 0 26 80 14 0 85 22 73 74 618020 72 74 22 36 41 0 33 80 1E 0 85 22 65 6E 64 228030 3B 42 0 43 80 28 0 82 20 43 20 EF 20 41 20 D98040 20 42 0 SE 80 32 0 9D E4 22 5C 20 20 5C 22 3B8050 FF 96 28 43 29 38 3A 9D 22 20 20 22 3B 0 6D 808060 3C 0 82 20 44 EF 11 20 D9 20 F F 0 88 80 468070 0 9D E4 22 5C 5C 22 3B FF 98 28 FF 97 28 43 Fl8080 44 29 29 3B 3A 9D 22 20 22 3B 0 91 80 50 0 838090 0 AS 80 5A 0 43 EF 43 F1 F F 3A 9D 22 20 2280A0 3A 9D 22 20 22 0 AC 80 64 0 83 0 82 80 6E 08080 81 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
is lengthened by some 160 bytesbecause of the addition of DUMP.After this first aquaintance with thehexadecimal dumping format anduse of DUMP in practice, the com-puter memory may be cleared(NEW) and DUMP entered as shownin Listing 1, i.e. from line 10 onwards.Run DUMP, enter &H8000 as the startaddress and &H8100 as the end, andhave a look at the machine code thatconstitutes this little program. Withthe use of Table 2, try to retrace thefamiliar BASIC lines to understandthe MSX memory storage principle.Note that the link addresses and linenumbers are in reverse order, that iswith their LSBs first. All standardBASIC commands have a corre-sponding token -byte, and it will notbe difficult to spot some of them:
82h= FOR; 9Dh=LPRINT; EFh="="(equal sign); 83h = NEXT; Flh="÷";E4h = USING; etc.
If this is all sufficiently clear, we willnow consider the EPROM data.
EPROM dataIt will be evident that the computerdoes not consider the machine codecurrently present in locations 8000and up as located in a cartridge,because the identification group ofbytes as already discussed is notpresent at the beginning of theprogram (8000...800F). To obtain fac-tual EPROM data, the whole machinecode program will have to be movedup by sixteen (10h) bytes, the linkaddresses changed accordingly, andthe identifiers placed at the begin-ning as outlined above.A practical example of how this maybe accomplished is shown inTable 3; this is the DUMP programagain, but this time as present in anEPROM; compare the data withthose of Table 2 to gain an insightinto cartridge EPROM operationwith MSX BASIC; program anEPROM with these data, plug it intothe cartridge ZIF socket, and runyour own utility cartridge.Finally, a word about lengthier, more
complicated BASIC programs andtheir storage in EPROM. As alreadysuggested, the DUMP program maybe attached to them at a suitable highline number, e.g. 10000. With themain program fully debugged andoperational, run DUMP, spot the linkaddresses, add 10her to them, movethe program up by 101-hex addresses,and write a suitable sequence ofidentification bytes. The linkaddresses always point to the nextone, and are thus easily picked outfor modification. Program end ismarked by a link address reading0000. but the real end, that is withoutthe added DUMP program, may befound by looking for the hexadeci-mal equivalent of 10000, bytes 1027 inthat order; next, change thepreceding link address into 0000.Finally. note that programs run fromcartridge may, of course, not beedited because they reside in read-only memory.
SpectravideoconnectionThe extension board need notalways be inserted into the com-puter's cartridge slot; the Spec-travideo MSX computer, for instance,features a 'real' 50 -way expansionconnector for receiving anappropriate flat ribbon type socket.The present extension board is thenconnected with a short length of50 -way flat ribbon cable with such asocket on either end of it, as shownin Fig. 5. Note that there is a slightoddity with the Spectravideo outputexpansion connector; the tiny arrowon it does not indicate pin 1 as usualpractice, but pin 50. However, noproblems should be encountered ifthe example given by Fig. 5 isfollowed.This finishes the present article onMSX extensions; a further instalmentwill deal with the construction of abus -board for this type of computer.
GD:BL
EE
CORRECTIONSAn IBMcompatible micro(June 1985-p.6-33)The frequencies in the firstcolumn should read18.432 MHz and 15.750 MHzand not 18 432 MHz and15 750 MHz.
Infocard 115(October 1985)The formula for the kinetic
energy of moving air shouldread: P= 7-Z eAv3, i.e. the third
power, not the square, of thewind force.
Car radioamplifierNovember 1985-p.46)The working voltage ofcapacitors Ci...;C,....;andC5... should read 16 V and not6 V.
Variable filterfor DX(January 1986-p.60)Photographs 1 and 2 on page65 were inadvertently inter-changed at the printers.
EEFebruary 1986
40
MAKE YOUR OWN PCBSHow to make your own PCBs
You require an aerosol of 1SC/draft'transparentizer (distributors for theUK:Cannon & Wrin, 68 High St..Chislehurst, Kent. 01 467 0935, whowill supply the name and addressof your local stockist on request), amercury vapour lamp, sodiumhydroxide (caustic soda), ferricchloride, positive photo -sensitiveboard material (which can be ei-ther bought or home made by ap-plying a film of photo -copyinglacquer to normal board material). Wet the photo -sensitive (track)
side of the board thoroughlywith the transparent spray.II Lay the layout cut from the
relevant page of this magazinewith its printed side onto the wetboard. Remove any air bubbles bycarefully 'ironing' the cut-out withsome tissue paper. The whole can now be exposed
to ultraviolet light. The exposure time is dependent
upon the ultra -violet lamp used,the distance of the lamp from theboard, and the photo -sensitive bo-ard. If you use a 300 watt UVlamp at a distance of about 40 cmfrom the board and a sheet of
86002 Battery -operated NiCd charger
8ICC3 RF bOLIf
perspex, an exposure time of4...8 minutes should normally besufficient. After exposure, remove the lay-
out sheet (which can be usedagain), and rinse the boardthoroughly under running water.III After the photo -sensitive film
has been developed in asodium hydroxide solution (about 9grammes of caustic soda to one li-tre of water) for no more than21/2._ .3 mins at 20°C. the boardcan be etched in ferric chloride(500 grammes of FeCI3 to one litreof water). Then rinse the board(and your hands!) thoroughly under
running water. It is advisable towear rubber or plastic gloveswhen working with caustic soda orferric chloride solutions.III Remove the photo -sensitive film
brom the copper tracks with wi-re wool and drill the holes_
DANGER! Ultra -violet light isharmful to your eyes, so whenworking with a mercury vapourlamp. wear some form of effec-tive eye protection.
86005-1 Car burglar afa rn
Qt7 Ts( (N\*Y:-\-?*-1
f0to
O 0 0 El 0 0 0 El 0 0 0CI El El CI El El El El El Et El ElCI El El CI El El El El El El El ElO 0000000000
LEI 0 0 El 0 0 0 El 0 0 0
00
86005 Car burglar alarm
41 EEFebruary 1986
Books from Elektor ElectronicsBEGINNERS' BOOKS
RESI & TRANSI1,,,e, o' 511ip iaitaars 1.,a,A feint in
...men two enterprising characters exploreric4r1 of electronics in thee own inimitable
Their adventurer are tun of tension.ii,:t-aauSe they Often go against the currentwhereby they encounter much resisianeebefore they reach thee goat. These bootsfamtiarde the reader with electronics an anarmorial way exciting, playful. yet thorough.Pan 1 comes complete with a printed circueboard and reserieterPut Ielairsh the Mysteries of Elie -ones £6.10Part II-
olt £4.80
DIG/BOOKProvides a simple step-by-step introductionto the basic theory and application of digitalelectroni and gives clear explartations ofMe fundamentals of digital circuitry, backedup by experiments d=esigned to reinforce thisneoly acquired knowledge. Suppled with aneperniventer's PCB
Price: 16.30
STARTING ELECTRONICS,VOL. 1
t,,tn s technological socen most of hiere electronic equipment at same terse_Radio and television, hi fi and tape recorders.digital clocks and watches. electronic con-trollers for washing machines and centrali.eatioo systems. electronic ignition systemseir cars. and calculators and computers areoast a few of the examples of how eiecuonii_affects our lives_Starting electronics is written foe those...be want to gain an understandnq of theprinciples underlying such equipment_ Howir.sn. the book is not crammed lull of dryth eory. but aims to demonstrate the practi-cal aspects of electronics through numerouseiperimental circuits that Can be bull easilyard quickly_Volume 1 assumes no previous knowledge ofeleetionics- the reader is takers step by stepinto the wide and wonderful world of elec.-7,0MCS and on the journey he is acquainted..its a manlier of basic circuits. These or -Mrs will always be around because they are
so basic and may, therefore be found inmost electronic equipment.
Price 14.70
MUSIC & GAMES
FORMANTcenstructional detaes of the
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Price: E6.30
EXTENDED PRESET UNITFOR THE POLYPHONICSYNTHESIZER
:., culmination of a prozectwmcn ...as started in the October 1981 mate Bektor and to which since then no fewerthan nine articles have been &skated ft isno exaggeration to say that the polyphonicsynthesizer can be used to its full potentialmay with the extended preset unit. TheCookie a &wicked into fare distinct sections:the construction arid fitting of the variouscards. a functional description. calibrationand testing. fault-finding. and tracking of theecitage-controaed filer and low -frequency
JUNIOR COMPUTER BOOK 2Follows m a logical continuation of Book 1.and contains a detailed appraisal of the soft-ware Three major programming toots, themonitor, an assembler and an editor, arediscussed together with practice/ proposalsfor input and peripherals_
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JUN/OR COMPUTER BOOK 3The nest. transforming the basic. single -board Junior Computer into a complete pereorsal computer system.
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JUNIOR COMPUTER BOOK 4Book 4. the Last in the series, describes ailthe software required to operate the com-plete system. A number of peripheraldevices. such as a printer and a video ter-minal. may be 'hooked up' to the computer.During the final stage m its 'growth.. themachine is able to extend its linguistic skins.for a special version of Basic rs nowayagable on cassette
Price: f6.90
JUNIOR COMPUTER VIA 6522This book deals with the wolenownsetae Interface Adapter IVIAI type 6522.Although it is an indispensable addition tothe four boots already devoted to the JuniorComputer. it es not airnee solely at Juniorusers. but at anybody v.Ild hag a system withone or more 6522s. It affords a completefamiliarization with the flexible and effectivecompeoent.
Price: £3.50
JUNIOR PAPERWARE 1t.t.,1.1,at,z.r.s 'at Ole Fe l F..tE EPROM:Sulitee lusting, Hex thump of the Softwarecruncher and puncher [Eel.- tor 85. May
Price: £2.10
JUNIOR PAPERWARE 2Source listing of the bootstrap loaderOhio Scientific Floppys. Hex dump of theEPRO7.1 lESS 515!.
Price 12.10
PAPERWARE 3 & 4The ILIsdoate for a Unewesal Temenal hasalready been described in Elektor It consistsbasically of a VDU card and a CPU card. but.of course, to make the terminal work somesoftware is a.5.: TwO new books arenow ayaiatO - :ns need. Paperware
ware. but also , -, and'outs of the tern. or -; providesat the software and etre: inlormaton forusing the Universal Terminal with the JuniorComputer either in expanded form or withDOS.
Price: Paperware 3 E2.70Paperware 4 fzez
MICROPROCESSORHARDWAREThu. book describes a range of peripheralequipment that can be corinkted and usedwith an assortment of personal computerswhich use the 6502, 6203. Z80 or the 8030CPU
Price: 0.913
300 SERIES
300 CIRCUITSFor the home constructor - 300 projectsranging from the basic to the very ereMi.-heeled
Price. 15.80
oscillator- Its posstee. to build and test a!the circuits and then fit them all at once intothe synthesizer or build and add themPiecemeal_ As the booklet is intended moreas a reference work than a fiat instructionmanual. the chapters can be read in airyorder. The booklet lin photocopy form)assumes reasonable tarniaritv with com-puter technologyIN PHOTO -COPY FORM Price: E1.60
33 ELECTRONIC GAMESA selection of . which give as muchenjoyment in ro them as actuallyplaying the a., The circuits are
t -e electronics invokedare not e, -_therefore anyone with agood soldering eon wit find this book satis-fying. Thew are electronic games that donot need a TV screen. and as a result can beplayed just about anywhere_
Price: E4.80
AUTOMATE YOUR MODELRAILWAYSeance a: tater most railway modellers areconfronted with the problem that their modelraaway has become so e,tertSit.-e that it cani- re :enrolled with The
problem is Par;----cately. And that- electronics! This book win
ler step by step through theof electronic controls. Fast. it
:n a power controller, then with thecertrol turnouts, nnt Cock protec-tion system. and f . =nosh howto control your entire fa with acomputer. By trued., the necessaryelements yourself, onus--; -an be kept at areasonable level. Eac!7 7.e of constructionis complete within , mat you :an stopat the level of autorra. reached in thatstage
Price E625
COMPUTERS
TV GAMES COMPUTERThis book, provides a [efferent - and, inMany ways, easier - approach tomicroprocessors. The TV games computer adedicated to one specific task. as the namesuggests_ This provides an almost uniqueopportunity to have ltin white learning,
Price: 17.10
SC/MPUTER 111Describes now to build and operate yourown microprocessor system - the first bookof a series - further books w0 show howthe system may be extended to meet variousrequirenKtntS-
Price: £5.80
SC/MPUTER I21The second book in series. An updated ver-sion of the monitor program 'Mug III isintroduced together with a number of expan-sion possantires By adding the ElekterminalTO the system described in Book 1 themicrocomputer becomes even more vet -Sant?
Price: E5.80
JUNIOR COMPUTER BOOK 1For anyone no to t...e,:...erne tarr.;:ar ruthImicrolcomputers. dis book gives theopportunity to buid and program a personalcomputer al a very reasonable cost.
Price: 16.90
:
HANDS OFTMY BIKE!
7 5 IT for7-Pereez A -4.ekt .
i-e4
301 CIRCUITSThe !rock .5 a continuation of our popularand very successful 300 circuits publication_It is composed of 331 assorted circuits rami-e -re from sere* to mere COmpiert designs.described and explaired n straightforwardlanguage
Price: £6.80
302 CIRCUITSThe latest in etektor Electronics' popular 300series of books offers you 3132 neve and prac-tical applications taken front the whokgamut of electro- wee over 300 pagesyou wet find, circuits for aria video; Car, eyrie.
arid moto.e. me and garden;receivers a rot ae s Oobies and games:measuring aria - cool:Wpm andgenerators: curre,.. -aLrCe and powersupplies: microcornrhiters and elec-uophonics; and a miscellany of otherinteresting subjects:
circuits that you probably have been look.mg for and which you can now adoptwithout airy problems:
circuits that vs61 give you sparking needfor all sorts of appecatians.
cncuns is the prime source of ideas foe allwhose profession or hobby or life or atthree - is electrooil
Price: E6.130
ELECTRONICS STEPBY STEP SERIES
PROJECTS FOR YOURHOME WORKSHOPOCeaaliLte_-i to rha,a stati.-red power sup-plies. a multitude of test equipment, and asoldering iron thermostat.
Price E4.95
PROJECTS FOR CARS ANDBICYCLESshows how to a tel ezonono indi-cator. choke alarm, frost warner. automaticbicycle fghts. exhaust gas tester, rev fightsmonitor, ant, theft alarm
Price E4.95
PROJECTS FOR AMATEURPHOTOGRAPHERSceriarhes hay. to a battery tester, lghtmeter, {rococo timer, electronic flash, darkroom d tat. slave flash unit, enposuretimer.
Price £4.95
PROJECTS FOR HOME ANDGARDENshows how to male a baby alarm, draughtdetector, kit meter. rr*didne cupboardsafeguard, temperature &...arrn, Peep/woeamplifier. house plant protector. univerwlalarm Mstallation
Price E4.95
MISCELLANEOUS
DATA SHEET BOOKWert at i2S! the boo; that designers havebeen v. -a,!- ': Eoktor Data SheerBook. fr you a CMOS. aLinear, St000 and Audis DataBook: emenswe information on 269 of themost important IC's. A very useful and ecere°mica! reference book!
Price: £8.40
TO ORDER. PLEASE USE THEPOSTAGE -PAID ORDER CARDAT THE BACK OF THIS ISSUE.
EEFebruary 1986
42
MULTI -BASICfor the BBCMicrocomputerMULTI/BASICfor theCMS6502systemCambridge Micropro-cessor Systems Limitedhave announced MULTI-
BASIC, a comprehensivecontrol language for theCMS6502 Industrial Con-troller. Already used exten-sively in the mostdemanding industrial en-vironments, it allows BBCBASIC users to write andrun event -driven multi-tasking control programs.Support is provided in twonew books: MULTI -BASIC -a comprehensive controllanguage for the CMS6502system, and MULTI -BASIC-multi -tasking BASIC /orthe BBC microcomputer. Itis hoped to give a fullreview of these books in afuture issue of Elektor Elec-tronics.Cambridge Micropro-cessor Systems LimitedUnit 18Industrial EstateChelmsford RoadGreat DunmowEssex CM6 1XGTelephone: (0223) 324141
NewcataloguesNote that catalogues listedhere may not be free ofcharge although many ofthem are. Furthermore, not
all businesses publishing acatalogue are prepared toaccept orders from otherthan professional orbusiness customers
EMS UK Limited hasreleased a new, full -colourcatalogue of press -fit stan-dard VME bus backpanels.The catalogue gives com-plete information as tosizes and tolerances, aswell as details of EMS'scustom backpanel manu-facturing capability. Forfurther information contactRussell Ward or DerekWhittington atEMS UK LimitedBray HouseMartin RoadCordwallis Industrial EstateMaidenheadBerks SL6 7DETelephone: (0628) 76062
The recently publishedRoss 1986 Trade Cataloguelists more than 370 items in15 product rangesmarketed by London -based Ross Electronics,including no fewer than 42new products. In additionto Ross's main line ofstereo headphones, awide range of new audioand video leads, micro-phones, micro loud-speakers, home computerinterfaces, cassettes andaudio accessories, inter -corns, plubic addresssystem equipment, homesecurity devices, serviceaccessories, tools, andmultitesters are alsoincluded.Ross Electronics49-53 Pancras RoadLondon NW1 2QBTelephone: (01) 836 1072
After 25 years of successfultrading, H.T. ELECTRICAL Ltdhave published the firstissue of their newcatalogue. In almost 300well -illustrated pages, theuser is offered a wealth ofinformation on a largevariety of electrical
systems, control gear,enclosures, and test instru-ments. It is worth notingthat H.T. ELECTRICAL haveeight nationwide outlets,including a Scottish div-ision. A computer networklinks these divisions, sothat instant accessthroughout the UK for stockavailability, price struc-tures, and account detailsis ensured.H.T. ELECTRICAL LTDGibbons Industrial ParkDudley RoadKingswinfordWest Midlands DY6 8XFTelephone: (0384) 288504Telex: 335458
A new 76 -page short -formdata book, Products '85,describing analogue,digital, gallium arsenid,and custom integrated cir-cuit products is nowavailable from Harris Semi-conductor.Each section of the bookprovides an individualproduct descriptionincluding technicalspecifications and pin -out.Standard productshighlighted in the book in-clude CMOS digital prod-ucts (8- and 16 -bit micro-processors and periph-erals, RAMs, PROMs, com-munications ICs, busdrivers, programmablelogic, and standard cellcapability): bipolarPROMs; analogue prod-ucts (opamps, voltagereferences, comparatoranalogue switches, DASsignal processors, AID andD!A converters, sample -
and -hold amplifiers, andmultiplexers).Harris-MHS SemiconductorEskdale RoadWinnersh TriangleWokinghamBerks RG11 5TRTelephone: (0734) 698787
The Autumn Updata ofToolrange's Catalogue1985 is now available.Toolrange LimitedUpton RoadReadingBerks RG3 4JATelephone: (07340) 22245Telex. 847917
devices, tools, racking Teleoperationand Robotics:ApplicationsandTechnologyby Jean Vertut andPhilippe CoiffetISBN 0 85038 962 3Price £32.50Teleoperation concernsthe exploration and ad-vanced exploitation ofspaces which, because oftheir inaccessabilily orhostility are generally for-bidden to man. Volume 3Bin the Robot Technologyseries, Teleoperation andRobotics: Applications andTechnology, just publishedexamines this discipline indetail.Kogan Page120 Pentonville RoadLondon NI 9JNTelephone: (01) 837 7851-4Telex: 268048
The LinCMOSDesign Manualby David DalePrice £5.60 plus £1.50 p&pTexas Instruments haspublished The LinCMOSDesign Manual whichdescribes their range oflow power linear CMOSoperational amplifiers,timers, and comparators. Italso shows how these maybe applied in analoguecircuits and systems.After an introductoryoutline of the LinCMOSprocess, a comparisonwith other types of oper-ational amplifier and asummary of the benefits ofLinCMOS, the book pro-vides a review of thedesign characteristics.The application sectiondescribes a variety ofamplifiers, a voltage regu-lator, a Schmitt trigger, os-cillator circuits. and activefilters.Timers and comparatorsfollow in separate sections,and the volume is com-pleted by data sheets forall the products in therange, in the traditional TI
43 EE
February 1986
data book format.The author, David Dale, isa senior applicationsengineer in the linearproducts department atTI's Bedford plant.
The BIFET DisignManualPrice £3.95 plus £1.50 p&pThis valuable referencework for a wide range ofanalogue circuit and
miscellaneous circuits.For each application itgives a full circuitdiagram, design equa-tions, and a description ofthe circuit operation. Inmany cases, the deri-vation of the design equa-tions has been providedto help understanding ofthe circuit operation.An introduction outlinessystem designs containssections in sampling, am-plification, filter, and oscii-lator circuits, as well as
data on individualdevices and a section onthe production of BIFETdevices, which use bothJFET and bipolar transistorson a common substrate.Texas Instruments LimitedP 0 Box 50Market HarboroughLeicestershire
'TERS LETTERS LETTERS LETTERSDear Sir-Do you have apast or present project todecode Teletext? Ideally Iwant hard copy for myDragon (6809 -based), butthis is not essential.
P G DAWSONLONDON SE25 6TG
A Teletext Decoder waspublished in three parts inour October Novemberand December 1981issues. Unfortunately, backissues or PCBs for this pro-ject are no longeravailable. Photocopies ofthe relevant articles can,however be suppliedagainst your order Ed.
Dear Sir-Please advisewhere I can get theTDA3810, ZN414E, andZN415E, as used in thePseudo Stereo, FM PocketRadio, and Ligth PoweredRadio. Also please statethe cost of the solar cells.
NARENDRA G KHARADEBOMBAY UNIVERSITY
The TDA3810 is o Mu/lard(Philips) product, while theZN414E and 415E aremanufactured by Ferranti.Unfortunately, we cannotadvise you on Indianstockists but Elek/or Elec-tronics India (Telephone:Bombay 369478367459)may be able to help onthis The cost of the solarcells varies from supplierto supplier but should beabout £1.50 (averageprice in western Europe) or
$1.90 (average price inNorth America). Ed.
Dear Sir-I have been try-ing to track down a circuitwhich will receive and dis-play the international timesignal as transmitted bythe Rugby radio station.
C NEWBOULDBANBURY
A circuit that will meetyour requirements pre-cisely was published inour May and September1982 issues respectively.The first describes theclock and display, whilethe second deals with thereceiver for the Rugbylime signals. Unfortunately,the May 1982 issue is nolonger available, nor arethe printed circuitsPhotocopies of the two ar-ticles can, of course, besupplied against yourorder Ed.
Dear Sir-In my business Ioften encounter problemsof an electro-mechanicalnature. My partner and Ican usually cope with themechanical part, but theelectrical electronic partis generally beyond us. Aswe are both avid readersof E/ek/or Electronics, Ishould like to contactsome of the contributingdesigners whose skills weboth admire. Furthermore,would you grant a licencefor the industrial use ofpublished material of
which you own thecopyright?
P A WILSONST ALBANS
Most of the constructionprojects published by usoriginate in-house, i.e., thedesigners are members ofour staff None the less, dolet us know of specificwork you have in mind, sothat we may considerfurther action. Ed.
Dear Sir-I should bepleased to hear from youwhether the PCB designsnormally published inyour centre -fold are sub-ject to copyright, at leastthat is what the relevantstatement on your titlepage seems to indicate.
A W RONYWTTERWORTH
Copyright in respect of ourprinted-circuil boards ap-plies to their beingreproduced other than forone's own personal use.We are, however alwayswilling to discuss deviatingfrom this rule under cer-tain circumstances, soplease let us know whatyou have in mind. Ed.
Dear Sir-I should bepleased if you advise mewhere I can obtain theType TGS109 sensor used inproject 72 of your Summer
Circuits 1985 issue.
P R ALLENLINCOLN
We have had a number ofenquiries on this smokeand gas detectorpresumably because theoriginal UK supplier hasgone out of business. Theonly alternative source wehave been able to find is:MXE Engineering Vondel-loan 75 Postbus 1163840 AC Harderwijk TheNetherlands Telephone(3410)12486'16487 - Telex40374. Ed.
Dear Sir-I have beenunable to obtain the20x10 mm solar cells usedin the Light -powered Radiopublished in your April1985 issue, which, Iunderstood, wereavailable from Forest HillElectronics Inc. NY.
D 0 LOCKTONCANBERRA
Sorry to hear your troublesUnfortunately, we cannotadvise you on anyAustralian supplier ofthese devices. Howeverthe largest stockist inwestern Europe we know ofis Deisseldorler ElektronikVersand - Kirchfeldstrasse48 - 4000 Diisseldorf-f -
Federal Germany Tele-phone (211) 379373. Theycon supply cells from5x25 mm up to 100 mmdiameter Ed.
EEFebruary 1986 44
Back -lightviewer for PCBinspectionA simple, low-cost solutionto the need for inspectionof printed -circuit board,PCB, tracks, and especiallythe copper deposits inplated -through holes, PTH,is provided by a back-light microscope fromCUEL, which incorporatesa throat for PCBs and a lo-cation slot for PTH sections.The back -light viewermicroscope gives a x40magnification, with adjust-able focus, and it has a3 mm field of view Illumi-nation is provided by anM42 -type quartz -halogenlamp, which, rated at10 W, has an average ser-vice life of 1000 hours.Power is derived fromeither four internal D -sizebatteries or a mainssupply.
CUEL12 Tulip Tree AvenueKenilworthWarwickshire CV8 2BUTelephone: (0926) 54293Telex: 311248 (LPS:3382:3)
New sub-miniatureswitchesThe Otto B3 Series of sub-
subminiature double -break, snap -actionswitches has recentlybeen announced byDiamond H Controls.Available in a choice offour standard terminalstyles, including straightand right-angle PC pins,turret, and wire -wrap, the
B3 Series has a bluediallyl body that is, de-pending on type, 0.156 or0.200 in. wide. The doublebreak, dual circuit ter-minals are manufacturedin brass and are gold -flashed. Electrical life atfull load is 100 000 cycles.
Diamond H ControlsLimitedVulcan Road NorthNorwich NR6 6AHTelephone: (0603) 452919Telex: 975163 (3382:19:F)
Custom-mademembrane-
switch panelsHighly reliable, long-lasting membrane -switchkeyboards can be custom -designed for particularapplications by DiamondH Controls of Norwich.These units allow a wipe -clean front panel to becreated which is in-herently sealed againstliquids, dust, and othercontaminants. They incor-porate a tough polyestermembrane which is saidto be unaffected by mostsolvents and all but thestrongest acids andalkalis. Switches are touch -sensitive (with an ac-tuating force which canbe varied to suit re-quirements), and tactilefeedback can be pro-vided as an option.The simplicity of themembrane -switch concept
is said to provide a work-ing life some ten timeslonger than that normallyexpected for mechanicalswitches. They are conser-vatively rated at aminimum of 107 operatingcycles.A variety of circuit designscan be incorporated, andswitches can interfacefunctionally and elec-trically with all types ofcontrol logic. The manu-facturer is also able toprovide switch panels withwindows for LED indicators,and both LCD and LEDdisplays.
Diamond H ControlsLimitedVu/can Road NorthNorwich NR6 6AHTelephone: (0603) 45291Telex: 975163 (LPS:3382:1)
Sealed long -liferechargeablebatteriesA range of sealed -for -liferechargeable batteries,designed primarily for useas standby power suppliesfor electrical or electronicequipment, is availablefrom Tungstone Batteries.These Challenger batteriesare sealed for life. Sincethey never need toppingup and do not, even ifseverely damaged, leakacid, no special pre-cautions need to be takenregarding their use. Theyare claimed to take 70 per
cent less space and toweigh 60 per cent lessthan Plante cells. With thebox and lid made fromrobust flame-retardant ABS-thermoplastic- the unitswill withstand stress, ther-mal shock, and vibration.Even if the container andlid are broken, the batterywill continue to providepower for some time.Sizes available are 2C120;2C150; 2C225; 2C275;2C280; 2C300; 2C320:2C350; 2C400; 6C60;6C100; 12C36; and 12C48.The number before the Cis the voltage and thatafter is the capacity in Ah.Life of the batteries isclaimed to be 10 years.
Tungstone Batteries LimiledMarkel HarboroughLeicestershire LE16 9EZTelephone: (0858) 65161Telex: 34305 (LPS:3382:4)
New line of5x20 mm fusesA new line of 5x20 mmfast -acting fuses, includingUL!CSA and SEMKOIVDEversions, has been in-
troduced by the BussmanDivision of Cooper In-dustries, the world's largestmanufacturer and supplierof circuit protectiondevices for the electrical,electronic, and automotivemarkets.
Bussman UKI Drumhead RoadChorleyLancs PR6 7BXTelephone: (02572) 69533Telex: 67478 (3382:11:F)
45 EEFebruary 1986
ISO standardsfor opensystemsA software package fromLDR Systems enablestelecommunications users-large and small- andsystems builders to designand install communi-cations networks contain-ing many different types ofcomputers. It is believed tobe the first ever packageto provide independentimplementation of ISOstandards for open systemsinterconnection.The Isonet package canbe implemented within avery short time on mostcomputers from micros tomainframes and. while it is
written mainly in ISOPascal, a -C.' version isalso available.The package comprises anumber of building blocksthat provide the variousservices and protocolsdefined for open systemsconnection by the Inter-national StandardsOrganization. It can alsomake possible the inter-connection of Local AreaNetworks -LANs- acrossWide Area Networks-WANs- with the use ofX.25 protocols.The product is alreadyavailable for the IBM-PCand a number of com-patibles. including theOlivetti M24 and theEricson -PC. while it willalso run on the BurroughsB20 range. the DEC VAX -11,and the ACT Apricot andSirius. 11 will shortly be re-
leased for the PDP-11 andStratus computers. CP M86,MS-DOS and ConcurrentDOS versions have beenimplemented and a Unixversion is also due for re-lease shortly.
LDR Systems LimitedAsh ValeAldershotHants GU12 5BBTelephone: (0252) 331666Telex: 858393 (LPS:3382:9)
New PCMtranscoderA new telecommuni-cations IC, the TypeHC -5560, from Harris per-forms all transcoder func-tions, including linecoding, line error monitor-ing, and correction of DCwander and timing jitter.Unlike preset discrete IC ormode -limited transcoderdevices, the HC -5560 pro-vides user selection of allline coding and decod-ing schemes for NorthAmerican and Europeandigital transmission tele-phone lines. The deviceoperates from a single 5 Vsupply and draws a cur-rent of not more than100 mA.
Harris MHS SemiconductorLimitedEskdale RoadWinnersh TriangleWokinghOMBecks RG11 5TRTelephone: (0734) 698787
(3382:22: F)
SINGLE5\/ SUPPLY
-
MODE SELEC.T ABI
- AMI (T1)- Ban (T1)
TION G
- HOB3 (CCITTECOMMENDA- B6ZS (T2)
NORTH AMERICANAND EUROPEAN
SIMULTANEOUSENCODING
AND DECCOMPATIBILITY
ASYNCHRONOUSOPERATION
LOOP BACK CONTROL
TRANSMISSIONERROR DETECJI01\
NnICATIONSIGNAL
A11 f\-\1\- nr-IM T
1 t , is
NCA-OD
1
II
IC socket lineexpansionAries Electronics has ex-panded its range of ColletEject -A -DIP Sockets with theintroduction of several ad-ditions to its family.
One of these additions isa 28 -pin socket on 0.600in. centres (see illustration),offering gold collets andtin shell for 28 porn ICs,while another is a newlocking arm which is thecorrect height for most ICpackages.
Aries Electronics (Europe)Allred House927 Oallands DriveWeybridgeSurrey KT13 9LBTelephone: (0932) 57377Telex: 934830 (3382:20:F)
New range oftest instrumentsWest Sussex Instruments
can now offer an in-teresting range of test in-struments, including (a)Megohmmeter Mk VI at£62.50; (b) RCC8 Tester at£79.50; and (c) Loop Testerat £86.00. All these instru-ments come complete ina black flip -top carryingcase with shoulder strapand all necessary plugsand leads. All threecomply fully with the 15thedition of the relevant IEERegulations.
West Sussex InstrumentsLimited12A Coronation BuildingsBrougham RoadWorthingWest Sussex BN11 2NWTelephone: (0903) 212303Telex: 877159 (3382:17:F)
EE
February 1988 46
Advancedminiature hi-fispeakersAdvanced miniaturespeakers with harmonicdistortion figures only onetenth that of conventionalunits are available from DJordan. The moving coilloudspeakers, measuring80x70x45 mm, cover thefrequency range of 150 to22 000 Hz (treble unit) or 30to 200 Hz (bass unit). Powerhandling is up to 50 W.The cone and coil formerare developed from alight metal alloy chosenfor its very high rate ofrestoration. The cone is ter-minated at its peripheryby a roll surround con-sisting of specially for-mulated laminate film tocombine optimum absorp-tion properties with vir-tually zero axial stiffness.The loudspeakers can besupplied in 1.5 litrecabinets or by themselvesfor DIY enthusiasts ortraders who wish to putthem in their ownhousings.
D Jordan (MiniatureLoudspeakers) MfgSydney CollagesCores End RoadBourne EndBucks SL8 5HYTelephone: (06 285) 29441
(LPS:3382:8)
0.1 in, pitchjumper linkWells Electronics haslaunched the Series 480insulated jumper link forstandard 0.025 in. squareheader posts on 0.1 in.
centres. Jumper links areused for making on -boardconnections between pinson PCBs, for example, forbusing, programming,and switch replacement.
Samples and stock quan-tities are available from:Dage (GB) LimitedEurosem DivisionRabans LaneAylesburyBucks HP19 3RGTelephone: (0296) 33200Telex: 83518 (3382:23:F)
New 'D"subminiatureconnectorMidland -Ross have re-cently introduced a newright-angle D subminiatureconnector, which providedan improved method if I/Opackaging for the com-puter, telecommunications,and instrumentation in-dustries. Ruggedly de-signed, meeting ULflammability requirements,the new TR 6850 Series isfully compatible with otherleading manufacturers'products. The connector isavailable in 9, 15, 25, and37 contact configurations.
It has fully insulated pinsfor fast, easy insertion intoprinted -circuit board&
Midland -Ross LimitedElectronic ConnectorDivisionI Duke StreetReadingBerks RG1 4LNTelephone: (0734)500051Telex: 849992 (3382:16:F)
SoftwareprotectionUnauthorized copying ofsoftware can be stoppedwithout preventing back-up copies being made,and without confining thesoftware to a singleworkstation.
An ID module, developedby the Swedish companyM Bejting AB, offers copyprotection by an elec-tronic key, which connectsthe software to a specialmodule in the computer.
The module consists of asmall PCB that is pluggedinto one of the computer'scard slots. It contains aunique code withoutwhich the software cannotbe used.
Ingenjoirslirman M BellingABMarkvardsga/an 115-113 53 StockholmSwedenTelephone: +46 8-311780Telex: 11998 Beflab S
(3382:21:F)
Four -in -oneplugThe first four -in -one 13 Aplug has been introducedby Duraplug ElectricalsLimited. Called theMultiLine Plug, it enablesup to four appliances tobe connected to a singlesocket outlet without theneed of additional plugsand adaptors. The unit isavailable in black orwhite and is constructedin a tough thermoplastic,which is highly resistant toimpact.
Duraplug ElectricalsLimitedWestwood WorksMargate RoadBroadslairsKent CHO 2QLTelephone: (0843) 68771Telex: 965373 (3382:12:F)
47 EEFebruary 1986
Low-cost pagerA no -frills radio pagingsystem, which is easy to in-stall and has a range ofup to 800 metres. isclaimed by its makers,Barkway Electronics Ltd, tocost 30 per cent less thancomparable systems.The Micropage system isdesigned to bleep peoplewho are constantly on themove, and a receiver canbe called automaticallyby a remote contact suchas a door bell, alarmsystem, fault monitor, orany on loff switch on anelectrical appliance.The Micropage transmitter.encoder, and aerial arecontained in a compactdesktop unit measuring220x160x70 mm. It will callup to twenty receivers,although it is said to becost-effective with only two.The pocket receivermeasures only100x60x60 mm, andweighs 30 g includingbatteries (which can pro-vide power for up to ayear with normal use).
Barkway ElectronicsLimitedMelbourne Science ParkMelbourn, RoystonHefts SG8 6EJTelephone: (0763) 62222Telex: 817651 (LPS:3382:5)
Crimp sub-miniatureconnectorsSuhner Electronics Limitedhave introduced a newrange of subminiatureconnectors that have full
crimp and comprisesthree types: SMB -snap -onmechanism; SMC -screw -on mechanism; and SMS-slide -on mechanism. TheSMC type is suitable forapplications up to 10 GHz;the other two up to 4 GHz.All have 50 ohms im-pedance, and aresuitable for cables withelectric diameters of up to1.65 mm.Suhner Electronics are theonly company in the UKsupplying full crimp SMCand SMB subminiatureconnectors.
Suhner Electronics LimitedTelford RoadBicesterOxfordshire OX6 OLATelephone: (0869) 244676Telex: 837615Fax: (0869) 249046
(3382:24:F)
Permanentmemory chipfor
applicationsThick film pre-pro-grammed memory-PPM- devices, suitablefor use in identificationsystems and transponders,offer space, cost, arid per-formance advantagesover similar componentsmanufactured previouslyon double -sided PCBs.Possible uses include theidentification of animals,production line items, lug-gage, electronic locks,and identification tags forpersonal use. They canalso be used in personal
11111
paging equipment, andattached to movingvehicles of all types.The use of thick filmcermet materials onalumina ceramicsubstrates permits the pro-duction of a very -high -capacity matrix in a smallarea. For example, withparallel conductors of0.25 mm line and spacewidths, a 16x16 matrix canbe accommodated on a1 cm' substrate with roomfor terminals on all foursides, and it is possible tosimultaneously fabricate150 PPMs on a150x100 mm aluminawafer.The matrix can bemanufactured separatelyand added as a surface -mount component, or itcan be fabricatedtogether with the thick -filmcircuit on the samesubstrate.
Welwyn Electronics Limited8edlingtonNorthumberland NE22 7AATelephone: (0670) 822181
(LPS:3382:2)
Televisionswitching unitA high-performance low-
loss switching unit, whichgives instant selection ofone of three inputs to atelevision set, is availablefrom Elkay Electrical. The3 -way video switch, whichmeasures 100x50x23 mmand weighs 80 g, can beused to link, for instance,video recorder, computer,and electronic game tothe TV set.If an aerial is pluggedinto the unit, which is de-signed to overcome prob-lems of picture degra-dation associated withlow -quality splitters andswitches, three televisionsets can be operated fromit.
With a frequency range of
48 to 960 MHz, the switchcan also be used forclosed-circuit operation,security systems, andlinkage of studio monitors.
Elkay ElectricalManufacturing Co.Mochdre Industrial EstateNewtownPowys SYI6 4LFTelephone: (0686) 27000Telex: 35505 (LPS:3382:6)
Low -profilemodemtransformerA line -matching trans-former from ElectronicTechniques has the lowprofile demanded byequipment with small PCBseparations, while offeringevery feature needed bymodems providing datacommunication overpublic telephone lines.The P1200 unit measuresonly 14.5x18x18 mm andyet meets the high degreeof isolation and safetystipulated by the BritishStandards and BABTtelecommunicationsauthorities who call formandatory safety featuresnormally associated onlywith mains powertransformers. The P1200achieves this without detri-ment to telecommuni-cations performance andmay be used to connectany data-processingequipment to PIT lines.
Electronic Techniques(Anglia) LtdViking WorksKirtonIpswich /Pf0 ONXTelephone: (03948) 433
(1PS:3382:7)
EEFebruary 1986
48
REGULATORS.M 317T Plastic 10220 variable £ 1.00_M 317 Metal £2.207812 Metal 12v 1A £ 1.007805/ 12/ 15/24 plastic 50p 1000 /18p7905/ 12/ 15/24 plastic 50p 1000 + /20pCA 3085 TO99 Variable regulator 1.00J. 723 14 dil 50p
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£ 2.002716 USED, WIPED Er VERIFIED .. _ £2.002708 NEW £ 2.502732 EX EQPT £ 2.50 NEW £ 3.002114EXECIPT6Op 4116EXEOPT70p10 - 60p4164-200n5 E 1.50 10 £ 1.20S264LP-15 8K STATIC RAM £ 3.80
POWER TRANSISTORSTIP 141, 142. 147 ea. f 1.00TIP 112, 125. 428 2 E 1.00TIP 35B . £ 1.30 TIP 35C £ 1.50SE9302100VI0ADarlsimT1P121.._ 2 £ 1.002N31355 Motorola 50 p 5 £2.002N3055 Ex eqpt. tested 4.'£ 1.00Plastic 3055 or 2955 equiv. 50p 100 £30.002N3773 NPN 25A 160V... £1.80 10'E16.00
DISPLAYSutaba 4 digit clock fluorescent display
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4.00 (E 1.50115.000pF 40V SPRAGUE 36D
2.50 1£ 1.50)1.25" Panel fuseholders 5/£1.00STAINLESS STEEL HINGES 14.5" by 1"noen each £1.00 10£7.00Mains transient Suppressors 245 V 3 £ 1.00TOK KEY SWITCH 2 POLE 3 KEYS_teal for car/home alarms . f 3 100/£ 2.0012 v 1.2 w small wire ended lamps/fit Audi/VW/ TR7 /Volvo/ SAAB . 10/f 1.00Heat shrink sleeving pack £ 1.00?TFE sleeving pack asstd. colours _ £ 1.00250 mixed res. diodes, zeners £ 1.00Mixed electrolytic caps. 100, E 2.00Stereo sass. R/P head E 2.50Mono head .. £ 1.00 Erase head .. 50pThermal cut-out 50°, 77°C, 85°C. 120°C80PThermal fuse 121°C 240 v 15 A 5, £ 1.00PCB pins fit 0.1" Vero 200 E 1.00TO220 Micas bushes 10 50p
100 £ 2.00103 Micas bushes 20.'E 1.00Relays 240 v AC coil PCB mounting2 pole changeover £ 1.003 pole changeover E 1.00
8 mains cassette leads 3/£ 1.00,-",YNAR wire wrapping wire2oz reel £ 1.00'TFE min. screened cable _ _ .. 10 m/E 1.007okin mains rfi filter 250 v 15 A .... £ 3.00Mercury tilt switch small E 1.00min. rotary sw.-tp c/o 1/8" shaft 21£ 1.00Thorn 9000 TV audio o/p stage 2/£ 1.0010M7 CERAMIC FILTER ... 50p 100/£ 20Ern ar 9m CERAMIC FILTER
50p 100/£ 25
240 v AC FAN 4.6" SQUARENEW £ 5.50 (f. 11240/115 v AC FAN 4.6" sq. NONE 7.00 (£ 1)
BELLING -LEE 12 way blockL1469 4/£ 1.00POTENTIOMETERS short spindle2k5 10k 2m5 lm lin 25k log 5/£ 1.00500k an 500k log long spindle 4/£ 1.0040 kHz ULTRASONIC TRANSDUCERSex. eqpt. NO DATA pair £ 1.00Stick -on cabinet feet 30/£ 1.00TO3 transistor covers 10/£ 1.00
transistor mounting pads T05/1018 £ 3/1KDIL Reed Relay 2 pole N/0 contacts £1.00
RECTIFIERS120 v 35 A stud 65p12FR400 12 A 400 v small stud ... 4 £ 1.50BY 127 1200 v 1.2 A 10 £ 1.00BY 254 800 v 3 A 8 £ 1.00BY 255 1300 v 3 A 5 E1.001 A 800 v bridge rectifier 4 C 1.006 A 100 v bridge 50p10 A 200 v bridge 1.5015 A 100 v bridge 1.5025 A 200 v bridge ea. £ 2.00 10,f 18.0025 A 400 v bridge £ 2.50 10'E 22.00
SCRsMCR72-6 400 v £ 1.00BTX95 800 v 15 A £1.5035 A 600 v stud £ 2.00MCR106 equiv. 4 A 400 V 40p2N5061 800 mA 60 v TO92 4 £ 1.00TICV 106D .8 A 400 v T092
3/E 1 100 £ 15.00MEU21 Prog. unijunction 3 £ 1_00
TRIACSdiacs 25pTXAL225 8A 400V 5 mA gate _ 2 E 1
100 35.0025A 400V ex eqpt_ tested £1.50
CONNECTORS(EX EQPT_ price per pair)'CY 9 way £ 1 15 se.ray £ 1.25 25 way £ 237 way £2 50 way E 3.50 covers 50p ea.NEW 25...ray PCB skt £ 1.00D9 PCB PLUG 90 deg. £ 1.500.1" d'sided edge connector, 32 way,ideal 2X81/ SPECTRUM £ 1.500.1" d; sided pcb plug 24 25 way £ 1.502 pole sub mirt. connectors ideal radio controlRS46614721488/343 5 pairsl£ 2.00
IDC CONNECTORS25 way Plg/Skt 37 'D' PLUG ea. £ 2.0020 way socket (BBC user port) £ 1.0026 way socket (BBC printer) E 1.5034 way socket (BBC disc drivel 2.0040 way socket E 2.00
WIRE WOUND RESISTORSW21 or sim. 2.5 W10 of one value for E 1.001RO, 2R0, 2R7, 3R9, 5R0, 10R, 12R, 15R,18R, 20R, 27R, 33R, 36R, 47R. 120R. 180R.330R, 390R, 470R, 560R. 680R, 820R, 910R,1K15. 1K2, 1K3, 1K5, 1K8, 2K4. 2K7, 3K3,10KW22 or sim. 6 watt7 of one value for £ 1.00R47, IRS, 9R1. 10R. 12R, 20R. 33R, 51R.56R. 62R, 120R, 180. 270R, 390R, 560R.620R, 1K, 1K2, 2K2. 3K3, 3K9. 10KW23 or sim. 9 watt6 of one value for £ 1.00R22, 1R0, 3R0, 6R8. 56R. 62R, 100R. 220R,270R. 390R, 680R, 1K, 1K8, 10K
W24 or sim. 12 watt4 of one value for £ 1.00R50, 2R0, 10R, 18R, 47R. 68R. 75R. 82R,150R. 180R, 200R, 270R. 400R, 620R, 820R,1K.
KEYTRONICS332 LEY STREET, ILFORD, ESSEX IG1 4AF.
Shop open Mon -Sat 10am-2pmTELEPHONE: 01-553 1863
PHOTO DEVICESSiottea opto-switcn OPCOAOPB815 C 1.302N5777 50pTIL81 TOI8 Photo transistor £ 1.00TIL38 Infra red LED C. 50p
100 £ 25.00OP12252 Opto isolator 50pPhoto diode 50p c £ 2.00MELI2 (Photo darlington base n/ci 50pRPY58A LDR 50p ORP12 LDR 85pLEDs RED 3 mm or 5 mm 12.'£ 1.00
100/E 6.00GREEN YELLOW 3 or 5 mm 10/£ 1.00
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MULTI TURN PRESETS10R. 20R. 100R, 200R. 500R. 1K, :=Up2K. 5K, 22K, 50K. 100K, 200K. 1M.
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SOLID STATE RELAYS NEW10 A 250 V ACzero voltage switchingcontrol voltage 8-28 V DC E 2.50VARIAC 0 to 130 V 6 Anew uncased £ 12.00 1E2 5/3
POLYESTER/POLYCARB CAPS.1n/3n3/5n6/8n2 1% 63V 10mm .1001£6.0010n/15n/22n/33n/47n/68n10 mm red 100 C 3.0010On/250 V radial10 mm 100E 3
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BEAD THERMISTORSGLASS BEAD NTC Res at 20'_250R. 1K2. 50K. 220K. 1M4R53 Thermistor
[-LOD
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49 EE
February 1986
This sixth article in the series deals with the colourextension, which is basically a large amount of extraRAM (Random Access Memory) for the main(monochrome) card One extension is sufficient for up tosixteen colours on two or four screen pages.
HIGH -RESOLUTIONCOLOUR GRAPHICSCARD -6The colour extension card containsthree identical sections, each com-prising a 64 Kbyte memory bank; ashift register; RMW circuitry; andcolour decoding logic for memorywrite operations. In theory, anynumber of extensions could beadded to the main card, but in mostpractical cases one will suffice toprovide up to sixteen colours.
Adding anintensity bitIn the very first part of this series,published in the September 1985issue of Elektor Electronics, blockschematic diagrams of themonochrome and full colour systemswere presented in Figures la and lbrespectively. For reasons of clarity,Fig. lb then showed an 8 -colour RGBconfiguration with three memoryplanes. However, with a completedmain card and an extensionavailable, four memory planes in allare at the user's disposal for storageof pixel attributive information. If thefourth bit is used to supply pixel in-tensity information in addition to theRGB bits already mentioned, sixteeninstead of eight pixel colours be-come available. It will follow thatwith n memory banks installed, thenumber of available shades of colouris 2n.As already pointed out in previousarticles, every dot on the screen cor-responds to one bit in the GDP RAMmemory. If this bit is at a high logiclevel, the dot will be dark, whereas alogic low level will light it. As for apixel, three of these dots (bits)specify its colour one bit controlsthe red electron beam inside themonitor picture tube; the second,the green beam; and the third, the
by P Lavigne 8-D Meyer
EEFebruary 1986
50
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lv
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Fig. 27 Circuitdiagram of thecolour extensioncard.
blue beam. In addition to these RGBbits, a fourth bit may be added to ef-fect beam intensity modulation.When this intensity bit - I - is lowfor a given colour, one of the monitorvideo amplifier stages is arranged toinvert the signal, which results in ahalved output amplitude. When the Ibit is high, full amplitude is pro-vided, and the relevant colour willappear with 'normal' intensity.The above discussion, however, is byno means to be understood as anobligation to limit the use of this ad-ditional bit to intensity modulation; itmay also function to blink colours inspecified screen locations, or to in-vert certain colours. With some skill,highly interesting effects may thusbe realized. and a possible furtherarticle in this series will deal withsuch special applications. For now,
the fourth bit makes it possible touse the full colour capability of aRGBI monitor.
Circuit detailsIn addition to the circuit sectionsalready mentioned (memory banks,shift registers, RMW circuits, colourdecoding logic), the present exten-sion card has a local addressdecoding section, along with awrite -only register for colour choicecommands and a read-only registerfor pixel data as present in the videomemory. Fig. 27 shows the circuitdiagram of the colour extensioncard, which is of standard eurocardsize.Operation of every memory bankand its associated logic is identicalwith that on the corresponding cir-
cuit section on the main card alreadydescribed in a previous article in thisseries.
Read-only register IC, has a functioncomparable to IC13 on the main card(see Elektor Electronics, November1985. page 71). However. ICI in thepresent circuit reads three _v (sigma)signals from the memory banks, in-stead of the single bit v_ read by IC13on the main card. The same com-parison goes for 1C2 on the extensioncard and IC12 on the main card, butin this case IC12 latches a single databit plus a memory write enable bit(DIS and WRIS, respectively).whereas IC2 latches three bits ofboth types: DINRS DINBS, DINGS,WRRS, WRGS. and WRBS. When-ever one of the write select signals(WRXS) is active (i.e. logic low level),a write action takes place in the
EEFebruary 1986
Table 10.
25 colour memory write configurations
1. .11 : no RMW 12...25 RMW
PIXEL
111111 R MANS
- 1 - 0
2 03 04 0
567
89
0
0
0
0
0
DIN RWRS GWRS BWRS RS GS
X X
BS IR TG IB
x x X
DinR DinG DinB
old
R IG la
X X
new
R G BX X X
0X
XXX
x
Xx
xX
x
0XX
EX.X
X--.X' 0
0 XX
XX
0000
00
0
0
0
000
0
0
0
01
X
XXXX
X
X
Xx
X
0
0
0
0
X
XXX
pX 0
0
00
X
XXX
1011
00
00
00
00
0 XX
0
0 X X0
X00
XX
XX
XX 0
XX
12 1 1 1 1 X x X X X X X X X X X X X
1314
1516
0!XX
1
00
0
0
!x
X
X
XX
X
XX
XX
X
XX
X
XX
XxXX
X
XX
0
XX
X
XX
X
X0
0
X
XX
X
XX
17
18
1920
00
0
0
00
0
0
0
0
0
!X
X
!XXXX
XXXX
0
x X
XXXX
0 XXXX
0
XX X
XXXX 0
0
aa0
XXXX
21
22232425
0
0
0
0
1
0000
00
0
0
0
0000
0
0
XX
00
x
0
X
xX
X0
0
0 00X
XX X
XX
000
0
0
00
Notes:
1. No memory access IRWRS = GWRS = BWRS = 11.2. Light red dot (DIN = RS = 01.3. Quench red dot (DIN = 1).4. Quench red dot IRS = 1).5. Light red and green dots (DIN = RS = GS = 01.6. Quench green dot (DIN = 0; GS = 1).
Light red dot IRS = 01.7. Quench red dot (DIN = 0: RS = 11.
Light green dot IGS = 01.8. Quench green and red dam (DIN = 0; RS = GS = 1).9. Quench green and red dots IDIN = 1; RS - GS = 0).
10. Light blue and red dots IDIN = RS =- BS = 01.11. Quench red dat IDIN = 0; RS = 11.
Light blue dot IBS = 01.12. See 1.13. Light previously quenched red dot ( R = RS = DIN = 0).14. Quench previously fit red dot E R = 11.15. Quench red dot IRS = 11.
16. Quench red dot IDIN = 11.17. Light previously quenched red dot 1 R = RS = DIN = 01.
Quench previously lit green dot ( r G = 11.18. Quench previously fit red and green dots 1 R = G = 11.19. Quench red dot IRS =
Quench previously lit green dot (YG = 1).20. Quench red and green dots (DIN = 11.21. Quench previously fit red dot 1E R = U.
Light previously quenched green dot ( G
Quench previously lit blue dot B = 11.22. Light previously quenched red dot 1: R = 01.
Quench previously lit green and blue dots G = = B = 1).23. Quench red and blue dots IRS = BS = 1).
Quench previously fit green dot ( G =24. Quench green and blue dots (GS = BS --- 1).
Light previously quenthed red dot I R = 01.25. Quench all dots (DIN = 11.
X = don't care= dot off
= dot on
memory bank of the relevant colour.If the corresponding DINX line ishigh at that moment, the coloureddot is quenched, whereas it is lit withDINX low.
It is possible to simultaneously writedata into all three banks, providedthe three enable signals are active.The data bits as written into the threememory banks need not be ident-ical; it is possible to. say, light the redand green dots of a given pixel andquench the blue one to obtain ayellow pixel colour. Table 10 lists 25colour memory write configurations;the first eleven without the RMWmode, the remaining entries withRMW mode switched on.
In the lower left-hand corner ofFig. 27, the local address decodercircuits are visible. They are basi-cally an extension of the main card
address decoder whichdecodes two blocks: XX50...XX5Ffor GDP use. and XX64...XX66 forauxiliary registers; a XX6X signal wasderived from this, called EXT, andput on the extension connector. Inthe present extension. EXT enablesIC3 when an address within theXX6X block is present on the hostaddressbus.Installing wire links K -YO, B-2, C-1,and J-Yl will locate ICI and IC2 atthe same memory addresses as theircounterparts IC12 and IC13 on themain card. This double addressdecoding simplifies the video inter-preter and keeps occupied addressspace to a minimum, as will be evi-dent from the following con-siderations.Writing to address )0(64 on the maincard involves bits DO and D4 for DIS
and WRIS, respectively. Reading thisaddress only involves databit DO forE I. Thus, writing leaves six bitsunused, reading seven bits. Ratherthan reserving two additional ad-dresses for the DIN and v bits on theextension card, the double addressarrangement allows efficient use ofthe remaining databits at xx64. Allbite of this address are used. as sum-marized in the following Table 11:
Table 11.
COLOUR = XX64HEX(WRITE)
b7 b6 b5 b4 b3 b2 bl be
iCCIN
ITiCC
Coea
32 I 2zES 25 Ei
Note that only DIS and WRIS aremain card signals, the remaining five
EEFebruary 1986
Fi a. 28. Twoconnectors and alength of 34 -wayfiat ribbon cableconnectextension andmain card.
Photograph 1.Suggested frontpanel constnzc-lion for thegraphics systemTTL leveloutputs. The left -band 19 -inchpanel holds the I(monochrome).snrc, andSYNC outputsockets, theright -/land panelholds outputs R.G, 8. and I forfull colour appli-cations.
originate from the colour extension.A similar procedure goes forreading address XX64, as summar-ized in Table 12. Note that in this caseonly bit 0 cy, I) is a main card signal,the rest come from ICI on the exten-sion card.
Table 12.
PIXBUF = XX64nEx(READ)
b7x
b6x
b5x
b4x
b3EB
b2 blER
1;01
El,
One might perhaps wonder why thedouble address decoder hardwareon the extension card was not re-placed by a simple, direct connec-tion of signals E , DIN, and WRSbetween main card and extension.The answer is that the extra hard-ware solution effectively avoids thecomplications of additional wiring incase more extension cards areadded.To conclude this paragraph, Table 13sums up all necessary addressdecoding options as available on theextension card.
ConstructionBefore going into constructionaldetails, it must be reiterated that thecolour extension is a threefold copyof the corresponding section on themain card, which emphasizes thefact that due attention must be paidto the construction hints given in part4 of this series. It is again suggestedto follow the procedure of ticking offevery step in the construction pro-cess only after the necessary func-tional checks have provedsatisfactory (Table 14). To operate theextension card, a properly function-ing main card should be available,plus a power supply which is able tocope with the additional currentconsumption of the extension.In the suggested step by step pro-
cedure, the memory banks are fittedand tested one after another. Withtwo memory banks fitted on the ex-tension and one on the main card, astandard RGB system is available foruse. The fourth memory bank is in-stalled if a monitor with intensitymodulation input is available. Itshould be noted, again, that all banksare identical and therefore fully in-terchangeable. It was only by con-vention that they were given thenames R, G, B and I in that order, andthe user is free to decide on his ownconfiguration.
CableconnectionConnection of extension card andmain card is not effected via themicroprocessor bus. but via a shortlength of 34 -way flat ribbon cable ter-minated in connector K1, as shown inthe photograph on page 49. Fig-ure 28 further shows how the 34 -waysockets are fitted to the ribbon cable.On the extension PCB, 111 is fitted onthe PCB soldering side to ensure theshortest possible cable between ex-tension and main card. Earth isdeliberately connected at the maincard side only.
ComponentsAs a general rule, the remarks asgiven for the construction of themain card (see pan 5) are also rel-evant to the present extension. As forthe choice of dynamic RAMs, it issuggested to consult Table 9 in pan4 to find usable types. As with themain card, it is best not to use ICsockets; instead, solder all RAMsdirect onto the PCB. ResistorsRa... R31 are preferably fitted as8 -resistor networks, but this is not
Table 13.
links address lines decoded
addressA3 A2 Al A0
0- 2 A2 - E3 0 1 0 0 4C - 1 A3 -C2 0 1 5
1 0 61 1 7
B - 1 A3 - E3 1 0 0 0 8C - 2 A2 E2 0 1 9
1 0 A1 1 B
A - 1;B - 3 A3 -E3 0 0 0 0 0C- 2 A2 E-2 0 1 1
1 0 21 1 3
A - 1;C - 3 A3 -r2 1 1 0 0 CB -2 A2 - E3 0 1 D1 0 E
1 1 F
obligatory. The problem with supplydecoupling capacitors C3. . .C26 isthe same as with that of the ones fit-ted on the main card; they are to besoldered direct onto the IC pins 8and 16 at the PCB soldering side, andtheir earth leads must be as short aspossible.It is a rather delicate matter to fit RASseries resistors R36...1(43 and theirassociated wires to the RAS inputs ofthe next two memory banks. Compo-nent mounting plan Fig. 31b showsthat these resistors have track con-nections to pins 4 of IC31...IC3e , andwire connections from there to theother two memory banks. The wiresare connected direct to the resistorleads, preferably using a wire wrapdevice, before carefully joining wireend and lead with solder. The re-sistor leads are then bent andsoldered into place. The connectingpieces of wire are straightened andconnected to eight soldering pins atpins 4 of the relevant ICs in the nextmemory bank (IC23...1C30). Fromthere, another eight lengths of wireare run towards the last pin 4 con-nections (IC15. . .IC22), which also re-quire soldering pins (Fig. 29). Thesesixteen (8 x 2) pieces of wire ought tobe fitted with the utmost care andprecision to avoid short circuits andresultant malfunction of the card.
Wire linksPoints A... K, see Fig. 27, must be fit-ted as wire links or jumpers on theextension PCB according to thestraight lines in the circuit diagram.The dotted lines represent the linksas required for a second or third ex-tension card.Link L or M is fitted to suit the RGBmonitor bandwidth. In the third partof this series (Elektor Electronics,
121 EEFebruary 1986
November 1985), Fig. 17 showed howthe video output buffers were gatedwith HCK (system clock) to improveenergy distribution between adja-cent and isolated lighted dots. Thesame arrangement is used for outputgates N17...N19 on the colour exten-sion card when link L is fitted. Thisresults in a better defined picture onlow -quality monitors, but has the dis-advantage of doubling the videobandwidth. Now that colour and in-tensity modulation have beenadded, it would seem desirable tomake HCK gate control optional;when link M is fitted, the gates willfunction as output buffers to thepreceding shift registers. Total videobandwidth is reduced to 6...7 MHzwith link M installed, whereas withlink L the full 12...14 MHz band-width of the GDP is present at theoutputs. To choose between the L orM option, simply try out the effect ofboth on the available monitor.As the reduced bandwidth optionwas not foreseen on the main card, itwill have to be slightly modified forthis purpose. Cut off pin 12 of IC26 onthe main card, but leave a sufficientpin length to solder a small wireclose to the IC body. Connect theother wire end to pin 7 of the IC.Note that link M and the modificationwith IC26 must only be fitted if a
improvement in picturequality is thus obtained. The normalconfiguration, however. remains linkL.
The outputsThe VIDI and CSYNC (or CSYNC)signals are available at main card out-put connector K2, but they also ap-pear on the extension . card forefficient combination with VIDR,VIDG, and VIDB into a single 6 -waycable for connection to the RGB(I)monitor. As these are all TTL levelsignals, a common type of cable maybe used, provided it is not too long.A practical suggestion for outputsignal connection is shown in Photo-graph 1; the extension card has beenequipped with a front panel to hold anumber of inexpensive phonosockets. It is also possible to use a 5 -or 6 -way DIN socket, or an 8 -pin EIAvideo socket (Fig. 32). However,these last two socket types lack acertain flexibility as compared to thesimple and robust phono type,which enables the user to easily in-terchange the R, G, B, and I signalsfor colour effect experiments.If a SCART compatible monitor isused, it is necessary to use theSCART adapter, as featured inElektorElectronics, September 1985,page 9-52.
CapacitorsAs already noted, most capacitorsare to be fitted onto the PCB trackside, as close as possible to thesupply voltage pins of all dynamicRAMs. This mounting method isessential, considering the systemclock speed of 12 or 14 MHz. As forthe shift registers (IC12, IC13, IC14), ithas been found that they also greatlybenefit from the addition of 100 nFsupply decoupling capacitors. Forthis purpose, use miniature ceramiccapacitors. With this decoupling, im-peccable video signals are obtained,whilst digital spikes on the powersupply lines are reduced to aminimum.
Colour combi-nations summaryAll possible combinations of basiccolours red (R), green (G), and blue(B) are listed in Table 15, togetherwith the intensity (I) bit, whichspecifies colour saturation. Note thatR, G, and B are in negative logic, theintensity bit in positive logic.
Table 15.
a G R cafe colour
0 0 0 0 off white0 0 1 1 pale purp4e0 1 0' 2 pate magenta0 1 1 3 dark bble1 0 0 4 amber-marnge-,1 0 1 5 dark green
1 0 6 dark red1 1 1 7 bta6x
1 0 0 0 8 bright Yrtate1 a a 1 9 bright purple
8 1 0 10 bright rriager,30 1 1 11 bright b., --x-,1
1 1 0 0 12 bright ye' ..,
1 0 1 13 bright grc,11 1 1 0 14 bright fe,::1 1 1 1 15 cWk gra,
Note that if the intensity bit were alsoactive -low, colours 0...7 would be-come 8...15 and vice versa.As the video interpreter fully sup-ports colour, it is neccessary to es-tablish the order of memory banks inrelation to the primary colour each ofthem is to obtain. To obtain thecolours as listed in Table 15, the fol-lowing convention is used: plane Ion the main card becomes plane R;extension card plane R becomesplane G; extension card plane Gbecomes plane B; and, finally. exten-sion card plane B becomes plane I, ifrequired.
111 1C2E3
0i7.420,
1C36
)114'041'..4151111:11-4'01116 * 0
. . . . ..
Itt'st*it*It'"711 )1
3:
1!)))))..40,041911taak ,t;m- ..r7- :).-t..S7f,i,,,
Yel/MDq-.0- !lint:KA _
1)t.
illirt1. 0
Fig. 29. Thephotograph anddrawing showhow RASresistorsR36...Rt3 and as-sociated signaldistribution wiresare best fittedonto the PCB.Watch out forany short circuitsat pins 8 and 9 ofIC31. .caused by theresistor leads.
29
-,---.1
30
*wen from PCISuAddrine side
LPEN
EXT
RMWS
CSYNC
ViRX
RASE
RASA
RAS2
RAS3
A3
AS
A2
AlCAS
HCX
*K1
1030507090
110130150170190210230250270290310330
020406OaOto012014016018020022024026026030032034
VIDI
/AMEXOINX
LO
SH/L
R AS7
RAS5
RASO
RAS1
A7
Ad
AS
AS
Vi141
85140-30
Fig. 30. Pinassignment ofconnector Ki isof course ident-ical svith the cor-responding maincard connector,but here it isseen from thePCB solderingside.
EEFebruary 1986
54
Fig_ 31a.Soldering side ofthe colourextension PCB_
Fig. 31b. Compo-nent mountingplan for thecolour extensioncard.
Parts list
Resistors: (1/8 W)
RV:An =1kR2 - . . R7 = 22.4
Rm...R.ii= 1004R32- - .R34 =470Q
Note: RS -..R15;R16..- R23; R74 - - -R31 may
be 8 -resistor networks.
Capacitors:
CI =101,;16V tantalumCz =47p;16V tantalum
(fit between connectorpins lac and 4ac; a tolac).
C3 ...Cm= 100n (useminiature ceramictypes, fit capacitorsdirect onto pins 8 and16 of dynamic RAMs).
Semiconductors:
IC, =7415173ICz=741S174IC3=74LS138ICs_ ..ICs=74LS321C7 =74LS08
ICs =74LS33ICI._ _ICII=74LS30IC12._ .1C14=741S166
1C15...1Cie =4168
Note: every make ofdynamic RAM havingan access time of nomore than 150 ns willwork, except for the fol-lowing types:MCM6664 (Motorola)HYB4164 (Siemens)
EFE665 (Thomson)
F4164 (Fairchild)
TMS4164 (Texas In-struments)IM52600 (INMOS)Miscellaneous:
Kt= test socket; doublerow 17 -way; matrix2.54 for mating withribbon cable plug(Minicon Latch PI17w).
test socket; double row8 -way; matrix 2.54 mmfor jumpers (MiniconLatch PI 8w)
6 jumpers (short-circuitplugs for abovesocket).
1 card connector,
64 -way a and c rowsto D1N41612.
5cm length of 34 -wayflat ribbon cable.
2 female 2 x 17 -wayplugs for flat ribboncable.
PCB 85080-2
1100x 160 mml
EE
February 1986
Table 14.
tick ICs action(s)
none carefully check the empty board visually and electricallynone mount completed front panelnone fit 64 -way connector, wire links A.. -K, soldering pins for RGB, VIDI, and LPENnone fit link L/M, connector K1 (soldering side!), wire link between IC2, and IC37none fit resistors R36... R43none fit capacitor C2 between pins la/c and 4a/c of the 64 -way connector, a terminal to laicnone fit R39 two soldering pins ± wires (see text)
E none fit R33 two soldering pins , wires (see text)none fit R37 -
fit R43 two soldering pins ÷ wires (see text)none check Ras... R43 with an ohmmeterICI, IC2, IC3 plug extension and main card onto the bus; connect Ki cable; check supply voltage and
address decoder; writing data to XX64 must cause logic output changes at the IC2 outputsICs...1Cia (÷C1) check presence of signals SH/L, HCK, RAS, CAS. Presence of the extension may in no
way disturb proper operation of the main card1C15...IC22 fit capacitors C3...C10 direct onto IC supply pins at PCB soldering side. Check supply
voltage and current consumption. Connect main card VIDI output to RGB monitor Rinput and extension card output R to RGB monitor G input. Earth monitor B input.
XX64 : 00XX66 : 00 (01, 02, or 03 for turning the page)XX51 : 03XX50 : OC (screen becomes yellow (red ÷ green)XX64 : 01XX50 OC screen becomes green (DIS = 1; DINRS = 0)XX64 : 02XX50 : OC screen becomes red (DIS = 0; DINRS = 1)XX64 : 03XX50 : CC screen becomes black (DIS = DINRS = 1)
1C23...IC3o fit capacitors Cii...Cia direct onto IC supply pins at PCB soldering side. Check supplyvoltage and current consumption. Follow write procedure as above with subsequentbytes 00...07 at XX64, after having connected outputs VIDI, VIDR, and VIDG to monitorRGB inputs. With each write instruction, the screen colour must change as indicated inTable 15.
IC31...1C4o fit capacitors Cle...C26 as with the preceding memory banks. Connect VIDB to B inputof monitor. Follow write procedure as above with successive bytes 00...OF at XX64. Ifnecessary, add 100 nF supply decoupling capacitors to supply pins of IC12...1C14 and ICa.
Fig 31c. Compo-nent side of thethrough -platedcolour extensionPCB.
32EIA video co n ne:tor
(
0
Pin designation
r. Intcnc[y
2. Rod
3. Green
4. Blue
5. Esirsh (RGal
6. E4rth (sync]
7. Compositt syncor horrsontal sync (HSI
B. Vortical sync 1VSI
--.
- NFOCARDSOver recent years the Infocards published in Elektor Electronics have becomean essential part of the magazine to many readers. Each card is crammed full ofvaluable information on topics related to electronics and ranging from copperwire to interference suppression and from resistor colour coding tomicroprocessor ICs. Following numerous requests for reprints, we have madeavailable the set of Infocards 1 to 99. complete with two index cards to simplifylocating any card or subject. Get them now and have a mine of information atyour fingertips.
N; The Infocards are supplied in a handsome plastic case and cost £3.50 + 55p P&P.please use the U.K. (£1.10 outside U.K.)Order Card in this issu
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EEFebruary 1986
THE FUTURE FORARTICIFAL INTELLIGENCE
by Professor Margaret A. Boden, MA(Cantab), PhD(Havard), FBA
Despite its short history, ar-tificial intelligencealready promises tochange everyday life asmuch as the Industrial Rev-olution did.Machine intelligence wasforeseen in the 19th cen-tury by Charles Babbage,whose cogs -and -gearscalculating machineworked in a way basicallysimilar to today's com-puters. A century later,Alan Turing provided atheory about what ques-tions could in principle beanswered by such amachine. Artificial intelli-gence grew out of thework on digital computersin World War II, and wasgiven the dignity of aname in 1956.Since the early efforts inthe mid -1950s, it has hadsome notable successes.Today's computers canperform some of the tasksnormally done only by ourminds - though only to avery limited degree. For in-stance, some programscan respond sensibly toqueries or statements ex-pressed in naturallanguages such asGerman or English -which means that or-dinary people do notneed to learn a specialprogramming languagebefore they can interactwith them.
Expert systemsConversations with most ofthese programs have totake place over ateletype, but some canrecognize spoken words.Other programs can de-scribe the shape and pos-ition of visible objects, andidentify what they are. Stillothers can play games, orcomment on events from aparticular political stand-point. And some can solve
problems of various kinds,like those which an in-telligent robot would haveto tackle.The most publicly visibleapplications so far are theprograms called expertsystems. Some are alreadybeing used experimentallyto give advice on medicaldiagnosis and prescrip-tion, genetic engineering,chemical analysis, andgeological prospecting forminerals and oil. Futureexpert systems will beused by ordinary familiesfor example, to helpmotorists diagnose and fixfaults in their cars.An expert system has builtinto it some of thetheoretical knowledgeand rules of thumb usedby human experts. And itcan be improved, up to apoint, by adding new in-formation. So that it canhelp on a particular prob-lem, it is given theevidence that its humanuser has - it can suggestthat relevant tests be done,if they have not beendone already. Then it sup-plies an opinion based onthis evidence. To make iteasier for people to evalu-ate its advice, the expertsystem can display itschain of reasoning.Current expert systems arevery limited in what theycan do, however, largelybecause they cannotreason about their ownreasoning, or the user'sreasoning either. Theycannot explain their con-clusions differently to dif-ferent people, since theyhave no user -model interms of which to adjusttheir explanations to aperson's level ofknowlegde. But despitetheir limitations, a few cur-rent systems give morereliable advice than allbut the very best humanexperts, and one or two
surpass us all. The worldexpert on soya beandiseases, for example, isnot a person but aprogram.
Long termfundingGovernment money fromthe western industrializednations is being pouredinto artificial intelligenceresearch, in bothacademic and industrialcontexts. The EuropeanCommunity has estab-lished the ESPRIT projectfor funding co-operationbetween its membercountries in research intomicro -electronics and soft-ware technology. The firstphase of ESPRIT will drawon £465 million from Com-munity revenues.The British Government, aswell as having a stake inESPRIT, has set up thenational Alvey Committeeto recommed a strategyfor the long term fundingof artificial intelligenceand related computa-tional techniques. Govern-ment funds of £215 millionhave been allocated forthis information technologywork.The electronics industry istaking this researchseriously too, matchingESPRIT's £465 million withan equal contribution.And the Government's £215million is also equalled byindustrial money set asidefor the Alvey research anddevelopment projects.What are these machinesof the Future, the so-calledfifth generation com-puters? The first four gener-ations are defined inhardware terms: machinesbased on valves, tran-sistors, silicon chips, andvery large scale inte-gration (VLSI). The
predicted fifth generationis defined in terms notonly of improved -massively parallel - hard-ware, but also of artificialintelligence.
robotsIt is hoped, for instance, toachieve reliable machinetranslation betweenvarious natural languages- even on texts that arenot restricted to highlyspecialist subject matter.And some people forecastthat computers of the1990s will be able to inter-pret the speech of manydifferent individuals, to actas intelligent assistants ina wide variety of tasks,and to provide advancedproblem solving andsensori-motor abilities formobile domestic and in-dustrial robots.However, achieving fifthgeneration computers willbe much more difficultthan most people assume.Once they have acceptedthe fact that some sort ofmachine intelligence maybe possible, most peoplegrossly underestimate thedifficulties involved. One ofthe prime lessons of ar-tificial intelligence is thepreviously unrecognizedrichness and subtlety ofhuman common sense,and the extent to which itguides our thinking. Never-theless, by 1990 thewestern nations will havea wide variety of commer-cially useful applications.It is not inconceivablethen that artificial intelli-gence programs will beused by the generalpublic at home. What ismore, they will be used bymany professionals whosedecisions affect people'spersonal lives. Are there
EEFebruary Ign
dangers in this prospect,and, if so, can they beavoided?The man in the street mayplace too much trust evenin today's limited pro-grams. One might almostsay that it is theunintelligent tasks thatsuch programs cannothandle. Many of the thingsthat our minds enable usto do are not normallycalled intelligent,because we can all dothem so easily.Everyday abilities like talk-ing, seeing, or realizingfriendliness from a facialexpression, do not nor-mally need conscious ef-fort. Nor can we say howwe do them. But they arefar from simple. Indeed,their complexity - andsubtlety - was not ap-preciated until researcherstried to model them oncomputers.The activities that involveour common sense pres-ent a daunting challengeto artificial intelligence. Bycontrast, many of the taskswe pay highly specializedprofessionals to do haveproved more tractable. Ex-pert systems can alreadyadvise us on some of therecondite problems facedby mathematicians, doc-tors, genetic engineers,geologists, and chemists.This seeming paradox hassurprised researchers, andmost members of thepublic still are not awareof it. The widespread ig-norance of this fact canbe dangerous, to somedegree, for it means thatmost people lack areliable sense of whichquestions current artificialintelligence systems canbe expected to handle.It will be difficult to warnpeople of these dif-ferences as future systemsachieve more humanikeprograms whose limi-tions will not be so readilyapparent to someone in-teracting with them.There is no hope ofdeveloping fifth gener-ation systems unless theycan be made morehuman than today's pro-grams. This will requiresome basic theoreticaladvances.
58
How smart arethey?Tomorrow's computers willneed a better grasp ofnatural language, forexample, and a better ap-proximation to commonsense thinking. Withoutnatural language theywould be useless to theman in the street, whodoes not want to learn aspecial programminglanguage, and they wouldbe unable to interpret writ-ten texts or reasonablynormal conversation. Andwithout something likecommon sense, theywould fall into all mannerof absurdities.A future expert systemcould appear to have afairly subtle command ofnatural language withinthe subject for which itwas designed. Many usersmight therefore assumethat it has a completecommand of thatlanguage, at least in thatsubject. Some might evenbelieve it to have a richcommand of language inother areas too. Thesefalse assumptions couldlead to its judgments be-ing given more credit thanthey are worth.Suppose the computeruses a familiar Englishword such as possible. Theuser knows that this word issimilar in meaning to anumber of others (such asprobable, likely, con-ceivable, and so on), butalso knows that it is notprecisely equivalent toany of those, for eachword has subtly differentshades of meaning.Therefore, we should notassume that the wordsused by the computer,however well chosen incontext they appear to be,have been carefullyselected in preferance toother words carryingrather different im-plications.What of common sense?This is needed, forexample, when someonehas to make guessesabout relevant facts. If oneof these guesses is incor-rect, that new informationcan be used from then on.
People can cope with thefact that a statementjustifiably assumed to betrue at one time can laterbe found to be false.
UnderstandinglimitationsThis cannot happen in tra-ditional logic, whereintruths are proved onceand for all. And traditionalartificial intelligence pro-grams are based on thistype of logic. Conse-quently, much research atpresent is trying to for-malize non -monotonicreasoning, in which truthvalues can shift from timeto time as relevant infor-mation reaches thesystem.The limitations of artificialintelligence programs aswell as their potential mustbe understood. In par-ticular, it must be realizedthat every program can inprinciple be questioned.The reason for this may besurprising. Programs arenot objective systems thatguarantee the truth, butrather subjective ones thatrepresent the world inways that may or may notbe wholly veridical orreliable.An artificial intelligenceprogram uses somerepresentation of data,which may be partiallyfalse andor incomplete. Ituses rules of inference,which may be faulty invarious ways - many willbe hunches that are sen-sible only in certain cir-cumstances. And itemploys decision criteria,or values, to select onecourse of action ratherthan another and theseare essentially prob-lematic. The crucial point,then, is that a program'sdata, inferences, andvalues can always in prin-ciple be challenged, justas they can when contain-ed in a human mind.
Teaching workSome work has alreadybeen done on developingteaching systems capable
of encouraging this sort ofcomputer literacy. One isthe POPLOG systemdeveloped at the Univer-sity of Sussex over the pastten years for teaching artsand humanities studentsthe principles of artificialintelligence programming.It is a user-friendly, interac-tive programming environ-ment, with a large libraryof "teach" and "help" filesthat enables students tolearn at their own speedand in their own way. It is
also a powerful researchtool, since it allows theuser to write programs inLISP, PROLOG, and POP -II. Ithas been recommendedby Britain's centralresearch councils as amain tool for current ar-tificial intelligenceresearch.A system like this can beused to show studentsfairly quickly that an ap-parently intelligentprogram is neither so in-telligent as it seems, norunalterable. For PROLOGhelps the student to ex-plore and alter mini -versions of programs.Take ELIZA, for example, arelatively simple programthat interacts with its userby way of Englishsentences. If you type intoELIZA the sentence Myfather drove me here, theprogram will answer: Tellme more about your fam-ily, or perhaps: How doyou /eel about yourfather? If you type in: /mistrust you, ELIZAresponds with: Why do youmistrust me? This seemseerily humanlike. But if youwere to type in: /bIggIskxzyou, ELIZA will just as hap-pily ask: Why do youblgg/skxz me? In short, theprogram has no under-standing of English. It con-sists merely of a few simplerules of recognizing a fewspecific patterns orkeywords and respondingblindly to them instereotype ways.
Social im-plicationsNo one knows what the ef-fects of artificial intelli-
gence will be on our dailylife in the future. Even thelong term influence onunemployment is unclear.Some economists see apost-industrial societybased on informationtechnology, in which onlya few people at oppositeends of the educationalspectrum have jobs as weunderstand the term to-day, while others forecasta return to full employ-ment after the transitionstage.All agree, however, thatthe pattern of employmentwill change, and thesechanges could lead to amore humane society.Many jobs will beavailable in the service
and caring sectors of theeconomy: education,welfare and health care,entertainment, sport, andcraft activities.These ways of spendingone's time are intrinsicallymore meaningful andsatisfying than many -perhaps most - jobs in in-dustrial societies today.Moreover, even with fullemployment, workinghours will probably be re-duced. So people willhave more time to spendwith their families andtheir friends than they donow.Finally, what of the threatthat artificial intelligencemust deny our individu-ality and freedom? Many
people fear thisdehumanizing influence ofcomputer technology.They would be right to doso if it were true that ar-tificial intelligence canallow no room for theseaspects of humanpsychology. It is not.Artificial intelligence doesnot lead to a reductionistpsychology - such asbehaviourism was, forexample. Indeed, it islargely due to the in-fluence of computerbased ideas thattheoretical psychologynow takes the mind, andmental representations orideas, seriously again.Moreover, research in ar-tificial intelligence en -
SE
February 1986
courages a new respectfor the richness and powerof everyday human men-tal processes. Artificial in-telligence can counteractthe subtly dehumanizinginfluence of the naturalsciences, in which there isno room for concepts likebelief, reason, inference,purpose, and choice.
59
THE ACCORDIONIMAGE SENSOR
Scientists at the Philips Research Laboratories have made anew type of solid-state image sensor: The new sensor hastwice as many fight -sensitive elements per unit area as
previous sensors. This has been achieved without the needof a finer pattern for the electrodes applied to the sensorsurface by IC technologies. The improvement is achievedby a new method of distributing the potentials over the
electrodes. In this method a row of picture elements (pixels)is located under every two electrodes, whereas four
electrodes were previously required for each row. Theavailability of only two electrodes per picture elementmakes the transfer of the image information from the
camera' section to the 'memory' section (frame transfer'rather more complicated The potential hills that separate
the information coming from the different individualelements are now stretched out one by one and then
compressed again, like the bellows of an accordion.In a solid-state imagesensor, and also in a CCD(charge -coupled device)shift register, narrow paral-lel channels of n -typematerial are located in alayer of p -type silicon. Onthe surface there are lin-ear electrodes, which areperpendicular to thesechannels. The electrodes
are insulated from eachother and from the siliconsurface. If the silicon sur-face is exposed to light -through the electrodes -electrons are released inthe silicon. If suitablepotentials are applied tothe electrodes (Fig. la),these electrons will buildup charge packets under
the positive electrodes inthe n channels. In this way,charge is collected duringa scanning period, withthe size of the chargepackets providing ameasure of the local il-luminance in the image.Next, during the read-outphase, the electrodepotentials are varied in
such a way that thepotential hills and valleysexecute a 'peristaltic'motion (Fig. lb), whichtransfers the chargepackets from the imagesection to a storage sec-tion. From there they areread out line by line so asto supply the video signal.During the following scan-
EE
February 1986
ning period, the potentialpattern on the electrodesin the image section isshifted by two electrodewidths to give the usualtelevision interlacing.Although three electrodesper cell would be suf-ficient for transfer of thecollected charge, fourelectrodes per cell aregenerally used, as indi-cated in Fig. 1. This pro-vides simpler control andcorrect interlacing.If the conventional 3.5 -gmtechnology is used inmaking a sensor, the celldimensions will be fairlylarge. They can be madea little smaller by using athree -layer electrode struc-ture. If this is done, how-ever, the light incident onthe sensor at some placesmust pass through threelayers of electrodematerial (polysilicon)before it is detected. Thisgives a reduced sensitivity,particularly in the bluepart of the spectrum.
60
The accordionprincipleTwo electrodes per cellare in principle sufficientfor collecting the charge.With this arrangement,however, charge transfer isnot as simple as before, sothe following techniquehas been devised. Insteadof transferring all of theimage information to thestorage section at thesame time, each chargepacket is temporarilyspread out in the spacebeneath two electrodes,and separated by apotential barrier two elec-trodes wide, beginning atthe bottom edge of theimage section. The con-ventional method ofcharge transfer can thenbe used, and the imageinformation is 'peeled off'line by line. The temporary'stretching out' of the infor-mation disappears againwhen the charge packetsreach the bottom edge ofthe storage section, sothat in the storage sectiona row of picture elementsagain comes beneath twoelectrodes. All this is
shown schematically inFig. 2. As the final read-outproceeds line by line atthe bottom edge of thestorage section, it auto-matically creates thespace required for therenewed stretching out ofthe charge packets beforethey are transferred to thebottom edge.In this way much smallercell dimensions can beachieved with the same
production method, the3.5 -gm technology: a totalof 604x588 light-sensitiveelements can be locatedon a area of 38.2 mm2.With this method, it is alsopossible to reduce thearea of overlap betweenthe electrodes con-siderably. If the width ofthe electrodes is also re-duced locally, the sensi-tivity is improved, particu-larly in the blue region.
Fig. 1. a)At the top is aschematic cross-section ofthe electrode structure of asolid-state image sensor, inthe longitudinal directionthrough an n -type siliconchannel. One cell coversfour electrode widths.Below the cross-section, thepotential distribution duringthe recording of a pictureis shown. The chargepackets in the potentialwells are indicatedschematically.b) Sequence of potentialdistributions for transferr-ing the image information(to the right).
Fig. 2. Schematic represen-tation of the potentialdistribution in an accordionimage sensor at successivemoments during the trans-fer of the image infor-mation from the imagesection to the storage sec-tion. At top left the first in-formation leaves the imagesection. The pictureelements that initially covertwo electrode widths arestretched out one by oneover four electrodes: theaccordion is 'pulled open:At bottom right the first in-formation arrives at the farend of the storage section.The information for one im-age point is once again ac-commodated in a storageelement two electrodeswide: the accordion issqeezeol shut again.
Fig. 3. The accordion im-age sensor. The image sec-tion (dark) and the storagesection (light) are at thecentre. The electronic cir-cuitry for generating theelectrode voltages is shownalong the edges. Insetenlarged view at the transi-tion from image section tostorage section.
Fig. 3 shows the completeimage sensor describedhere, with part of the pic-ture enlarged.The results described hererefer purely to laboratoryresearch; they in no wayimply the manufacturingor marketing of newproducts.
61 EE
February 1986
This month we feature some fantastic bargains. Our standardrange of professional quality kits and cassette decks is still eapanding Mono with new Ones in Video heads and power stro-phes Our FREE list ernes details of these and many other linesAs t BARGAIN tertts IN THIS b THE NEXT COLUMN INCLUDEVAT 0 POST
MODEM OPTICAL ISOLATOR UNITS=lay Unhat 1.61CO3 oPtCal eseiatca rani. deSared to trorde ..tteeert
between 4sta Ittrrit-MY t,CAPPiN{ K9617,Xitrt3 FWP iSaration up io 2.20r moth a nal foot speed of 953) Baud.Cernoiete urn as 4:.. high, 97i- wide. 7- deep ad ne,ia's 5':8s.POPN SM.', d 2O3. SOI.It 7114-7,IS_ tined .v=:..0.. ca-M-.7-,CrS for RSZ-ZZOUR PRICE ONLY
LIQUID CRYSTAL DISPLAYWATCH MODULE
11995
'....th LCD das0..r, 2 retts of P1Xer:sr.7 materid. tack -loft Oft.rsetr,.cro Urna pretheian crystal trim-, Pat-terr coma.-ta and CpEr.rrcrocirevt. Untested 5 for El
PLESSEY MAINS INTERFERENCESUPPRESSORS
;,..-_,,, ..... for mans tome r,..te Man oaten: 1.54 Our Prattt -s -ti roe. [We a 27
El 61
10 W POWER AMPLIFIER MODULE
23rrn Complete wide heat i T 'I
ALPS FF317U FM FRONT ENDEt..r.:0 ..7,7,--.0c, r....7-2 hsn Or_..t,ty ',i.e.,. ^co FMFiord Ertl with Ekelonte MosRt.=,..-:r, La Fte range of 87 to 4L9 Melr 12. sappe.ONLY £5.15 Caton d re:1,...,1 :ii -c -
CAR RADIO FM IF AND STEREODECODER
WI -anise PCB Wan le 75114z operm: !hem 2 trawst.oww ratio &lec-tor. AVM nose suocresaon IC and TC..-Wc03A advanced Sewer>dock*, IC One, reeds horn end to rraao FM tuner or can radio Con-de -It with omit.Incredible value at Only E1.99
SLIMLINE AXIAL FANSCrowe: grtC60-, rr-sYSe 93rrim Square and any 25erm MotLena. USa Fryer Type V93. Z.B.0 RPM 11-5v b3tLe 531.7. quid n cot,aron and ic4a tor fetal pees flermeh these cost a o-^ELS eachOUR PRICE ONLY ES 48
CLOCK/TIMER/FREQUENCYMETER PARTS
totter tad litouerxymeter 0-4,. MSL1313 presoalw hp a -n 6303 5Dga fearrostent drspte, 3 c.-n..ay thrrepOrentS fora complete trrthgard Ere
E::. c...wsrq rte Wag. media:1.n. short and FMt s thdie pats 6 ncrrraer ode f25_
OUR .. -==ER PRICE ONLY 111611IfiFZI: - - ' ' . ' t -rd T7SL2313 70p!line) A 20pChslal 3:- a la
COMPLETE STEREO TUNER MODULE3 Band. LWIMMFM Stereo Toner fuer assemod on PCB t53-Eromm Su wth Forte Rod Aen.B. Utrea LED and bard sv,--1fall vexed_ 1.2e DC Sappy.111-40 Turktf. Pete - . Only £7.99Dr's ay.:than-0n with 2 knobs. tu,ng arum. wrote. and scat. a 99Special price psi bath den Lan -tit togtst.r M 70
Personal callers are always very welcome but pleasenote that we are closed all day Saturday
HIGH QUALITY REPLACEMENTCASSETTE HEADS
_ .
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Do ye., ..rr, jot, - - te tre pictlem Petteytoe of our r55h- - - _ --'n-mece to Lear thul
helps so, set the atrr,r, s;..ot-tn. We are are actual istithnears you get the bereft of ktn,t, y446 for Were Peed- [unclewith other -.min. and see' The reboring is a Col of ors -most popufarreads, al de satiV for use on DON dourest and ore es -stockHC23 PerrnalSay Stereo Head. This as the stardaro 1"*.id fared asOrKir.t torprient on mast decks £5.31HM93 High Beta PerrnaRoy Head. A turd-nse-ri pcdorrra-ice read with molest capab7er 03E6HS16 &enthral Alloy Super Head. The test head we can fr.:Lt.-2dtie than Permafor, higher outaut than Ferree. fantadic frequencytestcnte 0.91H 0551 4.Treek Head fce auto -reverse cr cpsadroceicinc use. RA .5.0-f:i.e.:, rooted and ptvrtedr ........ . . . 151.73
Pease costa`, P.r tu for tart -erica dna anthem and ether Spe,..:4 Ra-pe. His.MALSI Latest version Double Mono On/ Record 'Play head.
M 93551166 Standard Mounting 2/2 Erase head. COmPattin Win
h 0561 A T,- 5931.1524 Standard Erase Heed. Son: ora..tee oaa. hich effirency E1.50H561 lilenJ Tape Erase Head. Fidi £4 .90
HART TRIPLE -PURPOSE TESTCASSETTE TC1
One ketoeris..e red cassette e-atYes you to set up VU ter. IA readarirtuth and tape speed Imakatre weal fangmisleads Deer E4.66can VAT and ad ooraot
Tape Head De -magnetiser. Handy sire .are; comsted unitP-rkl up of rr.r.e in head 11-.Kint{SMMI ca.r.ng none on
Et StCaned Pole ;Yoe for inaccesbie read E495
sand fa, poor bee Alm ar UST'S_ cA-.Lre IRCsrow, r,faze Pota o, 5 IRCs for AernalPeaoc S.t7 part n2 sr Of P751. P.KliV a -Yd 5213,V-Ct M /0."1.5 -
INLANDEa-ders. tro ,S 510 - sobCeders ITO to Et9 - Eladers c.=_, - El R.'
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0)
EE
February 198662
1- -
CARBURGLARALARM
Although no alarm offers complete protection againsttheft, it will, none the less, deter most thieves andjoyriders The alarm described here, once set, can onlybe disabled by a four -digit code; even cutting its supplycables will set it off.
The alarm may be triggered by thedoor contacts for the courtesy light.an infra -red sensor. a vibration detec-tor, or an ultrasonic sensor. In ad-dition, the circuit reacts to any smallvoltage drop across the car battery,for instance, when the courtesy lightcomes on.Even if the thief discovers thewhereabouts of the alarm andsmugly cuts the supply cable to it, hehas gained nothing, for not only hasthe alarm already been triggered,but also the ignition circuit has beenbroken. There are only two ways ofdeactivating the alarm: typing in thecorrect four -digit code on a smallkeyboard within 15 seconds from
opening the door, or disabling thecar. The latter is obviously not the in-tention of the intruder.The block schematic in Fig. 1 showsthat the alarm can be set off by avoltage drop across the battery or bya pair of contacts that are controlledby the sensor. Once you have turnedoff the engine and set the alarm, youhave fifteen seconds to leave the carand shut the door. A red LED in-dicates that the alarm is live.When you return to the car and openthe door, you have fifteen seconds todisable the alarm. Failing that, theamplified alarm pulse is applied tomonostable MMVI. This immediatelysets off a buzzer (pre -alarm), while fif-
teen seconds later another oscillator,MMV2, is triggered, which causesthe horn to be sounded uninter-ruptedly for thirty seconds. At thesame time, a second relay breaks theignition circuit, or, in the case ofdiesel engines, disables the startingrelay. After thirty seconds, the alarmresets itself automatically, so thatafter another fifteen seconds thehorn sounds again for thirty seconds.
Circuit descriptionThe alarm is actuated from anumerical keyboard as shown in
63 EEFebruary 1986
Fig. 2. Five of the keys are connectedto a data processor, IC7, which con-trols the circuit. As soon as pin 1 ofIC7 is enabled by the logic 1 causedby the pressing of the ON key, datainputs II to I4 are active. In addition,output LIO - pin 8 - goes high. sothat Ds lights to indicate that thealarm is set.The individual code for each user isestablished by wiring the data inputsto the chosen key contacts. Note thatthe first digit of the code numbermust be wired to II, the second digitto 12, and so on.Any voltage peaks on the supply lineare suppressed effectively by regu-lator ICa. This IC is internally pro-tected against incorrect polarity andoverheating, and is provided with acurrent limiter. Moreover, it causes avoltage drop of only 0.4 V acrossitself, which is advantageous in bat-tery operation.The output voltage of the regulator is8.5 V, so that its input voltage can bearound 9.5 V. Capacitor C2 sup-presses any voltage peaks occurringwhen the engine is being started.To minimize the current consump-tion, only IC3, IC6 , and IC7 are pow-ered during quiescent operation: theremainder of the circuit is switchedoff by T2. In the alarm condition, thewhole circuit is energized with theaid of N3, T3 , and T2. The positivesupply line is then about +8 V.A pulse is generated at the switch -onof the supply and this is suppressedby R22 -C15 -N2 -N3 to prevent itreaching the reset input of the twomonostables. If this were not done,pulses might be generated by theseoscillators that could cause the alarmto be set off. In this condition, the cir-cuit draws a current of 15 mA, ex-cluding the relays. The time constantof R22 -C15 is 15 seconds, and this isthe time available between theengine being switched off and thedriver leaving the car.As mentioned before, the alarm mayalso be set off by a small voltagedrop across the battery, such as thatcaused by the courtesy light beingswitched on. This voltage isamplified by AI. The non -invertinginput of this opamp is held at half thesupply voltage by divider Ri-R2. Thevoltage drop across the battery is ap-plied to the non -inverting input aswell (via CI). The gain of At, a, is de-termined by the ratio R4:115 in theformula
a=20logio(l+RaR5) [dB]
Values of R. and Rs as shown give again of 40 dB, but this can, of course,be adapted to individual re-quirements by altering the value ofeither or of both the resistors.
The output of Ai is applied to the in-verting input of A2, which comparesit with the reference voltage at itsnon -inverting input. The referencevoltage - and thus the sensitivity ofthe comparator - can be alteredwith the aid of Pt If the output of Aiis smaller than the reference voltage,the resulting leading edge at the out-put of A2 triggers monostable MMVtIf one of the two monostables hadalready been triggered, the newpulse would be suppressed by144 -D2 -Rio -Ca -Ti. This is effected byprocessing the logic 0 at the Q out-put of MMV1 or MMV2 in a mannerwhich causes Ti to be switched onrapidly via D2. When the output stateof Na changes, Ca slowly dischargesvia Rio until the transistor is switchedoff. The discharge of Ca must beslow, because a fast pulse might setoff the alarm.Assuming, however, that themonostables had not been triggeredpreviously, the pulse at the output ofA2 would cause the oscillator N5 -N6to be switched on and this in turnwould actuate the buzzer, i.e. the pre -alarm. When MMV1 changes stateafter a period determined by thetime constant R12 -C9, the main alarmis set off. This is effected by MMV2being triggered via C11 -126.-N7, whichswitches on oscillator NA. The oscil-lator drives Ts and T6 into conduc-tion, and this results in the horn relaybeing energized and deactivated atregular intervals. When MMV2
changes state after a period deter-mined by the time constant 1114-C10,oscillator NA switches off, and thehorn stops being sounded. At thesame time, the alarm resets itself.If the alarm is triggered by the doorcontacts for the courtesy light, aninfra -red sensor, or similar detector,the circuit functions as describedabove, except that in this case thetrigger pulse is generated by the rel-evant contact being shorted to earth.Monostable MMV2 is then triggereddirect - without pre -alarm - viaC12-Ra-N7.
ConstructionThe alarm is constructed on twoprinted -circuit boards: a small onefor the keyboard and IC7, and theother for the remainder of the circuit.The few components on the codingboard are soldered at the track side.This entails soldering IC7 in anunusual manner. with its pins bentover at the sides, which should, ofcourse, be done very gently.Because of this arrangement, theusual component side of this boardis not shown, but the track side canbe seen in Fig. 3.The key switches are fitted at thecomponent side as shown in Fig. 3.Any superfluous parts of the boardmay then be cut off. Next, the codingshould be wired in. If this is, for in -
Fig. I. Theblockschematicshows the ver-satility of thecar burglaralarm. Evenwhen all thefuses haveblown and thehorn does notwork, the alarmis still effectiveby disablingthe ignitionsystem.
1
ignition
numerical keyboard
8 9
0 ON
T=20s
amplifier detector (sensor)
2 V battery
INH
MMV1
T 15 1
EN
MMV2
T = 30 s
EXT.
larm switch
86005-1
horn
EEFebruary 1986
battery12 V
12 V
QP1
1N4001
500 rnA
.12 if
0r--
oL._ _J
RI
R3
R B IC6L
4885
8V 72BC 327
C2
100I10004 25V
+K
C3
2209 10V
pClIV=mim
6n8400V
220P
8
Al
R4
r -
R17
1 14
EU
wifsRS7
MIL
IC7LS
7220
2
011013
MIL 14-0 0-01.
Al = IC1 = 3130A2 = IC2 = 3140N1 ... N4 = IC3 = 4093N5 ... N8 = IC4 = 4093MMV1,MMV2 = IC5 = 4538
CaL R2
1076V
Fig. 2. The cir-cuit diagram ofthe car burglaralarm.
RS
PI
780n
EXT.0
LCO
110
IC3
13 CO
8191 w
12 V
06
1N4001
ALARM8 ON
05
Jov
72916V 4
73
BC 5478
R21
ignition
0Re2
EOM
T4
BD 139
R12
CII
In
R13
B
R23
7
12
C13
¶30w
11 2
11
2
132
R6
R7
1N4148
R14
R16
R15
MMV2
RS7130
0
9D -
R24
75
12 V
0
07 Re11:1
EM1N
4001
R25
12) Km cr.
C14
BC 5578 R26
2k2
76
BD 139
8600S-2
Parts list
Resistors:
RI:R2:Rr = 10 k
RI;Ra;Rs;Rs;RII;Ris = 100 k
Rs;Rs= 1 kRict;R22;R23:R24= 1 M
R12=560 kRIERIs =470RI/ = 270 k
1117:1321;112s=2k2
Ris =10Ris=4k7132cli2s =47 k
P1=1 M preset
Capacitors:
Cs=6n8;400 V; plasticmetal film
C2= 1000 p;25 VC3 =220 p:10 VC4;CI4= 1 p;16 V
Cs = 10 p;16 V
Cs =220 pC7 = 680 n
Cs= 220 nCs =22 p;16 VCol= 100 p;16 VCII;C12= 1 nCI3 = 330 p
Ci5=47 p;16 VC16=100 n
Semiconductors:
DI:Ds;Dr =1N4001D2;DE04=1N4148Ds = LED;rec1;3 mmTI=BS170T:=BC327TI = BC547B
T4 = BD139
Ts= BC557BTs= BD139
IC1;1C2= CA3130
ICEICs =4093
ICs =4538
ICs = L4885 ISGS)
IC7 = LS7220 ILSI1
Miscellaneous:
ReI;Re2 = automotive
relay 12 V;30 A withmake contact
Bz=piezo electricbuzzer; 6 V
Fl= miniature fuse500 mA;quick- blow;
with suitable carrier11 keyboard switches
with keytops (1 ifpossible with 3 m holefor LED)
PCB 86005-1'PCB 86005-2'
'READERS SERVICESp. 70
C>I FOOC:i;1
ro
c;(71) or 8Orp n
tkoi 11310-
gm r_lja°MO° 440D -1 G
U) AITP c3)A r°
0:TIO 0 Ooo 0 0 0IU o co +8
stance. 2836. key number 2 is con-nected to input I, of IC-. key 8 to 12.and so on. It is sensible to leave off(or rub off) any numbers from theswitches and memorize the codedones (in the right sequence!). Keycontacts not used should all bewired in parallel to pin 2 of IC-. Thesoldering side - which now showsthe coding - should preferably becovered with darkened araldite torender the coding invisible.The LED. De is fitted into the ON key,into the centre of which a 3 mm holeshould therefore be drilled. if thathas not already been provided.This small board should then be fit-ted within easy reach of the driver: ifyou do not smoke, the ashtray is asuitable place.The main board - see Fig. 4 - iseasily wired. Note, however, that tosave space all resistors andcapacitors, except C2, are fittedupright. The relays are not fitted onthe board: these components shouldbe suitable for operation in motorvehicles -a typical pin -out is shownin Fig. 5 - and have a make contact.The contacts of one are connectedbetween the 12 V terminal (SW) ofthe coil and the ignition fuse. andthose of the other in parallel with thehorn switch, but only if one contactof this switch is connected to earth.Where this is not the case, the con-tacts of the second relay should beconnected across terminals 85 and86 of the original horn relay. The newrelay is necessary because theoriginal one cannot cope with thesustained current when the alarm isset off.The main board should be fitted in asuitable housing and installed neatlyin an out of the way position. Oncethis is done, it can be connected tothe coding unit by a three -corecable. AS:AD
5
.1MIIMP
O C 030 86 85 87
86005-5
65 EE
February 1986
Fig 3. Trackside of thecoding PCB Asuitableenclosure maybe solderedonto the cop-per edges ofthe card.
Fig. 4. Printed -circuit boardfor the process-ing section ofthe car burglaralarm.
Fig. 5. Typicalpin -out of therelays requiredfor the controlof the ignitionsystem and thehorn.
EEFebruary 1986
66
£1 BAKERS DOZEN PARCELS: reel is £1.00, but i1 yc *-- ,au get ore
parcels listed below are brand new components-_ - marked s.h.
1- -5 13 amp nng main junction boxes2 -5 13 amp ring main spur boxes3 - 25 13 amp fuses for nng mains4 -5 surface mounting switches suitable insulated for
mains voltage5 -3 flush electrical switches intermediate type. will also
replace I or 2 way switches6 -5 in flex line switches7 -4 in flex fine switches with neons8 -2 80 watt brass cased elements9 -2 mains transformers with 6v la secondaries
10 -2 mains transformers with 12v Sea secondaries11 -1 extension speaker cabinet for 6W speaker12 -5 octal bases for relays or valves13 - I2_g_ _lass reed switches14 -4 OCP 70 photo transistors15 - 25 assorted geranium transistors OCAS etc16 -4 tape heads, 2 record, 2 erase17 -2 ultra sonic transmitters and 2 chno receivers18 -2 15000 mfd computer grade electronics19 -2 light dependent resistors similar ORP1220 -5 dill micro switches21 -2 mains interference suppressors22 -2 25 watt crossover units23 -1 40 watt 3 way crossover unit24 -250 various screws and self tappers25 - 1 of each wafer switches -6p 2 way: 4(3 3 way: 2P 6
way: 1p 12 way26 -2 tape deck counters27 - 1 6 digit counter 12v28 - 1 6 rSgit counter mains voltage29 -1 BOAC in flight stereo unit (second handl30 -2 Nicad battery chargers31 - 1 key switch with key32 -2 humidity switches33 -2 aerosol cans of ICI Dry Lubricant34 - 96 x 1 melee lengths colour -coded connecting wires35 -4 battery operated model motors36 -2 air spaced 2 gang tuning corxlessors37 -2 solid cbaelectric 2 gang tuning condensors38 - 10 compression trimmers39 - Long and Medium wave tuner kit40 -4 e 465 KC IF transformers41 -8 Rocker Smitten 10 amp Mains SPST42 -6 Rocker Switches 10 amp Mains SPOT43 -5 Rocker Switches 10 amp SPOT Centre Off44 -4 Rocker Switches 10 amp DPOT45 - 1 24 hour time switch mars operated (Sel I46 - 1 6 hour clock timeswitch47 -2 lever switches 4 pole changeover up and dam down48 -2 6v operated reed switch relays49 - 10 neon valves - make good night tights50 -2 e 12v DC or 24V AC 4C0 relays51 -1 x 12v 2C 0 very sensitive relay52 -1 x 12v 4C 0 relay53 -2 mains operated relays 3 v 8 amp changeovers
(secondhand)54 - 10 rows of 32 gold plated IC sockets (total 320
sockets)55 - 1 locking mechanism with 2 keys)56 - Miniature Uniseteclor with Ciestuet for electric pgsawpa.e57 -5 Dolls' Hous switches58 -2 telephone hand sets incorporating ear Pece and
mike (sir.)59 -2 fiat solenoids - ideal to make current transformer
etc63 -5 ferrite rods 4' x 916' diameter aerials61 -4 ferrite slab aerials with L & M wave coils62 -4 200 ohm earpieces63 -1 Mullard Thynstor tugger and modules64 - 10 assorted knobs St spindles65 -5 different thermostats, mainly bi-metal66 - Magnetic brake - stops rotation instantly67 - Low pressure 3 level switch68 - Heavy duty 4 pole contactor - 24v coil69 -225 watt pots 8 ohm70 -225 watt pots 1000 ohm71 -4 wire wound pots - 18, 33. 50 and 100 ohm72 - 1 1250 wart dimmer Ultra ref SE2073 -4 3 watt wire wound pots 50 ohm74 - 50 1/3 wan carbon film resistors food spread 10
valves75 - 20 2 watt carbeeri resistors 10 values76 - 30 1 ;tors 15 der values77 - 1 t-te, - _ _:able 1-60 mins78 - 5.5 ----------79-42a: a _e ertot ets 400v60 -2 7. eee rectifiers 30a81 -1 no-Jr.:mg sty dlok fuse.82 -4 pm , fuse holders and fuses83 - 1 t- : tent choke - your choice - 15. 20. 30, 40 or
65 svx:64 - 10 -1 of mamas voltage suppressor condensors85 - 1 mains shaded pie motor lie stack - It shah86 -2 5' ali fan blades fit 1. J shaft87 -2 3' plastic fan blades fit le' shaft88 - Mains motor suitable for above blades89 - 1 mains motor with gear box 1 rev per 24 hours90 - 1 mains motor with gear box 1 rev per 12 hours91 -2 mains motor with gear box 16rpm92 -4 fluorescent starters suit 4-80w tubes93 -4 11 pan moulded bases for relays94 -5 67G valve bases95 -4 skirted BSA valve bases96 - 1 thermostat for fridge97 -1 infra red fire element 1000 watts98 - 1 motorised stud switch (sit)93 -5 assorted ferrite shapes
100 -3 ferrite magnets101 -1 21/2 hours delay sweet'102 - 1 9v mains power supply unit103 - 1 Ery mains power supply unit104 - 1 41/2v mains power supply unit105 - 1 5µn flex plug and panel socket106 - 1 12v vibrating reed bleepers107 - 5' speaker size radio cabinet with handle108 -5 different multi way push switches109 - 101/4- spindle type volume controls110 - 10 slider type volume controls111 -2 musical boxes (less keys)112 -1 heating pad NO watts113 - 1 lm front end with tuning condensor and data114 - 1 lw amplifier Mullard 1172115 -Wall mounting thermostat 24v116 -3 pairs small 2ges. medium croc tips117 -4 pairs large (car size) crocodile dips118 - Teak effect extension 5' speaker cabinet119 - 1 log & 1 coal fibreglass fee fronts120 - cec.b. with 2 amp full wave and 7 other recs.121 -2 13 amp flush switched sockets122 - 10 mos twin screened flex white p.v.c outer123 - 100 plastic with hardened pin flex clips124 - 10 assorted slide switches
VENNER TIME SWITCHMars operates won 20 arrep switch, oneon and one off per 24 hrs repeats dailyautornaticatly correcting for thekrigtheratig or shortening day. Anthreers:ve tune switch but you can haveit for only £295 without case. metalcase -1295, adaptor kit to convert theinto a normal 241- time switch but withthe added advantage of up to 12 °rite:eftsper 2.thrs. This makes an iota!
Bond.condoler for the orirmeson heater. PriceGuaranteed 12 months of acaptor hi S 1230.
12 volt MOTOR BY SMITHSMete for use en cars. etc. these are verypowerful and easily reryersatee. See312' long by 3 Ma. They have a goodleng0th of la'
45spindle -
1/1 hp 13.V8 hp ES -75.16 hp £7.50
SOUND -TO UGHT UNIT
CornoINe kit of parts for a three channel sound to light antcentre:erg over 2030 wens oftghonig Use this at home if youwish tart a is plenty nagged enough for disco vaork.17. unit ishoused in an attractive two tone metal case and has controls foreach channel, and a master °Noe The two input and output areby 1r and three panel mourning fuse notp-tis provele
rt- at o tatootion. Afour pin plug and socket fa ate ease of- are Special price is £1495 m let ',-
THIS MONTH'S SNIPTOP OF THE POPS UGHTING
if you use our disco switch ONLY £6.90These have 12 x 10 amp changeover swficlieseach rated at 10 amps so a whole street couldhasty be le with one. Switches arteeeehle andocuid be set to grxe a running fight randomem-hes. etc. etc 230 volts man operation Brandrier. made by fittherweil. Offered at accrournateNon third ca you.
TANGENTIAL BLOW HEATERcy 1.! Solartron. as
:AS( blowr 3Xv: EIS5
. t aPlease add you E150 for 1 or 3 for C20 post paid26 Kw KIT sus ava4alem £4_95 E1-50 postor have 3 for E16 post paid.FROZEN PIPESCan be avoided by watefino our heating cable arornid them -15onus connected to mains costs only about leg per week to runHundreds of other uses as it is waterproof and very BeniciaResistance CO cemsMnetre Price 211penetre or 15m for £395.CORDLESS TELEPHONES-IT'S FOR YOU-Ou- even a you are in the belle es an enfinteextension any room and even in the garden - have one onapproval or come and try one here BT approved E120 not yetapproved ES& Both memorySOCKETS
tweePLUGS ETC for10 81 phones
Master socketthas surge arrestor- ringing condenser etre and tar.B.T.ping 1395Enension socketDual adaptor s(2 fromanesocked. 1355Cordterminahrgwith B.T. plug 3 metresKit for convening old entry terminal box to new B.T.master socket complete with 4 core cable, cable dips and2 BT extension sockets 111.50
25A ELECTRICAL PROGRAMMERLearn in your steep_ Have ratio °lees./ andtett. being as you wake - switch lghts toward off intruders - have a warm house to comehome to. You OM do a9 these and more. By afamous maker with 25 amp owe( send,Independent 60 minute mernoiy jogger.A beautiful wet at MO
THE AMSTRAD STEREO TUNERThis ready assembted unit is the ideal tuner to a nerds centre c.an arrepefer. it can also be quickly made into a personal stereorack. - easy to carry about and wheel will give you superbept.,Other Lses are a -get you to sleep radio-. you COURI eventake aweer
you to use in the lounge when the rest of the larr y wart SO
mew programmes in which you are not intwinted You can listento some music instead.Some of the feature are: long wave band 115- 1701014 mecumwave band 525 - 1650101c FM band 117 - 103 MHz. mono,stereo& AFC syntchable, fully assembled and fuLty a&gned. Fue wieing Leotiara shoving you how to connect to ampefer o headphceer artadetaes of suitable FM aerial (note fence rod aerial is iree.ded forrriedum and long wave bands). Alt made up on very comp eotboard_Offered at a fraction of its cost only E4.95
IONISER KITRefresh you. home. office. shop. won room. etc with arear: ee ION generator. Males you feel better and ou=st harder-a complete mans operated kit case creeeclectE1195 PA/5 12 CO Past -
4/5A BATTERY CHARGERTransformer and rectifier £3.95 & El post 3 Kits E12.MINI MONO AMP on px.n_ side r a 2' (app)Fined volume control and a hole for a tone con-trol shoukt you require is. The and feehas three transistors and we ester,ate the output to be 3W rms.More tectmmai date we be includedwith the amp. Brand new.perfect condition, offered at the veryUw price of E1_15 each. or 10 Cr 110.00.
BULL (Electrical) Ltd.(Dept. ELI, 34 36 AMERICA LANE.
HAYWARDS HEATH, SUSSEX RH16 30UtutAntsed
30 V30
ORDER TERMS: Cash. P.O.or cheque with order. Ordersunder £20 add El sir. -ix cherge. heoraley account orders acceptedMorn schools and pubic companies Access & !Iced ordersaccepted day or eight Haywards Heath 101.44)4lets.O1 Bulk ordererphone for cnote- Shop open 9.1:0- 530. Mon to Fri. not Saturday_
TWO POUNDERSFctil,,,,t3 the Popo:early of E!..:ERS DOZEN EtPARCELS. weare now ntrc _ - - scene BAKERSDOZEN £2 PARCELS. We i, you MI agree thatmost are erceptional barge = - . ou can sell get a bitextra, as .rth the El parcel. .-a buy 12 iou getanother free,
2P1 -24 hour time switch with 2 °reefs. an ideal heatingprogrammer
2P2 -Wall mounting thermostat. high precision withmercury switch and thermostat
2P3 - Variable and reversible 8-12, power set:ply, ideal formodel control
2P4 - 24 volt psu with separate channels for stereo made forMullard UNILEX Amplifiers_
2P5 - 12 volt psu 750 ma output - plastic cased2P6 -100 watt mains to 115 volts auto -transformer with
voltage tappings2P7 - Mini key, 16 button membrane keyboard, fist price over
£12. as used on PRESTEL2P8 -Mains motor with gear box arid variable speed
selector. Series wound so suitable far further speedcontrol
2P9 -Time. and set snitch Boxed, glass fronted and withknobs_ Controls up to 15 amps. Ideal to programetectnc heaters. battery chargers etc
2P10 -12 von 5 amp mains transformer -tow volt winding onseparate bobbin and easy to remove to convert tosower voltages for higher currents
21.11 - Power amp module Munard Unilex EP9000 (note stereopee -amp module Unilex 9001 is 80216
2P12 -Disk or Tape precision motor -has balanced rotor andis reversible 230v mains operated 1500 rpm
2P13 -Sun Lamp switch stays on for 1,1 It, or 1 hr dependingon setting of grub screw
2P14 - Mug Stop kit - when thrown emit piercing squawk2P15 -Interupted Beam let for burglar alarms, counters. etc7P16 -Lockable metal box with 2 keys. ideal for your toots2P17 -1 rev per minute mains driven motor with gear boa.
ideal to operate mirror ball2P18 - Liquidgas strut off valve mains solenoid operated7P19 - Disoa switch -motor drives 6 or more 10 amp change
over micro switches supplied ready for mainsoperation2P20extension
lead. 2 core- ideal most Black andmetresDecker garden tools
2P21 -10 watt amplifier. Multard module reference 11732P22 - Motor driven switch 20 secs on or off after push2P24 -Clockwork operated 12 hour switch ISA 250V with
clutch2P25 -1000 watt flasher mains motor driven2P26 -Counter resenable mains operated 4 digit2P27 - Goodman Speaker 6 inch round Bohm 12 watt2P28 -Drill Pump - always useful couples to any make
portable drill2P29 - 24 position Yaxley switch contacts rated SA -1.t spindle2P30 -15 metres 6 way telephone or inteeconnecting wire2P31 -4 metres 98 way interconnecting wire easy to strip to
use the cores separately2P32 - Hot Wire amp meter - 41/2 round surface mounting -
old but working and definitely a bit of history2P33 -0-30 amp meter r round panel mounting with shunt ex
ministry equipment2P34 - Solenoid Air Valve mains operated2P35 - Battery charger kit comprising mains transformer, fun
wave rectifier and meter, suitable for charging 6v or12v
2P36 -20 Amp meter, with shunt unused but ex -equipment2P37 - 0-l00 micro amp meter. 2' square flush mounting good
make2P39 - 200 R.P.M. Geared Mains Motor 1' stack quite
powerful, definitely large enough to drive a rotatingaerial or a tumbler for polishing stones etc
2P4t - Liquid crystal display, 8 digit 13mm black on saver2P42 - Tubular heater, 60 watt per h, unused but slightlystorage scel, made by G.EC. perfect order (must becollected by appointment)2P43 - Smail type blower or extract°r fan, motor inset sovery compact, unused_2P36 - 0-20 amp panel mounting meter with fated shueex equipment but guaranteed2P44 Inverter to operate 21" 13 watt fluorescent tubeof 12 volts2P45 Our famous dill control kit complete and with
Preparedcase2P47 - Joy switch kit complete as previously sold2P48 - Telephone ringing unit reduces mass to 50 voltsand changes frequency from 50 Hz to 25 Hz to one rightringing tone2P49 - Fee Alarm break glass switch in heavy
CPA STARTER/CHARGER KITRat Battery! Don't worry you win start your car in a fewminutes with this unit- 250 watt transformer 20 amp rectifiers.case are. aft pans with data E16.50 or without case E15.00 postpaid.
SUPER H.F. SPEAKER CABINETMade for an expensive Hi -F outfit Willsuit any decor, is resonance free, cutouts for 8' woofer, 23/4* mid range arid2W tweeter. Front is black and thecompleted unit most pleasing. Priceper pair £690 carriage E3.50.
OTHER POPULAR PROJECTS£1495B.g
Ear, fistestnrcugh wars-.._.Silent Sentinel Ultra Sonic Transmitter and Receiver -193.50Car Light left on Alarm E3.503 - 30v Variable Power Supply 511102 Short & M.edium Wave Crystal Radio E3.99Rad;oSlethosespe -fault finding aid 14.80Morse Trai ner - complete with key £299Drill Control Kit 53-95Transmitter Surveillance Kit
£690123
I1RFa.ReceiyMikeerKit-for surveillance or iximnal RA E3 50Insulation Tester -electronic megger_ E7 95Matchbox Radio -receives Medium Wave. £2.9540 watt amp -Hr -Fl 20hz-20kFlz115 Watt Amplifier Selz 25kHz £13.50Power Supply for 115 watt amp £9.50
67 EEFebruary 1986
Appointments Appointments Vacant display adrerrisemenmrates available on request from E7ektor El'ectronics Glentop Publishers Limited.Srandfast House. Bath Place High Street. Barnet Heirs ENS 1EDPhone 01 441 4130 or 0227 601Ce_
SALES AND MARKETINGCAD/CAM - GRAPHICS - PRINTERSMINI/MICRO - DEC IBM - ACT DGOLIVETTI CCTV VIDEO....
As the leading specialist recruitment consultancy operating within the electronics in-dustry, we have a broad selection of sales, marketing and applications vacancies.
We are interested in talking to both recently qualified engineers and senior manage-ment within the industry.
To discuss these opportunities in total confidence please telephone Gary Young(Systems Sales Division) on Lewes (0273) 471271 or, alternatively, write to the addressbelow, enclosing a full C.V.
Electronics Recruitment Company UKVEl:1.C. House. 32-33 North Street. Lewes. East Sussex 8N7 2PQ. Tel Lewes (0273) 471271
ALL SYSTEMS GO! to £17,000A young Communications company offering a bright, informal environment combined with big company benefits, has continued its expansion intonew fields of micro -based Systems Development and offers challenge and scope to both Hardware and Software Design Engineers with at least18 months experience.
We have also been contacted by an established market leader who has started breaking new ground with its major Real Time Software DevelopmentProgram, and offers an ideal opportunity for career development. Working at the frontiers in "C" and CORAL, they would like to meet you if you arefamiliar with FORTRAN, PASCAL or ALGOL and are ready to move into sophisticated Real Time applications.
Contact Alison, Shaw House, 2 Tunsgate, Guildford, Surrey. GU1 3QTTel: (0483) 65566 (out of hours 0306 883489)We are working closely with a company who are committed to expanding their Electronics Design function. To fulfil this requirement they wish to talkto Engineers with at least 2 years experience, whose ability could be channelled into specific areas.
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The company offers excellent salaries and benefits and senior positions for proven experience.
Contact Judith, 105 St. Peter's Street, St Albans, Herts. AU 3HHTel.: (0727) 35116. (out of hours 0480 62081).
ment PersonnelRecruitment Selection & Search Consultants
EEFebruary 1986
68
DESIGNING A CLOSEDLOUDSPEAKER BOX
There are currently twoloudspeaker systems:closed or total (US) box,sometimes unfortunatelyreferred to as infinitebaffle, and the reflex box.The latter is typified by ahole in its front panel(other than the drive unitapertures), while theclosed box is exactly whatits name implies. Of thetwo, the closed box is
nowadays the preferredsystem with reputablemanufacturers and DIY en-thusiasts alike. Because ofthat, this article will de-scribe briefly what is in-volved in the design of aclosed box as far as bassloading is concerned. In-terested readers may notethat the design of an ex-cellent cross -over networkwas featured in theDecember 1985 issue ofElektor Electronics (p. 28).It should be noted that thedesign and construction ofa loudspeaker enclosureare well within the com-petence of most of us andthat if the considerationsgiven in this article areobserved, the results willapproach those of pro-prietary units.The net volume of theenclosure should ideallybe an optimum for agiven drive unit but, unfor-
tunately, this is not alwayspracticable, nor does itnecessarily result in a per-formance that satisfies allpersonal tastes andpreferences. It is, none theless, possible to arrive atan acceptable com-promise in virtually everyindividual case.
The drive unitIt is important before buy-ing the drive unit to con-sider the followingcarefully because this unitwill largely determinewhat sort of enclosure isneeded.Knowing the followingthree characteristics of thedrive unit is essential forthe computation of an op-timum enclosure: (a) theresonant frequency, f, in
free air; (b) the Q factor,QTS, at the resonant fre-quency; and the suspen-sion compliance, Vas, inlitres. All reputablemanufacturers publishthese characteristics.
Q factor of thesystemThe frequency response ofa closed -box system is asecond -order, i.e. 12 dB peroctave, high-pass filterfunction. The Q value ofthe loudspeaker system,Qrc, determines the shapeof the response character-istic. Fig. 1 gives thecharacteristics for anumber of loudspeakersystems with different Qrcvalues. It shows that theoptimum second -order
Butterworth curve is ob-tained at a Q7c value of11\f2, i.e. 0.707. Values be-tween 0.5 and 1.0 are per-fectly acceptable, butthose above 1.0 result in adistinct peak and lead topoor step response, whichis definitely not accept-able in hi-fi systems. Fig. 2illustrates the differencesin step response for vary-ing values of Qrc.
The arithmeticIt is safe to start the com-putations with a Qrc valueof 0.7; when this results inunacceptable values forthe resonant frequency, f,of the system, or volume ofthe box, Vs, other values ofQrc may be tried.The resonant frequency ofthe loudspeaker system is
69 EEFebruary 1986
calculated first:
fc=fs(QtclQis) [Hz] (1)
At a Q -c of 0.7, the res-onant frequency of thesystem is also the -3 dBpoint, 13, of the box. Othervalues of ac cause a shiftas shown in Fig. 3. For in-stance, at a value of 0.5, 13is one and a half timesthe value of fc.If, in formula (1), the valuesof as and fs are stated bythe manufacturer to be0.35 and 30 Hz re-spectively,
fc=30(0.7i0.35)=60 Hz
The volume of the box iscalculated from:
VB= VABi(fc21/52 -1) [I) (2)
If, for instance, the manu-facturer's stated value ofVAs is 0.09 m3, i.e., 90 litres,
the net volume of theenclosure is
V6=9016021302-1)=30 litres.
Summarizing: if a driveunit with k.=30 Hz;Qm=0.35; and VA5=0.09 m3is built into a 0.03 m3enclosure, the loud-speaker system will have aresonant frequency of60 Hz at the ideal Qrcvalue of 0.7.If these results are not ac-ceptable, one of theparameters may bechanged. It is clear fromthe foregoing, however,that QIC, fc, and Vs are in-terdependent: changeone, and you change allthree.If, for example, the systemresonant frequency of60 Hz is considered toohigh, insert the desiredvalue, say, 45 Hz, into for-mula (1) and calculate ac
from a rehash of theformula:
Qtc= QtsfcIfs
=0.35X1.5=0.525
Then, insert the new valueof fc.--45 Hz into formula (2)and calculate VB:
V5 =9014521302-1)
=9011.25=72 litres
If, however, an enclosurevolume of 30 litres wasconsidered rather high,Qrc could be takensomewhat higher. It will befound that for the sameloudspeaker parameters,and taking Qrc=1, thesystem resonant frequency,/c, will be 86 Hz, and thenet volume of theenclosure, 143, will be 12.5litres.
Fig 1. Effect of the Q:7:value on the frequencyresponse ofa loudspeakersystem. Designers aener-ally consider a value of1/V-2= 0707 as ideal.
Fig. 2. Normeli7ed stepresponse of the closed -boxsystem. The higher theQaz the poorer the stepresponse: a good reasonfor not adopting a OTCvalue above 1.0.
Fla 3. The relation be-tween the resonant fre-
quency of the closed box,fr., and the -3 dB, fE, pointdepends on the an- value.At a OTC value of aZ
As a rule of thumb: thelarger the enclosure, thelower the Q and the res-onant frequency. A (too)small box will result in ahigh system Q and a highresonant frequency. JR
EEFebruary 1986
70
RF CIRCUIT DESIGNThis month we commence a short series of articles on thedesign of RF circuits. Each of the articles will merely pro-vide a framework and not necessarily a complete designof the relevant circuit.
Test oscillator
Cia1:31.3L1 0 00 L.NJOCIC300000C1
313COOCICIOU0Ci0I 0141Lar,a1;u:Lu.....1-Al2
CI 0 0-0.0 0 0'0 0 LI0000000C1001_O. 13 Et 0-440CI cioo01-Wagii-13 O. o C.
Fig. 1. Thecopper -claduniversal RFboard Type85000 has fifty-seven islandsand threeisolated tracksfor supplyvoltage or con-trol voltage -such as AGC -lines.
Fig. 2. Exampleof a voltage -controlled oscil-lator constructedon a copper -cladboard.
This first article deals with a virtuallyindispensable unit in RF design: asimple signal generator. This unitprovides a signal at a certain fre-quency and amplitude, and may befrequency- or amplitude -modulated.It is intended to cover a frequencyrange of 2 - 150 MHz in a number ofbands.
Universal RFboardThe Type 85000 (available throughour Readers Services - see page 80)is an unpierced copper -clad board
with fifty-seven isolated islands andthree isolated tracks. It is particularlysuited to RF circuits because of thelarge earth plane, and enables theconnections of all components to bekept really short -a prerequisite inRF design. Examples of the boardproper and of a voltage -controlledoscillator constructed on a copper -clad board are shown in thephotographs in Figures 1 and 2 re-spectively.
Block diagramThe block diagram in Fig. 3 showsthat the test oscillator consists ofthree separate sections: the oscil-lator, amplitude control; and outputbuffer. The oscillator is based on aMOSFET, whose mutual conduc-tance, gm, and consequently the am-plitude of its output signal, iscontrolled by a direct voltage ongate 2.The amplitude control sectionmonitors the oscillator output andcontrols gate 2 of the MOSFETaccordingly, so that a reasonablyconstant -level oscillator signal is ob-tained. This arrangement has the ad-vantage that it enables the oscillatorto work over a fairly wide frequencyrange.
The buffer section provides an out-put impedance of 50 ohms.
Circuit descriptionThe oscillator - see Fig. 2 - is de-signed around Ti: its frequency -determining components are Li andvaractors DI and Da These variable -capacitance diodes are controlledby Pt: a high voltage across themcauses a small capacitance, and viceversa. The frequency of an LC os-cillator is given by
f=1/2n [Hz] (1)
where f is the frequency of the oscil-lator. L is the inductance in henries(H), and C is the total capacitance ofthe two varactors in series in farads(F).The ratio between the lowest and thehighest oscillator frequency, ft and f2respectively, depends on the squareroot of the ratio between the maxi-mum and minimum capacitance, C2and CI respectively, of the varactors:
/112= C2:C (2)
The maximum capacitance of theType BB106 varactor is about fivetimes the minimum capacitance for areverse bias voltage of 3 of 25 V, sothat the frequency ratio is roughly2.236, or rather more than an octave.The highest attainable frequency isaround 300 MHz, but this depends,of course, also on the value of Lt.The series combination L2 -L3 -L4 is in-tended as a sort of wide -band choke.The inductance of LA (100 mH) israther too large for high frequencies,because the reactance at those fre-quencies amounts to a few kiloohmsowing to parasitic capacitances.Lower inductances are, therefore,used for the higher frequencies: L2and L2. Inductor L2 is only of use atfrequencies above 50 MHz: if the os-cillator is not required to work onthese frequencies, this coil may beomitted and replaced by a wire link.
3
AmplitudeControl
03,T2
Oscillator
71,131,132,11
BufferStage
T3
50 SI
85125-3
The signal at gate 1 of the oscillator isrectified by Di and smoothed byR2 -C3. As soon as the resulting directvoltage rises above 600 mV, the Iran-
' sistor tends to conduct harder.which causes the potential at gate 2.and therefore the oscillator output, todrop. This regulation is necessary ifthe oscillator is to work over a rela-tively wide frequency range. Also,without regulation, the output levelwould vary greatly with tuning: in thepresent circuit, the output level vari-ation is held within 10 dB. i.e.. a ratioof about 1:3.
The oscillator signal is applied viacapacitive divider C' -Cs to transistorT3, which is connected as a sourcefollower. The mutual conductance,gm, of this FET is about 20 mS, sothat, since
Z.=1/gm [Q] (3)
the output impedance, Zo, is50 ohms.
111 EE
February 1986
Fig. 3. Blockdiagram of theRF test oscillator.
Mutual conductanceis the ratio of thechange in outputcurrent to thechange in inputvoltage when theoutput voltage isheld constant. It ismeasured in siemens(S), which replacedthe mho (reciprocalof ohm) some timeago.
Fig. 4. Circuitdiaaram of theRF test oscillator.
30 V
P1
0
BF900; BF905; BF907; BF961; BF981G2 02
GI
R4
50klin.
R3
T2
BF494
D3
11C8
1N4148
R2 0CijmoCl R1 = C4
_M0 -68p 760p 52 70p
CS00
T560p
I
Ci117n
BF246C
1p
C7 R6Nom
7p 0""
R7
0<30 mA
12 V
O
-10.._20 dBm50 !!.
S C10
Al 0 10100n
8.5125-4
®
BF246C BF494
Ship C 8G E
T1 = BF900; BF905; BF907; BF961; BF981D1, D2= BB 106
EEFebruary 1986
Fig 5. Suggestedcomponentlayout of the RFtest oscillator.
Parts list
Resistors:
RI:RERs= 100kR:= 470kR4 = 330k
R s = 6E0S2
Rs= 10MRr = 2204
= 50k linear preset
Capacitors:
CI;C:;Cs =560pC3 = 68p
C4 = 330p
Cs;Cs= 1pC7 = 10p
CECII =47nCto = 100n
Inductors:
LI =0.1...10mH (seetext)
Lz= 5 turns 0.3 mm dia.(30 SWG) enamelledcopper wire on ferritebead 3 x 3 mm.
1-3 = 1mH choke
1-1 = 100mH choke
Semiconductors:
T1= BF900 or BF905 orB1907 or BF961 orBF981
T2=131494T3 = BF246C
D1;02=86106 Isee text)D3 = 1N4148
Universal RI boardType 85000
(available throughReaders Services)
Fig 6 Circuit ofa possible50 -ohm one-stepattenuator. Theresistor values inthe ac-companyingtable arecalculated: in apractical circuit,the nearest stan-dard valuesshould be used.
Frequency rangeIf varactors Type BB106 are used, theoscillator can be tuned over a fre-quency range of one octave, i.e., themaximum frequency is about twicethe minimum frequency. To cover afrequency range of, say, 2 MHz to32 MHz (four octaves) four differentcoils are required for the Li position.Since it is not really possible to use alarge tapped coil and a range switch- because the resulting straycapacitances would causeunreliable and unstable operation -separate plug-in coils must be usedfor Li. At the highest frequencies -above about 150 MHz - the coilshould be air -cored; below 150 MHz,it needs to be wound on a dust -irontoroid. Some examples of suitablecoils for frequency ranges as statedare: 150-300 MHz: 50 mm enamelled
copper wire, SWG20 (1 mm dia.),one turn; 75-150 MHz: 9 turns 24 SWG
(0.6 mm dia.) enamelled copperwire on a Type T50/12 toroid; 7.5-15.0 MHz: 70 turns SWG 30
(0.3 mm dia.) on a Type T50/2toroid.Although the Type BB106 varactorcan be used right across the fre-quency range, a Type BB105 is betterif most of the work is carried outabove 100 MHz, while a Type KV1226is preferable below 20 MHz.
ModulationFrequency -modulating the oscillatorsignal is achieved by applying themodulating voltage to the wiper oftuning potentiometer P1 via a seriesresistor and coupling capacitor. It ispossible to add a potentiometer foradjusting the level of the modulatingvoltage, i.e. the frequency deviation.Amplitude modulation could be ar-ranged by injecting the modulatingsignal into gate 2 of the oscillator.This is, however, not a satisfactorymethod because the internalcapacitances of the MOSFET varywith the modulating voltage,resulting in not only amplitudemodulation, but also frequencymodulation, of the oscillator signal. Itis, therefore, better to modulate withthe aid of an additional MOSFETconnected between the oscillatorand the buffer.
Output attenuatorIt is very useful in many applicationsif the output signal can be attenuatedin suitable steps. A suitable circuitfor a one-step attenuator is shown in
6
500
r
RA
L _ _
RA
1
LC50son
_J
Attenuation RA RB
2 dB 5,7 n 215,2 n4 cat 11,3 El 104,8 9.8 dB 215 n 47,32
10 dB 26 El 35 f.2
20 dB 41 El 10 9.85125-6
Fig. 6. Several of these circuits maybe connected in series to obtainswitch -selected stepped attenu-ations of, say, 2 dB, 4 dB, 8 dB, and soon. Note, however, that the greaterthe attenuation, the more attentionshould be paid to screening anddecoupling. Any signal "leaks" atthe output at low levels spoil the ac-
curacy of the attenuator. The tableaccompanying Fig. 6 givescalculated values for the attenuatorresistors; in practice, the neareststandard values in the Ell or E24series should be used. Note thatwirewound resistors should never beused in RF circuits owing to theirhigh self-inductance. JB:BL
113 etFebruary 1986
SWITCH 3OARDBACK NUMBERS Elektor 68to 105 - offers? J.R. Williams,11 Butlers Gardens, Frome,Somerset BA11 1LZ.
FOR SALE 10 Plug-in liquidlevel detectors 3 probe type;high and low probes plus com-mon, £10 each. Mr D. Harries,17 Eccleshall Avenue, Oxley,Wolverhampton VVV10 6TN.Tel. (0902) 780958.
WANTED: Servicemanual /Cct diagram forAirmec VHF/ FM Sig. Gener-ator type 211 (Radivet). Price Erdetails to P. Nash, c/o 20Chorley New Road, Bolton BL14AP. Tel. 0204 35239.
ELEKTOR back numbers: a
hardbound set of 1977 issues(nos. 21 to 32). Almost mintcondition. £20 4- £2 P&P (inU.K.). Mr M. Ling, Rose Cot-tage, Margate Hill, Acol, Bir-chington, Kent.
RADIO AND TV SERVICINGVol. 1-5, 1955-56, 1958-59,1965-72 inc. 14 volumes total,£40 o.n.o. ÷ postage, Tel.Medway 681006.
EXATRON Continuous LoopComputer Data Storage Devicewith book containing circuitdiagram. RS232 Interface. £65o.n.o. Mr S. Parsons, 4 CliftonPlace, Ilfracombe, N. DevonEX34 9JJ. Tel. 0271 66431.
WANTED: Every and any typeof book(s) on radio construc-tion, AND on making digitalclocks. Call D. Jones, 01 2494829.
CMB 64, battery backed up8K RAM pack, £25. R Thomp-kinson, 66A Harold Street,Grimsby, S. Humberside DN327NQ.
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soldout!
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4. The Advertiser's lull name and address must ac-company each advertisement submitted.The prepaid rate for Classified Advertisements is25 pence per word (minimum 12 words). Semi -display setting 16.50 per single column cen-timetre (minimum 2.5 cars.). Please add 15%VAT to total. All cheques, postal orders, etc.. to.he made payable to Glentop Publishers Ltd.Treasury notes should always be sent by regis-trered post.
Advertisements, together with remittance,should be sent to: Classified AdvertisementDept., Elektor Electronics, Glentop PublishersLtd.. Standfast House, Bath Place, High Street.Barnet, London EN5 1ED.
THE SCIENTIFIC WIRE COMPANY811 Forest Road, London E17.
Telephone 01-531 1568ENAMELLED COPPER WIRE
SWG 1 lb 8 oz 4 oz 2 oz8 to 34 3.63 2.09 1.10 0.88
35 to 39 3.82 2.31 1.27 0.9340 to 43 6.00 3.20 2.25 1.6144 to 47 8.67 5.80 3.49 2.7548 15.96 9.58 6.38 3.69
SILVER PLATED COPPER WIRE14 to 30 9.09 5.20 2.93 1.97
TINNED COPPER WIRE14 to 30 3.97 2.41 1.39 0.94Flu xcoreSolder 5.90 3.25 1.82 0.94
Pnces include P&P VAT. Orders under £2 add 20p.SAE for list of copper and resistance wire.
Dealer enquiries welcome
34:41111IJZIC0110:itiC121,ALL THE LATEST FASTEST DEVICES NOT TOBE CONFUSED WITH SLOWER OLD STOCK
OFFERED ELSEWHEREDRAM5v NMOS 150rts
EPROM5v NMOS 250n5
4164 64k x I .. £0.95 2716 2k x 8 ... £ 2.9541256 256kx 1 .. £2.80 2732 4k x 8 ... £ 2.754416 16k x 4 .. . £2.95 2764 8k x 8 ... £ 1.9541254 64k x 4 ... £5.90 27128 16kx8 £ 2.85SRAM 27256 32kx8 _ £ 4.505v CMOS 150n5 5v CMOS 250nS6116 2k x 8 . . £1.49 27C64 8k x 8 . £ 8.506264 8k x 8 E3.19 27C256 32k x 8 £15.00
SPECIAL OFFER 2716 Intel 450nS (Ex -equip.)has been cleaned, tested & UV erased £1.50LINEARBIFETS
Each 5 OTHER LINEAREach 5
TL-072CP .... SOp £2.10 NE.555 ... 19p £0.90TLO74CN 80p £3.50 LM311P .._ 39p E1.80TL1352CP 40p £1.80 LM324 .. 39p £1.80TLC-54CP . 85p £3.50 L.M348N ... 39p £1.80REGULATORS 124358 ... 39p £1.80(All T0220 package) SN75154N 95p £4.507812 .... 35p £1.60 OPOTCP £1.20 £5.0078M12 . 35p £1.60L2f337 £1.20 £6.50ORDERS OVER £25 DEDUCT 10% DISCOUNT ADD
15% V.A.T. POST FREEORDERS UNDER £25 ADD 15% V.A.T. PLUS 50p P&P
Lists of other offers processors etc. sentDESPATCH BY RETURN C.W.O.
MICROKIT LIMITEDMANOR PARK RAUNDS NORTHANTS NN9 6PD
,..,..--Falc.on'DIY SPEAKERS/.... ,
ASend for our FREE price listPL15 all we ask is a large S.A.E.
(22p stamp) (Overseas U.S. $2 bill)(Europe - 2 International reply coupons)
SYSTEM DESIGNS (Total Kits):Focal, KEF Constructor Series, etc.
DRIVE UNITS Focal, KEF, Audax,Celestion, Coles, Peerless, Seas,
Siare, Scanspeak, etc.Also Groupi Disco Units
CROSSOVER NETWORKS -Active 8- Passive Components,
Accessories etc.Expert advice via our enquiry service.
ELEKTORiKEF PL301Units, Networks Et Components
Full details fromFALCON ELECTRONICS tannEL,
Tabor House, Mulbarton,Norfolk NR14 UT
(Proprietors: Falcon Acoustics Ltd.)
ADVERTISERS' INDEXAppointments Vacant 67
J. Bull (Electrical) 66
C.P.L. Electronics 16Cricklewood Electronics 15
Display Electronics 79
East Cornwall Components 26Executive Recruitment Services 67
Falcon Electronics 76
Greenweld Electronics 37
Hart Electronic Kits 65
Keytronics 55
Management Personnel 67Maplin Electronic Supplies 80Microkit 76
Scientific Wire Comp. 76Solascan Micro Systems 76
Technomatic 2 Er 4TK Electronics 37
Watford Electronics 6 Er 7Wilmslow Audio 84
6809HARDWARE/SOFTWARE
HARDWARE: lELEKTORBUS COMPATIBLE)iPCS s £32.95 +VAT - Also Available Built andTested)6839 CPU CARD: Full RS232 Serial Interface (6551
ACIA) (with TTL to drive CassetteInterface)Two Port Parallel Interlace 16$21 PIA)Up to 16K EPROM/RAM on board1MHz or 2MHz operation
64K Static RAM Card: Up to eight 2K/8K devices(with battery backup)
Floppy Disk Interface Card
SOFTWARE: System Monitor 121(1 . E10.95Disassembles 121(1 E10.95Editor/Assembler (4K) : (21.95Fig FORTH Language (81() E43.95
Cheques,Postal Orders accepted
For further details send SAE 19" 4")
VATVATVATVAT
SOLASCAN MICRO -SYSTEMS LIMITED8 OAKLANDS GROVE. COWPLAIN, HAMPSHIRETELEPHONE 0705 263956
ELEKTOR KITS assembled and tested* by Elec-tronics Apprentices under supervision for as littleas DO', inside a purpose-built electronics work-shop (*depending on type of kit and complexity).Contact: A.J. Smith, Dept. K.A., ElectronicsWorkshop, Lincoln IT.E.C., Dean Road, LincolnLN2 4JZ. Tel. 0522 43532.
CLASSIFIED ADVERTISEMENT ORDER FORMRate: 25p per word (min. 12 words) Semi -display setting: £6.50 per single column cm.Please insert the advertisement below in the next available issue of Elektor Electronics. I enclose cheque P.O. for £ (cheques &Pos al Orders should be made payable to Glentop Publishers Ltd.)
NAME:
ADDRESS:SIGNATURE:
Please post to the address given at top of page.
79 EE
February 1286
EX -STOCK INTEGRATED CIRCUITS4164 200ns D RAMS 8 for £14.954116300 ns £1.502112 £10.00 2114 £2.50 2102EPROMS 2716 £4.50 2732
£2.00 6116£3.00 2764
£2.50£4.95
27128 £5.50 6800 £2.50 6821 £1.00 88409 £8.006809 £10.00 8085 £5.50 8088 £15.00 8251 £7.008748 £15.00.
Thousands of IC's EX STOCK send SAE for Ilst.
RECHARGEABLE 8A /RSDry Fit MAINTENANCE FREE by Sonnenschein S YuasaA300 07191315 12v 3ari as RS 591-770 NEW £13.95A300 07191312 6 v 3ah as RS 591.360 NEW £9.95A300 07191202 6-0-5v 1.855 as RS 591.382 Ex Eddb£5.99 3.6v 100 rah PCB mount as RS591-477 NEW (1.00
DIFIeJapanese al .eight. 80 rack double sideddisk drives by TEAC. TOSHIBA etc Sold asNEWwi1h 90 day guarantee ONLY £125.00.SUGART SA400 SS FH 35 TRK £55.00SIEMANS FDD100 SS FH 40 TRK £75.00carriage on 57V ' drives £5.50Brand N EW metal cases with internal PSU etcfor above drives, below cosi!!!DSKC 1 for 2 HH or 1 FH 51:- drive £39.95+ pp£4.50 DSKC 2 for 1 HH or1 FH51:" drive£29.95 + pp £4.508 Refurbished standard unitsSUGART 801 SS £175.00 + pp £8.50SUGART 851 DS £250.00 + pp £8.50
IRS -11Atillf tgivg in s2g c a s ecomplete with PSU etc, £595.008 DRIVE PSU for 2 drive units £45.00Hard Disk DrivesDRE/DIABLO Series 30 2.5 Mb front load,£525.00. Exchangeable version £295.00ME3029 PSU for above £95.00DIABLO 44/DRE4000A, B 5+5 Mb fromEsVAWK 5+5 Mb £795.00CDC 9762 BO Mb RM03 etc £2500.00PERTEC 03422 5+5 Mb £495.00RODIME 10MB ST506 Winchester NEW£299.00BASF 8172 23Mb Winchesters, as seen£199.00Carriage on other drives £10.00.Unless stated all drives are refurbished with90 day guarantee. Many other drives andspares in stock- call Sales office
MODEMSJoin the communications revolution with oursuper range of DATA MODEMS. prices andspecifications to suit all applications andbudgets._BRAND NEW State of the art productsDACOM DSL2123 Multi standard 300-300.1200.75 Auto answer etc £268.00DACOM DSI.2123AD Auto del, smartmodern with multi standard AUTO SPEEDdetect and data buffer with now controletc £365.00DACOM DSL2123GT The CREAM of theintelligent moderns auto del auto call. index.buffer etc etc £498.00STEEBECK S81212 V22 1200 baud FULLDUPLEX. sync or async optional auto dal.
E485.00TRANSDATA 3074 Acoustic coupler 300baud full duplex. Originate only,RS232 £49.00
141-9.11,---YriTS-11-
Ex BRITISH TELECOM full spec CCITT.ruggeclised bargain otters Sold TESTED withdata Wig work on any MICRO or system withRS232 Interface.DATEL 28 300 Baud Modem see SPECIALOFFER.MODEM 13A 300 baud unit only 2" high fitsunder Ohdne CALL mode only £45.00MODEM 20-1.75-1200 baud. Compact unitfor use as subscriber end to PRESTEL.TELECOM GOLD, MICRONET etc £39.95+ op £1150MODEM 20-21200-75 baud. Same as 20-1 butTor computer end, £85.00 + pap £6.50DATEL 2412 Made by SE tabs for BT this twopart unit is for synthronlous data Mks at1203or 2400 baud using 2780/3780protocol etc, Many features include 2 or 4 wireworking, self test auto answer etcCOST OVER £800 Our price ONLY £199+ pp £8.00DATEL 4800, RACAL MPS4800 baudmodem. EX BT good woredng order, ONLY£295.00 + pp £8.00
SUMMER OFFERMODEM TG2393. Ex 81, Up to 1200 baud, fulldude, over4 wire or haff duplex over2 wiretinaONLY £85.00 PER PAIR + pp £10.03
For more informationCONTACT OUR SALES OFFICE
NOT LINE DATA VASE
DISTEL©The ORIGINAL FREE OF CHARGE dial up database Buy, browse or place YOUR OWN AD forgoods or services to selL 1000's of stock items,
spares and one off bargains. Updated daily.ON LINE NOW. CCITT, 8 bit word, no parity.
For 300 baud modems call 01-679 1888For 1200-75 baud modems call 01-679 6183
COOLING _FANSKeePycLirnOt Carta cooLandRELtABLE wAnour range of COOLING FANSETRI 126LF21 240v 5 blade equipment fanDim 80 x80 x38nun £9.95ETRI 88XU01 Dim. 92 x92 x 25mm24Oi ecubment fart complete with fingerguard NEW £9.95GOULD 18-3AR Dim 3- x 3- x 2.5- compactvery quiet running 240v operation.NEW £6.95.BUHLER 89.11.22 8-16v DC micro miniaturereversible fan. Uses a lxushless servo motor forextremely high air flow, also silent running andguaranteed 10.000 hr life Measures only 62 x
mrn. Current cost £32.00. OUR PRICEONLY £12.95 complete with dataMUFFIN -CENTAUR standard 4- x 4- x 1.25"farts 110v OR 240v NEW at £10.50 or testedEX EQUIPMENT 240v (625 or 110v C4.95.
1000's of other fans Ea Stock.Call for Details Post & Packing on all fans IZZOO.
OWERTY KEYBOARDSManufacturer's BRAND NEW surplusALPHAMERIC 7204/60 Full travel ASCII.60 key with parallel output and strobe£39.95DEC LA34 Uncoiled keyboard with 67quality gold plated switches on X -Y matrix -ideal micro conversions etc £24.95AMKEY MPNK-114 Superb word processorchassis keyboard on single PCB with 116keys. Many features such as On boardMicro, Single 5v rail full ASCII codedCharacter set with 31 function keys.Numeric keypad, cursor pad and 9600 baud
TTL ASCII OUTPUT]! ONLY£69.00 with data.
MMMMMM 11111111 au anonatoutaminanuantaxamati Emusodataulumumnamm am moosNNW omsMIM
Carriage on all Keyboards £3.50
PLESSEY VU TELManufactured byPLESSEY Ltd thiscompact unit, onlyslightly larger than a
\47,% 24 x40 character CRT
telephone. features anall in one TELEPHONE
screen. VIEWDATA-PRESTEL modem.
Keypad and electronics to run as a fullyfledged PRESTEL terminal or telephone.Ready to plug direct into a BT 600 type jacksocket and instantly connect you toPRESTEL etc Many other features includeMemory dialling. Recall button, Off line screendata storage. Picture expand, StandardMultard LUCY chip set Integral JVC crtmonitor. etc etc Designed to sell to theEXECUTIVE at over £600f! But fromDISPLAY. BRAND NEW AND BOXED atonly (9900 for DTMF tone dial or £140.00for standard DIAL PULSE version.Carr. t8_00.
PRINTER / TERMINAL SCOOPA MASSIVE purchase of these attractive stand aloneterminal units enables a SUPER BARGAIN offer. Made bythe US GENERAL ELECTRIC CORPORATION the GEMODEL 30 features a standard OWERTY 80 keyelectronic keyboard coupled to a quality built matrixprinter with variable 3' to 9.5" forms tractor. The printer iscapable of continuous duty printing with up to 120characters per tine Standard RS232 interface acceptsASCII data at 110. 150 or 300 baud. Ideal for Terminals.Data loNers, local label printing. or just as a printer!! SoldTESTED with data ONLY £95.00. Also available withTWIN MAGTAPE CASSETTE unit for data capture, datapreparation etc £150.00 Carriage (10.00.
COLOUR AND MONOCHROMEMONITOR SPECIALS
`SYSTEM ALPHA' 14" COLOUR MULTI INPUT MONITORmade in the UK by the famous REDIFFUSION Co. for their own professorialcomputer system this monitor has all the features to suit your immediate andfuture monitor requirements. Two video inputs: RGB and PAL Composite Video,allow direct connection to the BBC and most other makes of micro computersand VCR's. An internal speaker and audio amplifier may be connected to yoursystems output or direct to a VCR machine, giving superior sound quality. Manyother features included PIL tube, Matching BBC case colour. Major controls onfront panel. Separate Contrast and Brightness- even in RGB mode, Two types ofaudio input, Separate Colour and audio controls for Composite Video input, BNCplug for composite input, 15 way 'D' plug for RGB input modular constructionetc etc
This Must be ONE OF THE YEAR'S BEST BUYSSupplied BRAND NEW and BOXED, complete with DATA and 90 day guarantee_
SUPPLIED BELOW ACTUAL COST- ONLY £149.00
DECCA 80 16" COLOUR monitor. RGB inputLittle or hardly used manufacturer's surplus enables us to offer this specialconverted DECCA RGB Colour Video IV Monitor at a super low price of only£99.00, a price for a colour monitor as yet unheard oft Our own interface, safetymodification and special 16" high definition PIL tube, coupted with the tried andtested DECCA 80 series TV chassis gives 80 column definition and picturequality found only on monitors costing 3 TIMES OUR PRICE In fact, WEGUARANTEE you will be delighted with this product the quality for the price,has to be seen to be believed. Supplied complete and ready to plug direct to aBBC MICRO computer or any other system with a TTL RGB output Otherfeatures are: internal speaker, Modular construction, auto degaussing circuitAttractive TEAK CASE, compact dimensions only 52cm W x 34 II x 24 DI, 90 dayguarantee Although used. units are supplied in EXCELLENT condition. ONLY£99.00 + Carr.DECCA 80 16" COLOUR monitor. Compositve video input Same as abovemodelVCR or AUDIO VISUAL use ONLY £99.00 + Carr.REDIFFUSION MARK 3, 20' Colour monitor. Fitted with standard 75 ohmcomposite video input and sound amp This large screen colour display is idealfor shops, schools, clubs and other AUDIO VISUAL applications. Supplied in ASNEW or little used condition ONLY £145.00 + Carr.BUDGET RANGE EX EQUIPMENT MONOCHROME videomonitors.All units are fully cased and set for 240v standard working with composite videoinputs Units are pre tested and set up for 80 column use on BBC micro etc Evenwhen MINOR screen burns exist- normal data displays are unaffected12- KGM 320-1 B/W high bandwidth input, will display up to 132 x 25 lines.
ii4REEN SCREEN version of KGM 320-1 Only £39.959' KGM 324 GREEN SCREEN fully cased very compact unit Only £55.009 HITACHI V164-908E/K Black and White screen £49.95
Carriage and insurance on all monitors £10.00
Lt. C. POWER SUPPLY SFCIALSGOULD OF443 enobsect compact sw:tch mode suopty 5,th reg Wed outputs of+5v 6 5.5a. +12, ' 0.5a -I2v 6 al a and -23v ..7, 0.02a 13.m la x ti x6 cm 110 or240v input. BRAND"NEW only £14.95GOULD 06-404 5v 40 amp switch mode supply NEW £13000GREENDALE 19A-BOE Switch mode 60 watt open PCB with a fully regulated DCoutput of 5v 6 6 amps and three semi regulated outputs of +12V, -12V +15V 6 upto 1
Din only 11 cm x 20 cm x 5.5 cm. Similar to Hs 591-994. 110 or 240v AC inputTESTED es ectu_ 4iment Onty £24.95AC -DC Linear PSU for DISK drive and SYSTEM applications Constructed on a ruggedALLOY chassis to continuously supply fully regulated DC outputs of +5V 6 3 amps -5VSi 0.6 amps and +24v Si 5 amps Short circuit and overvoltage protected Ito or 240 VAC input Dim 28 x 12.5 x7 cm NEW £49.95.
Carriage an PSI.fs £200
SPECIAL 300 BAUD MODEM OFFERAnother GIGANTIC purchase of these EX BRITISH TELECOM. BRANDNEW or little used 2B data modems allows US to make the FINALREDUCTION. and for YOU to loin the exciting world of datacommunications at an UNHEARD OF PRICE OF ONLY £29.95. Made tothe highest POST OFFICE APPROVED spec at a cost of hundreds ofpounds each, the 2B has all the standard requirements for data base.business or hobby communications. All this and more!! 300 baud full duplex CALL ANSWER and AUTO modes Full remote control ;sae' 4401' Standard RS232 serial raterrace CCITT tone standards NOW OWL- Built in test switching Supplied with full data p9.95 k 240v Mains operation Modular construction -A. A. *Poe. 1 year full guarantee Direct isolated connection . Y.. Just 2 wires to comms line
BT 600 Jack plug and cable £2.25 Carriage and Ins. £10.00
YOU TERMINALSStandard VDU data entry terminals at grve awaypricest7OUME OVT108. Current product state of the artterminal with detachable keyboard 12- greenscreen 2 Rage RAM, TVI 925 emulation. 25 x 80.GIG,* Swivel and tilt base, Printer port Functionkeys etc BRAND NEW and BOXED AT ALMOSTHALF PRICE Onty £425.00A.1510 - EX RENTAL Z80 controlled. 1s,'green screen 24 x 80 display, graphics. CLItiOraddressing. printer port etc Very good conditionTESTED complete with manual only £225.00.ADDS 520 -Dumblerminal used 12" b/w screenRS232 interlace and printer port. TESTED.ONLY £125.00
Carnage on terminats £10.00loos Cf other terminals in stock
CALL for more detail.
All prices quoted are for U.K Mainland paid cash with order in Pounds Sterling PLUS VAT. Minimum order value ELOO.?... in 'mum C red it Ca rd order e/ 0.00.Minimum BONA FIDE account orders from Government Depts.Schools. Universities andestablished companiesE20.00.Where post and packing not indicated please ADD £1.00 + VAT. Warehouse open Mon -Fri9 30-530. Sat 10.30.5 30. We reserve the right to change prices and specifications without notice Trade. Bulk and Export
3 lIrr Ai I rif 32 Biggin Way, Upper Norwood, London SE19 3XF._ _ri I N U / IS! -1- Telephone 01-679 4414 Telex 894502 Data 01-679 1888 14.]
Lowest possible prices?
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Pick up a copy of our new 1986 catalogue from any branch ofW.H. Smith for just £1.45.Or post this coupon now, to receive your copy by post for just£1.45 + 40p p & p. If you live outside the U.K. send £2.50 or11 International Reply Coupons. I enclose 11.85.
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MAPLIN ELECTRONIC SUPPLIES LTD.Ma Order. P.O. Box 3. Rayleigh. F<cx SS6 8LR.Telephone: Southend (0702) 552911
SHOPS BIRMINGHAM Lynton Square, Perry Barr, Tel: 021-356 7292. LONDON 159-161 King Street, Hammersmith, W6.
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