Electric Bells and Alarms

H OW TO INSTALL

Electric Bells, Annunciators,

and Alarms.

lNCLUD lNG

Batteries , Wire s and Wiring, C ircu its , Pus/zes,Be lls

,

Burglar A larms , H iglz arid L ow Wa te r A larms,

Fire A larms , Tit e rmostats , A nnuncia tors ,

and til e L oca tion and Remedying

of Troubles.

NORMAN H .

‘S'CH NE

'

IDERAuth or of “ Th e Study of Ele ctricity fo r Beginne rs, Care and

H andling of Ele ctric Plants," e tc . , e tc.

SECONQ fidmomfismmééb

NEW YORK

SPON CH AMBERLAIN . 123 LIBERTY STREET

LONDON

E. F. N . SPON . Limited, 57 HAYMARKET. SW.

1913

Copyright 1904

Copyrigh t 1913

By SPON 8c CHAMBERLAIN

The Came lo t Pre ss , 16-18 Oak St N ew

PREFACE

Among all the applications o f electric ity todomestic or commercial uses, few are as w idespread as the electric bell . Practical ly every building used for a dwell ing

,storage or manufacture

requires an electric bel l,annunciator or alarm

system .

This book was wr itten to explain in practicallanguage how an electric b el l system operates and

h ow it is installed ; its success shown Iby its largesale has resulted in this new edition which bringsthe subject up to date .

M any new diagrams of annunc iator and burglaralarm systems have been added

,together with de

scriptions and i llustrations of w iring elevato rs forelectric “bells

,w iring for door o peners , th e use of

trans formers for furnishing suitable ringing current from electric l ight c ircuits ;and high voltagebells intended to be used on other than the customary low voltage battery ci rcuits .

Th e author expresses his acknow ledgment to theWestern Electric Company for diagrams of

'

dooropener c ircuits in connection w ith thei r interphonesystems , to Edwards and Company of N ew Yorkfo r diagrams of fire alarms

,

v

burglar alarms and

annunciato rs , and to the Westinghouse Companyfo r i l lustrations of bell - ringing transfo rmers .

2 674 9 4

CONTENTS

I N TRODUCTI ON

Introduction . Th e princip le of an e lectric be ll .

CH APTER I

Th e L e clanch e ce l l— Polari z ation— Se tting up—Th e

dry ce l l—Th e grav ity ce l l—Connect ing up ce l ls

CH APTER I I

Th e singl e strok e / be ll—Th e shunt be l l—Th e different ial be l l—Th e continuous ring be l l—Th e waterproof be l l—Forms of gongs—Th e buz z er— L ongdistance be l ls—Th e re lay—Th e push—Three pointor double contact push—Floor push—Door pul lIndicat ing push

CH APTER I I I

Be l l w ires- Joints—Runn ing w ire s—H ow to put up a

door be l l—Comb inations of be l ls, pushe s and bat

terie s—Faults in be l ls, faults in w iring—H ow to_

locate and remedy faults

Vi CON TEN TS

CH APTER I V

PAGE

Fire alarms—Thermostats—Me tal l ic thermostats—M er

cury th ermostat— H ow to connect th ermostatsWate r leve l indicators—Burglar alarms— Op en and

cl osed circu it alarms—Window ,door and shade

springs— Alarm matting—Yale l ock alarm—D 0 0trip alarm

CH APTER V

Th e annunciator drop—Th e ne edle or arrow dropTh e pendulum drop—Wiring up annunciatorsReturn or fire cal l systems—Double w ire systemWestern Electric sing le w ire system 55

CH APTER V I

Thre e -wire return cal l system— Instal l ing e l evator an

nunciators— Burglar alarm annunciators— Clockalarm circuit— Be l ls for high voltages—Be l l—ringingtransformers— Combinat ion be l l , door Op ener and

te lephone c ircu its—Fire alarm circuit— interior firealarm system— Fire alarm system for considerabl eareas

LI ST OF I LLUSTRATI ON S

Fro .

1 '

Electric be l l , push , and battery2 L eclanch e ce l l3 Dry ce l l4 Grav ity ce l l5 V ibrat ing be l l6 Single strok e be l l7 Shunt or short circuit be l l8 Continuous ring be l l9 Waterproof be l l10 Dome gong1 1 Tea gong12 Cow gong13 Sle igh be l l gong14 Sp iral gong

Re lay and circuit16 Door push17 Pear push18 Door push19 Wal l push20 Fl oor push2 1 Door pul l attachment

22 Wire joint first operation23 Wire joint second Operation24 Wire jo int insulating25 Section Of house show ing wiring26 Be l l w ith ground re turn27 Pushes in multip le

viii L I ST OF ILLUSTRATION S

FI G .

28 Be l ls in series29 Be l ls in mult ip le30 Two be l ls and two pushes3 1 Two be l ls and two pushe s32 Two be l ls, two pushes and one battery33 Double contact push34 Grounded be l l35 Tongue test of w iring36 . Kn i fe te st Of w iring37 Kn i fe te st of w iring38 M e tal l ic thermostat39 M ercury thermostat40 M ercury thermostat Circu it4 1 Wate r leve l alarm42 L eve r wate r leve l alarm43 H igh or low wate r leve l alarm44 Window spring for burglar alarm45 Burglar alarm— cl osed circu it46 Special be l l connect ion for burglar alarm47 Special be l l connect ion for burglar alarm48 Burglar alarm and re lay49 Window - shade contact spring50 House w ired for burglar alarm51 Door trip alarm52 Annunciator drop53 N e edle drop54 N eedle drop indicating55 Pendulum drop56 Annunciator drop circuit5 7 Simp le annunciator circu it58 Annunciator and fire cal l circu it59 Single -wire room and fire cal l

~FI G.

60

61

62

63

64

65

66

67

68

69

70

L I ST OF I L LUSTRATI ON S

Th re e -w ire re turn cal l circuitElevator be l ls and annunciator c ircuit .

Burglar alarm annunciator circu it .

’

Clock alarm circuitBe l l - ringing transformerBe l l- ringing transformer w ith three secondaryvoltagesWestern Ele ctric interphone systemWestern Ele ctric interphone system for more ex

tensive serv iceFire alarm circu itInterior fire alarm circu itFire alarm circu it for considerab le areas

INTRODUCTION

An electric bel l depends for its action on the

fact that a piece Of i ron wound with insulated

w ire becomes a magnet and wi l l attract anotherpiece of i ron j ust so long as an electric current is

allowed to travel through the w i re .

Th e instant the current ceases,the magneti sm

al so ceases,and the attracted piece of iron ( termed

the armature ) i s no longer held in contact .

Th e general construction of an electric bel l

i s shown in Fig. 1 . M M are coi l s of'

insulated

wire wound on soft i ron cores . A i s a soft i ron

armature mounted on a flat spring so that h is

normally kept a sl ight di stance away from the

soft i ron cores . 5 i s a brass screw with a plat

inum tip touching a platinum disc on a spring

attached to the armature .

When the push button P i s pressed down . i ts

two brass springs touch each other,the current

from the battery cel l B then flows through the

w ire W, through the push P , through the

co i l s M M , along A to the platinum disc, out

IN TRODUCTION

FI G. 1

IN TRODUCTION

at S , wh ich touches thi s di sc , and back to th e

battery .

The instant th i s i s done the current causes the

iron cores to become magnets,they attract A

,

which then breaks contact at S . The spring

mounting of A causes i t to j ump back to its

first position , 5 then touches the platinum disc

again , the current fiows as before , and the arma

ture i s again attracted only to break contact

with S and fly back .

Thi s continual making and breaking Of the

Ci rcuit keeps up as long as the push i s pressed,a

bal l mounted on A by'

means Of a rod strikes

against the gong G causing a continuous ringing

of the bel l . The wires leading between the bell ,battery cel l and

'

push must al l be insulated,that

is, covered with cotton ,rubbe r

,etc .

,which pre

vents the leakage of current should two wires

cross each other . Copper w i re i s mostly used for

ci rcuits indoors,the detai l s of the k ind and size

Ofw ire wi l l be given later on .

‘

Th e main parts of an electric bel l Ci rcuit are

then— the battery to supply the electric current ;the ci rcuit

,or wires

,to carry thi s current ;a push ,

or c ircuit breaker,to control the current flow ;

and a bell to ut i l ize the current .

CH APTER I

Th e Battery

Th e Battery Ce l l . The battery cel l most used

in electric bel l work i s the L eclanch e , or some

modification of it .

The L eclanch e battery cel l is shown in Fig. 2 ,

4

FI G. 2

where J is a glass j ar,Z a rod Ofz inc

,and P a j ar

Of porous earthenware conta ining a carbon rod

surrounded by powdered carbon and perox ide Of

manganese .

“ ELECTRIC ‘BELLS AN D ALARMS

In setting up thi s cel l about four ounces of

sal ammoniac (chloride of ammonia ) are put into

the jar and enough water added to come about

hal f way up the j ar .

Th e porous j ar P and the z inc Z are then

inserted , and the cel l i s ready for use in a few

minutes after the l iquid has soaked through the

earthenware into the carbon -manganese mixture .

Water i s often poured into the porous j ar throughholes in its top to hasten thi s wetting .

Wi res are clamped by nuts or set- screws to thenegative terminal on the z inc or the positive ter

minal on the carbon,i t general ly not being of

consequence which term inal i s attached to either

wire of the circuit .

A battery cell could be constructed without the

manganese,using simply a plate Of carbon and

a rod Of z inc,but hydrogen gas would be gen

crated on the carbon plate when th e cel l was work

ing and would stop the current flowing .

This i s called polarization,and perox ide of man

ganese i s a de- polarizer,because it combines with

thi s hydrogen gas almost as fast as i t i s generated ,

and prevents,to a great extent , the polarization .

But i t does not stop it entirely , as wi l l be seen

i f the L eclanch e cel l i s kept working above its

capacity . Then the hydrogen i s generated too

fast for the manganese to destroy it , and the cel l

TH E BATTERY 3

ceases to work . In thi s case a rest wi l l often

restore the cel l to its former power .

Cel ls which have been almost unable to make

a bel l g ive even a sing le tap have been found

good again when al lowed to remain at rest over

night .

In setting up a batterycel l no l iquid should besplashed on the brass terniinals or corrosion wi l ltake place . Every metal surface where connec

tion is made to al low electric current to passmustbe clean and bright

, and al l screws , or nuts , hold

ing wires must be screwed up tight so that thewires are firmlygclamped .

L oose or dirty connections are the cause Of

probably eight out of every ten troubles affecting

bel l s and batteries .

When the fluid in'

a L eclanch e cel l becomes

milky , more sal ammoniac must be added . Or,

better sti l l,throw out the Old solution ,

wash the

porous j ar thoroughly I n Clean water , scrape the

z inc bright,and hal f fil l the cel l w ith fresh solu

tion .

The z inc wearing away rapidly or becoming

covered with crystal s,and a strong smell of am

monia,show generally that the cel l i s being worked

too hard,or that the current i s leaking where it

should not .

A z inc rod in a cel l working the average door

4 ELECTRIC BELLS AN D ALARMS

be ll should last for six months , the porous j ar for

a year .

Th e Dry Ce l l . The L eclanch e cel l being a

cel l with much free l iquid i s l iable to dry up i f

not watched . The dry cel l (Fig. 3 ) i s a modern

FI G. 3

form of the L eclanch e where the l iquid is held by

an absorbent material,such as blotting paper, or

plaster .

A typical dry cel l* i s shown in the figure . An

*For ful l description Of this class Of battery see N o . 3

Book on“

Dry Batteries.

"

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6, ELECTRI C BELLS AN D ALARMS

~Th e Gravi ty Danie ll Ce l l . The gravitvcell ,Fig. 4

,has a zinc block Z suspended from the

s ide of the j ar and a number Of copper leaves C

standing on edge at the bottom . A quantity of

bluestone ( sulphate of copper ) i s poured over th e

copper leaves and the j ar fil led w i th water .

During the working of thi s cell,copper is de

posited on the copper plate,and sulphate of zinc

formed at th e z inc . TO hasten the action a smal l

quantity of z inc sulphate can be added to the

solution when setting up the cel l .

Th e name "of thi s Cel l comes from the fact that

th e e ofiper solution being heavie r rema ins at thebottom of the j ar . I f the cel l i s not worked

enough ,al l the solution will become blue and th e

z inc wi l l blacken . I f “ very di'rty'

from th i s cause ,remove the z inc

,scrape and wash it thoroughly .

Th row out al l the solution,add new sulphate and

water and replacing the z inc, then put the cel l

on short ci rcuit by' connecting the copper and

z inc together for a few hours .

B. M . F. Th e e . m . f . Ofa grav ity cel l is w ith in

a fraction of one volt,i ts current nearly one- half

N Varm'

th amak es i t give a greater current ;on

no account let a grav ity cel l freeze .

TH E BATTERY 7

Re sistance ofa Ce l l . The flu ids in a cel l do

not conduct electricity as well as copper do es ;they

offer more resistance and thus . reduce the current

output .

Th e internal resi stance Of.a cel l may be low

ered by using large z inc plates curled around the

porous pot .

Th e Samson cel l has a large z inc plate bent in

the form of a cyl inder,the carbon -manganese

combination standing in the centre Of it .

The dry cel l al so has a large z inc , the internal

resistance being thus much lowered , the current

output i s increased . This i s by reason OfOhm’s

law,which teaches that to increase the current

flow , either the voltage of the battery must be in

creased , or the res istance decreased .

But increased current means lessened l i fe ;there

i s only just SO much energy in a cel l ma inly de

pendent ou the quantity of chemicals .

G rouping OfCe l ls. Cel l s may be grouped in a

battery to get increased voltage,or increased am

perage . When connected for the former,they

are in series , the carbon Ofone i s connected to the

z inc of the next,and so on .

I f all the carbons are connected together and al l

the z incs , they are in multip le, and w i l l give the


same voltage as of one cel l but the comb ined am

perage Of al l .

In ordinary bel l work the series i s the general

connection,the higher the resi stance Of the ci r

cuit, or the longer the wires , the more voltage is

requ ired .

CH APTER -I I

Bells and Push es

E le ctricBe l ls. Th e two ma in types of house

bel ls are the i ron box and the skeleton .

Th e i ron box has a cast- i ron frame , or base, and

a cast or stamped- i ron cover over the mechanism .

The skeleton bel l has an iron frame but no

cover,and i s general ly better fini shed and more

expensive than the i ron box bel ls .

For fire alarm purposes,mechanical bel ls or

gongs are made,in which a clockwork mechan

i sm causes the hammer to strike the gong upon

being re leased by electromagneti sm .

M arine or waterproof bell s have an iron cover

fitting tight over a rubber gasket ; they are for

marine,or mining, work .

Polarized , or magneto , bel l s are used in tele

phone work , and are rarely Operated by a battery ,but have a min iature dynamo generator operated

by hand , or power, to supply the actuating cur

rent .

M ost bel l s are classed for s ize by the d iameter

of the gong, a four—inch bel l being one with a

gong four inches in diameter ;a six- inch bel l one

with a six-inch gong,and so on .


According to the use for which they are in

tended , bell s may be vibrating,as before described

,

s ingle- stroke,shunt or short- ci rcuiting

,differen

tial , continuous - ring ing,or adapted for ci rcuits Of

high voltage .

Th e S ingle -strok e Be l l . Th e bel l before de

scribed , and again shown in Fig. 5,i s a vibrating

,

or trembl ing,bel l . It is often des ired to have the

hammer give only one stroke for each pressure of

the push,as -in signaling with a code of taps ;in

thi s case a single- stroke bel l is used . The ci rcuit

FI G. 5 FI G. 6 FI G. 7

from the binding posts i s then directly through

the magnet coi l s without any break at the contact

screw,as in Fig. 6 .

I n adjusting such a bel l to give a clear sound ,

press the armature up against the i ron magnet

cores and then bend back the hammer unti l i t j ust

clears the gong . The spring of the hammer wire

wi l l carry the hammer suffic iently forward to hi t

the gong . The tone w i l l be clearer than i f the

hammer dampered the gong by press ing against

it when the armature was nearest the core .

BELLS " A N D PUS H E-s I t

By br ing ing Out a thi rd connect ion ,avibrating

b'ell may be made both single strok e and vibrating.

Th e S h unt Be l l . There i s a form of bell

Fig. 7 -known as th e shunt,or short circuit

"

bell ,which isO ften

“

used when two or more are to be

connected in series,as w i l l be seen in the descrip

tionof ci rcuits . In thi s “ bel l the ci rcui t through

the magnets i s not broken at the contact screw,

but the forward movement Ofth e ia‘

rmature short

ci rcuits the coi l s .

"

As

‘

th e'

short,or shunt

,Circuit i s very

‘

much

lower in resi stance than'

the w i re on the magne tcoi l s

,th emain current flows around t h e latter and

they do not become ene rg i zed . Th e spark ingfat

the shunting contact screw is much less than it

would be at the ordinary breaking contact screw ,

and the platinum points last longer .

Th e Diffe re ntial Be l l .“

Sparking at th e break

ing contacts Of an electri c bel l i s detrimental “ to

the platinum points , and many remedi es have beendevi sed to overcome it .

Sparking IS due to the selfiin‘

duction Of"

one

turn Of the wire coi l acting on its

th i s property i s uti l i zed in the gas engine, . -orL gBS;

l ighting spark coil , wh erea fat spark is needed .to

ign ite gas .

ELECTRIC BELLS AN D ALARM S

The differential bel l has two windings in oppo

site di rections . The action of one would be to

produce an N - pole at one end and an S- pole at

the other . But the second coi l produces poles j ust

the opposite, as the polarity Ofa magnet depends

on the di rection in wh ich the current flows around

it .

Where the current flows around the first winding the armature i s attracted and its spring con

tact meets the contact screw and al lows the cur

rent to div ide , part flow ing through the first coi l ,the other flowing in the reverse direction in the

Oppos ite way . One coi l would tend to produce

anN - pole where the other co i l produced an S-

pOle ,and these Oppos ite poles would so neutral ize each

other that there would be no magneti sm .

Th e armature would therefore be pulled back

by its Spring when both coi l s were thrown into

c ircu it . In so do ing it would cut out one co i l

and the same ser ies of Operations would recom

mence .

As a spark is normal ly produced where mag

netism is lost by a break Ofci rcu it ,* no spark ap

pears , as magnet ism i s produced by a break of

Circu it in th i s case .

*For a full exp lanation Of se l f- induction see N O . I of

this series.

1 4 ELECTRIC BELLS A N D ALARMS

to A,thence through L and S ,

’

to U and back

to B.

The bel l wi l l continue to ring unti l the spring

contact 5 i s moved back and caught by the pro

j ection on the armature A .

A continuous - ring attachment i s al so made and

sold in most electrical supply stores , which i s com

plete in itsel f and can be appl i ed to any bel l .

Waterproof Be l ls. In Fig. 9 i s an example Ofa waterproof bel l where the mechanism i s almost

al l ent irely encased in a waterproof brass case.

The ci rcuit is made and broken inside the Case ,but the magnet cores proj ect th rough

' it"

and act

on a second armature placed outs ide. Th is sec

ond armature carries the hammer which strikes

the gong and i s governed in speed by the contact

breaking armature inside .

BELLS AN D PU S H ES 1 5

Fo rms ofBe l l Gongs . In orderto prov ide a

variety o f sounds , bel l s are prov ided w ith gongs

Of various shapes .

‘

Fig. 1 0 shows the ordinary form Of gong .

FI G. 10 FI G . 1 1 FI G. 1 2 FI G. 13

Fig. 1 1 , a tea gong ;Fig. 1 2 , a cow gong ;and

Fig. 1 3,a sleigh bel l

A coi l Of steel W l l‘

e 18 also used,as in Fig. 14 ,

which on being struck by the hammer gives a

pleasant but not loud tone .

FI G. 14

Th e Buz z er. The buzzer i s the mechan ism of

a vibrating bel l less the hammer and gong . As

the armature vibrates it makes a buzz ing noi se

which does not carry as far as -the sound from

a struck gong . I t i s used chiefly for a desk cal l

1 6 ELECTRIC BELLS AN D ALARMS

and in telephone exchange work,or any p lace

where general attention i s not desired to the signal .

Op erating Be l ls at a Distance . When it i sdesired to ring a bel l situated at a considerable

distance from the push , the resistance Of the l ine

becomes Obj ectionable .

On l ines Of 500 feet, N O . 1 8 Copper w ire andupwards

,the battery necessary would be very

large, two small batteries and a relaywould prove

more sati s factory .

In Fig. 1 5 the ci rcu it of a simple form Of relay

i s given . An adju stable contact screw C i s placed

where an extension 5 Ofthe armature A can strike

BELLS AN D PU SH ES 17

it . Th i s extension i s prov ided w ith a platinum

contact . Th e connections are as in the figure .

When the push P i s depressed , the current fromthe main battery M energ i zes the electromagnet E

,

and the armature A being attracted , contacts 5

and C meet . These contacts Close the second c ir

cuit containing the bel l"

? and the local battery L .

The relay resembles a second push near the

bell , but control led by current from a di stance

instead Of being depressed by hand . Its advantage consists in it needing but a very weak cur

rent to move the armature A,which i s held back

by a l ight spring,or by grav i ty .

The relay may then be set near the bel l and

the wires from the push may be Of a very great

lengt h . Battery L,which actual ly rings the bel l ,

wil l thus only have to work through a few feet

Ofw ire .

Reducing Re sistance ofa Be l l . Sometimes

it is des ired to reduce the resi stance the bell coi ls

Offer to the current , the bel l then working over a

very short l ine with few cel ls Of battery . Or

the bel l coi l s may have been wound with fine

wire for large battery voltage and a long l ine .

The bel l co i l s may be put in multip le , the cur

rent then d iv iding and one- hal f going through

each spool .

1 8 ELECTRIC BELL S AN D ALARMS

U ntwi st the j oint between the spools near the

yoke or i ron bar to which the spools are attached .

Join one Ofthese ends to the wire at the armature

end Of the o th er spool and the second untw i sted

end to the armature end wire Of its neighboring

spool . U se short pieces Of insulated wire for

these extra connections .

The current now instead Of having to go

through one spool and then the other,can branch

through both at once .

The resi stance to the current Of one spool i s

hal f the resi stance Oftwo , the current through one

spool w i l l therefore be twice that through the

two spools as at first connected . And as there are

two paths for it,each one- hal f the first resi stance ,

the total wil l be only one—fourth the resi stance

Ofthe ordinary series arrangement .

The same size battery wi l l therefore send four

times . the current through the spool s in' multiple

than when they are in series .

It i s to be noted that the wire on one spool i s

wound in the reverse direction to that on the

other The reason w i l l be apparent i f the two

spools and yoke are considered as merely one

spool bent in a U or horseshoe form .

I f both spool s were wound in the same direc

t ion they would be in opposite directions when the

U were stra ightened out , and would cause l ike

BELLS AN D PU SH ES 1 9

poles at the same ends . These poles would neu

traliz e one another , so that there would be no

magnetic attraction .

This can be readi ly proved by j oining together

the two yoke ends and the two armature ends Of

the spool wires . Then pass the current through

these two j oined connections .

FI G. 16 FI G. 17 FI G. 18 FI G. 19

Th e PuSh Button . Push buttons,or pushes

,

are made in a variety Of forms , w ith metal , wood ,hard rubber

,or porcelain bases .

Fig. 1 6 has a metal base , and i s su itable for

a front door .

Fig. 17 i s a wooden pear push ,and is attached at

the end of a cord which has the two conductors

braided in it,each

,however

,hav ing its own in

sulation .

Fig. 1 8 i s a plate push for an outside


Fig. 1 9 i s either Ofmetal , wood , or porcela in ,and i s the shape most commonly used .

A three- point push has three contact springs .

One is movable by means Of the button,one i s

below the movable spring , and the thi rd is above

it .

push button is not being depressed

FI G. 20

the movable spring makes contact with the upper

spring . But when the button i s depressed,these

two springs part , and the movable spring makes

contact with the lower one .

This style Of push i s used for special bel l and

annunciator work,as wi l l be described later .

Th e form Ofcombination floor and table push in

Fig. 20 i s the most sol idly constructed device of

its k ind . Th e lower part i s set in a hole bored

in the flooring, the metal flange keep ing it in

p lace and prevent ing its sl ipp ing through .

22 ELECTRI C BELLS AN D ALARMS

be changed into an electric bell . Being screwed

up near the door pul l,a wire is run from the lat

ter and fastened to lever L . When the pull i sdrawn out the lever L turns on a pivot and a

proj ection presses the insulated spring 5 against

the metal base B. The circuit of the bel l and

battery being thus closed,the bel l rings .

FI G. 21

I ndicating Push Button . push button i s

made which contains in the base a smal l electro

magnet in series with the l ine . An armature on

a spring i s fixed near the magnet poles . Whenthe push i s depressed

,the current travels through

thi s electromagnet , and as the Circuit i s made

and broken at the di stant bel l,i t i s also interrupted

in the electromagnet . The armature v ibrates in

un i son with the bel l and thus gives an aud ible

indication that the bel l i s ringing .

CH APTER I I I

Wiring,Circuits and Troubles

Th e W i re . Th e s ize of the copper wire used

in bel l work i s N O . 1 6,or N O . 1 8

,B and S gauge ,

and sometimes smaller,such as N O . 20

"

to 22 .

But smal ler wire than N O . 1 8 has too much re

sistance,and would necessitate a larger battery

power,even i f i ts mechanical strengt h were not

too low . Th e insulating coverings are cotton satu

rated with paraffin wax or compounds .

Th e covered wires are variously known as an

nunciator, Office . or weatherproof wire , these terms

being mostly for di stinction Of the coverings and

not for the use to which the wire would be put .

Annunciator wire has two layers of cotton

merely wrapped around the copper and then satu

rated with paraffin .

Office wire has the two cotton layers braided ,

the Ins ide one being fil led with a moisture- repel

l ing compound .

Both Office and annunciator wires have thei routside coverings fi l l ed with paraffin and highly

pol i shed .

From the ease with which fannunciator wire i s

24 ELECTRIC BELLS AN D ALARM S

stripped Of i ts cotton covering,the braided Office

wire i s to be preferred . These coverings are made

in a variety Of. co lors.

Weatherproof covered w i re i s mostly used forelectri c l ight work , but the sizes g iven above are

good for bel l work,although their larger outside

diameter makes them harder to conceal .Th e approximate number Of feet to the pound

Of Office and annunc iator wire i s g iven in the

table .

Oflice Wire . Annunciator Wire .

Fe e t pe r 1b . Fe e t pe r lb .

Jo ints. U pon the care with which a j oint i s

made much depends,a loose or poorly made joint

wi l l Offer much resi stance to the current .

Th e correct way to start a j oint in annunc iator ,or Office

,wire i s shown in Fig. 22 . About three

inches Of each wire to be joined i s bared Of i ts

insulation and scraped bright . The ends are then

W IRIN G,CIRCUITS AN D TROU BLES 25

bent at right ang les to each other,hooked together

and one end firmly twisted around the other,as

shown in Fig. 23 . Any proj ecting pieces are cut

Off, and the joints should then be soldered to pre

vent corrosion .

FI G. 23

FI G. 24

Adhesive tape friction tape is wrapped

around the j oint , Fig. 24,and pressed firmly to

gether so that there i s no chance Ofi ts unravel l ing .

Th e tape wrapping Should extend across the j oint

and on to about a hal f inch Of the insulation

around each w ire .

26‘

ELECTRI C BELLS AN D ALARMS

Running th e W i res . TO detai l al l the opera

tions Of instal l ing a complex system of bell,alarm

and annunciator w i res would be impossible from

the reasons that conditions vary and space i s l im

ited. General d irections w i l l then only be g iven

to enable the inexperienced to run such w i res as

may be needed in ordinary domesti c work and to

guard against the most common causes Offai lure .

Wi res may be run in tin tubes to prevent thedepredations Ofrats and mice , or theymay be runwith simply their own covering for protection ;i t

i s presumed the latter i s undertaken .

In a case where the building is Of frame and

in course Of erection th e task i s much simplified.

H av ing first decided upon th e plan ,number Of

bell s , pushes , etc . and the ir locat ion ,proceed to

run the wires first in order that the pushes,bel l s ,

etc . may not be injured .

But where the house i s al ready occupied , as in

the majority of cases l ikely to be met with by th e

reader,th e bel l and battery may be set first .

Take the case Ofan ordinary door bel l w ith th e

push at the front door,the bel l in the kitchen and

the battery in the cellar . I f possible get the wire

on two spool s ; i t w i l l s impl i fy matters i f both

w i res are Ofdifferent colors . Starting at th e push .

have a foot Ofeach w ire for connect ion and slack ,

and fasten each w ire l ightly to the woodwork w ith

W IRIN G, CIRCU ITS AN D TROU BL ES 27

staples,or double-pointed tacks , never putting two

wires under one staple nor driv ing in a staple SO

i t cuts the insulation . Some cases wil l require a

staple about every foot, on straight runs some

times every three feet .

In many Cases the wires can be partly con

cealed in the angle between a moulding and thewall , or even in a groove Of the moulding i tsel f .

When running along a ski rting ,the w i res may

O ften be push edi

out Of s ight between it and the

floor . DO not attempt to draw the wires too

tight or the changes of the weather may break the

wires when the woodwork shrinks or swell s .

The wires wi l l be,one from the push to the

bel l,one from the push to the battery , and one

from the bel l to the battery . SO i t i s probable

that the second wire can be run r ight through a

Smal l hole bored in the flooring under the push ,

but inside the front door . In thi s case it wi ll

be perhaps easier i f the spool be left in the cellar

and the end Ofthe wire be pushed up from below

and stapled to the woodwork near the push , leav

ing the cel lar work to the last . Only one wire

wil l be run then direct to the bel l upstairs and

it can be better concealed than two .

I f necessary it may be drawn under a carpet

and not stapled,or it can Often be forced into the

crack between two boards . But if not , run i t


along the Skirting,fo llowmg the wal ls unti l i t

reaches below the bel l . I t i s O ften better to go

ent irely around a room than to cross below a

door .

I f a door must be crossed the wire may either

run up one Side Of the frame and down the other'

Or laid beneath the carpet on the Si ll . The former

i s preferable, but takes more wire .

In many houses the bel l wire as wel l as the bat

te ry wire may be run across the cellar beams

(Fig. in which case bore a second hole for it

near the push ;do not draw it through the same

hole as the push to battery wire . And,Ofcourse,

here work upwards with the Spool in the cel lar .

H av ing reached the bel l location, run the third

wire down into the cel lar to the battery . N ow

connect up the push,baringan inch or SO Of each

wire,push them through the holes prov ided in

the push base,screw down the push base and

clamp the w ires under the washers through which

the connect ion screws run . DO th is neatly , be sure

the ends Of the w ires do not stick out , cut Off

what i s left free Of the bared ends . Th en con

nect the battery to the wire from the push and the

wire from the bel l . The last thing is to scrape

and fasten the bel l w ires to the bel l bind ing posts .

DO th is SO that they cannot come loose and that

they make good contact .

ELECTRIC BELLS AN D ALARMS

The bel l should now ring properly when the

push i s pressed .

To sum up , one w i re leads from one spring

Of the push to the bel l , one wire from the oth er

spring Ofthe push to the battery,and another wi re

from the remaining binding post on the bel l to the

remaining binding post on the battery . It i s im

material whether the zinc terminal or the carbon

terminal go to the bel l or push .

Comb inations OfBe l ls andPush e s . One of

the wires in a bel l Ci rcuit may be replaced by

the ground (Fig. Connection may be made

to a gas or water pipe or to a metal plate buri ed

deep in damp earth . Any wire fastened to such a

FI G. 26

plate must be thoroughly soldered to it or a voltaic

action wil l be set up , which will eat it away at the

point of contact .

When one bell is to be rung from two or

more po ints th e pushes are to be connected in

W IRIN G,CIRCUITS AN D TROUBLES 31

multiple (Fig. 27 ) as i f they were in series ;al l

would have to be closed to complete the circuit .

I f two bells are to be operated from one push

FI G. 27

they may be in series (Fig. but in th i s case

one Of them must be arranged for S ingle stroke .

FI G. 28

I f both were v ibrating bel ls the armature Of one

would not y ibrate in un ison w ith the other arma

FI G. 29

ture and the result would be i rregular contact

breaking and intermittent ringing .

A preferable connect ion for two or more bel l s


and one push i s Fig. 29,where the bel l s are in

multiple . Thi s requires more current than the

series method .

FI G. 30

To ring two bell s from either one Oftwo points

the arrangement in Fig 30 Wil l answer . It re

quires only two wires or one Wire and ground

return,but two batteries . AS both bel ls are in

FI G. 31

multiple both wil l ring, the one nearest the push

being depressed ringing the loudest . This IS a di s

advantage . I f the series arrangement in Fig, 31

W IRIN G,CIRCUITS AN D TROUBLES 33

be Selected one bel l must be arranged for Singl e

stroke . Both bel ls wil l ring with equal power .

In Fig. 32 only the distant bel l rings , the Cir

FI G. 32

cuit hav ing only one battery but three w ires,or

two Wires and ground return .

A plan where two batteri es are needed but on ly

two wires,or one wire and ground i s in Fig. 33 .

Double contact or three- point pushes are necessary

FI G. 33

here , making one contact when depressed and a

second one when not being touched .

In thi s figure only the di stant bel l rings .


Fau lts inBe l ls . On examining many electric

bell s i t w i l l be noted that only one binding post

i s in sulated from the frame when the latter i s

Of. iron (Fig. As the armature spring 5 in

electrical connection with the frame F by reason

Of i ts metal screws and support,the Ci rcuit may

run from the insulated post U to the magnet coil s ,thence through the insulated contact screw C

through the armature spring (wh en it i s making

contact ) and through th e frame to the uninsulated

post I

This saves labor,wire and compl icat ion , but i f

th e insulation Ofthe post U,the w i res W V

, or the

contact screw C be injured , the current may take

a short path back to the frame .

I f C were thus grounded ,the bell would act as

a Single- stroke bell .

I f U were grounded,the bel l would not ring

W IRIN G,CIRCU ITS AN D TROUBLES 35

at all , as that would be a short ci rcuit on the bat

tery between I and U and the latter would al so

result i f the bare wire were touching the frame

at V .

I f the bare w i re touched the frame beyond M M

that is,along W

,i t would be a Single- stroke bell

,

as i f C were grounded;

AS any one of these faults i s l ikely to occur

they should be looked for when the bel l acts im

perfectly,Or not at al l .

A very common fault in a bel l i s when its arma

ture sticks to the cores and thus does not make

contact w i th the contact Screw . This may be from.

a weak spring or because Of the loss Of the pieces

of brass inserted in the ends Of the cores to keep

the armature away from actual contact . A piece

Of a postage stamp stuck over the core end wil l

O ften help out in the latter case .

A high SCreech ing no ise from the armature v i

brating too rapidly but with too l ittl e play , may

be from excess ive battery power or the contact

screw being too far forward . Th e former wil l

general ly be detected by the v iolent sparking as

wel l as the rapid vibration .

In very cheap bell s the platinum contacts may

be replaced by German Si lver or some other metal .

Platinum is necessary because the Sparking

would soon corrode other metal s,but it i s very


expensive . TO test for platinum put a tiny drop

Of nitri c acid on the suspected metal . I f bubbles

or smoke appear it i s not platinum . After apply

ing thi s test in any case however,careful ly wash

Offand remove al l traces of the acid,as it Wi l l cor

rode the metal into which the platinum is riveted .

D i rty contacts wi l l decrease the current in the

bel l coi l s and it wi l l not work well,i f at al l .

L oose contact screws and Wires al so give

trouble . Th e adjusting Of the contact screw i s Of

the utmost importance,and should never be at

tempted unless it i s clearly necessary .

Fau lts in L ine . In looking for a fault in a

bell ci rcuit make sure the battery i s work ing;i f

Only one or two cel l s,put the ends of two w ires

attached to the terminal s on the tongue "a metal l ic

taste W i l l indicate current .

Then see that the Ci rcu it‘

w ires are firmly

clamped in the terminal s and no dirt or corrosion

on the connections .

Next examine the push button and see that the

wi re connections at the Springs are perfect .

I f there i s no movement Of the bell at al l when

the push i s pressed in,take a pocket kni fe or

screw driver,and touch the blade across the push

Springs . I f there i s current flowing sparks wi l l

be seen when the blade breaks contact between


current wi l l travel from the battery to the cross

at S,then back along the second circuit wire to

the tongue and through the Short wire to the

battery .

FI G. 35

I f no current is Obta ined in th is way i t i s prob

able that the Wire is broken .

FI G. 36

The eas iest way to find t hi s i s to take a bell

to the battery and connect i t between the c ircuit

wires and the battery (Fig.

Then w ith a Sharp kni fe careful ly cut away a

W IRIN G, CIRCUITS AN D TROUBLES 39

l ittle piece Ofthe insulation from each wire beyond

the bel l and battery and short circuit the bat ed

spots with the kni fe blade K . Keep working

towards the push . The bel l wi l l ring each time

at K K unti l the break D i s passed at C i t w i l l

no t. It becomes an easy matter then to locate

I t .

I f the bel l and push are far apart,as in Fig. 37,

a break between the push and the bel l may be

found as shown . With the kni fe blade K at different points the bel l wi l l ring

,but after pass ing the

break D it wi l l not ring .

Such Simple tests as are here given can be car

ried out by any one,but far better results wi l l be

Obtained i f the reason for each i s first l earned .

Thi s can be readily done by a careful study Of

the diagrams and text .

CH APTER I V

Alarms

Fire Alarms. Thermostats,heat alarms and

fire alarms are all practically the same,the term

thermostat being appl ied principal ly to the appa

ratus which closes the electrical Circuit .

FI G. 38

Thermostats act on the principle that heat causes

expansion whether Ofsubstance s,liquids

,or gases .

Th e degree in which different substances ex

pand vari es for the same increase in temperature .

Thi s fact i s used in a common form Of thermo

stat shown in Fig. 38 . A strip of wood or hard

rubber B has a strip of thin sheet metal 5 r iveted

to it . Th is compound strip i s held at one end,

by

ALARMS 4 1

a lug L screwed fast"

to a baseboard . U pon an

increase Of temperature the hard rubber expands

more than the metal strip and the compound str ip

bends towards“

the adjustable contact screw A .

U pon touch lng the latter , the ci rcui t through the

bell B,battery C and the metal strip 5 i s com

ple ted,and the bel l rings . A contact screw can

be arranged at the other Side OfS R,which wil l

give warning Ofa decrease in temperature,as the

rubber contracts more than themetal strip"I n some thermostats of thi s character two metal s

having different coefficients of expansion,such as

steel and brass,are used instead Ofmetal and hard

rubber .

Thermostats Of th i s nature are much used in

incubators,and they can readi ly be combined w i th

electric apparatus to open or clo se ho t- ai‘

r valves ,


dampers , etc . , and thus regulate the supply Of

hot ai r , hot water , or gas .

A thermostat much used in fire alarm work has

a thin metal chamber which is air tight . An in

crease Of temperature causes the ai r to expand,

which swell s out the wall s Of the chamber and

closes an electric ci rcuit .

FI G. 40

The mercurial thermostat shown in Fig. 39 has

a glass tube Tand bulb containing mercury . Into

each end i s sealed a p latinum wire P P . U pon

the temperature ri sing to a predeterm ined degree ,the expanded mercury completes the c ircuit be

tween P P and the battery C and bel l B are put

in operat ion .

Fig. 40 i s the Ope n c ircu it system most used by

ALARMS 4 3

the fire alarm companies,only one c ircuit Of six

thermostats being i llustrated .

It wi l l be seen that i f any thermostat closes th e

circuit between the outer and inner W ires Of the

ring A B,current wi l l flow through the corre

sponding drop of the annunciator and w i l l attract

the armature A Of the re lay . This wi l l cause the

bel l to ring . AS the relay i s c onnected to the an

nunciator as before Shown for the annunciator bell ,i t Offers a common path for any drop to the bat

tery. Thus the bel l wi ll ring for any circuit , but

the indiv i dual drop only w i l l fall . In a Simpler

circuit the relay may be di spensed with and a

v ibrat ing bel l only used .

Thermostats may be operated on open or closed

ci rcuits,that i s

,they may give the alarm by clos

ing a circuit and ringing a bel l,or by opening one

and releasing a contact spring as in the burglar

alarm systeni to be described later .

Water L eve l Alarms; Where it i s des ired toSignal the ri sing or fal l ing Of water in a tank

above or below a given point,a water level in

dicator as in Fig. 4 1 may be used .

A hol low bal l H i s mounted on the end Of a

rod which sl ides vertical ly in guides,not Shown .

Adjustable stops S 5 press against a Spring

arm R,pressing it up or down , according as the


water level i s rising Or fal l ing . I f ri sing ,Rmakes

contact with the adj ustable screw A,i f fal l ing ,

with D,in both cases completing the electrical Cir

cuit'

Of the battery C and bel l B.

FI G. 41

Another and Simpler form i s shown in Fig. 4 2 ,

where the bal l H i s mounted on the end Of a

lever L p ivoted at P,its ri se or fall compl eting

the ci rcuit of B and C as before .


In both forms Of indicator , a means must be

prov ided that an undue ri se may not bend the

lever . Thi s may be accompl i shed by using contact

Springs instead Of contact screws ;i t i s , however ,then harder to adjust the indicator to fine differ

ences Of level .

In al l cases the contacts must be faced with

p latinum to prevent corrosion .

Burglar Alarms. A burglar alarm i s a dev i ce

for indicating the opening Of a door or window ,

by the ring ing of a bell or operation Ofan annunci

ator . The contact apparatus at the points to be

protected may either open an electrical ci rcu it or

close one, in the latter case being mere modifica

tions Of push buttons . The Simp lest form i s the

latter or open - ci rcuit method .

The Spring contact to be inserted in the door

j amb or window frame is SO constructed that

whi le under pressure the contacts are kept apart

and the circuit i s open . But when the door or

window i s opened,the pressure i s released and

a spr ing forces the contacts together .

Fig. 44 i s an open - ci rcu it window spring fitted

in the window frame SO that when the window

is closed the spring lug S is pressed inwards ,break ing

“

Contact with the base B.

I f the window i s rai sed,the lug fl ies to th e

ALARMS 47

position Shown by the dotted l ines,and mak ing

contact with B,completes the ci rcuit through bel l

and battery . These springs are fitted in the S ide

of the window frame in a vertical posit ion and

are enti rely concealed when the window i s shut .

In the closed - ci rcuit system the reverse hap

pens . Th e pressure Of the closed door or win

FI G. 45

dow keeps the contacts together and its open ing

enables them to spring apart;

In Fig. 4 5 i s a diagram Of a closed- ci rcuit

burglar alarm, C a cel l of grav ity battery

,R a


relay , F the fixed contact and M the movable con

tact Of the Spring, 5 a stud proj ecting th rough

the base Ofthe spring and pushed in by the closeddoor .

When the door i s closed, 5 being pushed in

,

FI G. 46

the circu it Of C,R

,F and M i s closed . Th e

magnets Of the relay hold the armature arm A

forward against a hard rubber contact . But when

S i s released,the relay circuit i s opened

,R loses

i ts power and A fl i es back,making contact . and

throwing in circu it bell B and battery L .

ALARMS 4 9

A form Ofbel l and relay comb ined is shown in

Fig. 4 6 . H ere the armature A i s held against the

magnets whi le the ci rcuit through the spring F

and batteryG is closed . But on Opening thi s c ir

cuit the armature fl ies back and makes contact

with an adjustable contact screw 5 putting in

ci rcuit a local battery C. The bel l is now practi

FI G. 47

cal ly a v ibrating bel l ;On a closed circuit it rings

unti l the circuit i s again closed or the battery runs

down .

A different connection Of the same scheme i s

Fig. 4 7, where only one battery i s used . Thi s

must be a grav i ty battery or some other closed

circuit battery . The ci rcuit can be easi ly traced

in the figure and needs no special description .


Both Of the latter schemes are inferior to one

using a separate relay . I f the circuit at the spring

were quickly closed again the bel l would either

stop ringing,or be SO hampered as to ring very

weakly .

FI G. 48

A relay made as in Fig. 48 has no spring sup

port to the armature A,wh ich fal ls down by grav

ity . The adjustable contact C i s screwed far back,

SO that the armature must fal l a cons iderable di s

tance away from the electromagnets before it

makes contact . This ensures that the armature

wi l l not be attracted and the bel l stopped from

r inging by a t e - closing Of the c1rcu1t at the door

or w indow spr ing.

A Shade spring (Fig. is made for either

ALARMS 51

open or closed ci rcuits . In operation,the Shade i s

pul led down and its string or ring hooked on

to H . This draws H up a trifle against a spi ral

spring and its lower end makes contact with an

insulated Spring 5 closing the circuit . I f the

Shade is disturbed , the sp iral spring on the lower

part Of H i s released . and it causes a break Of

contact with S in the directionof the arrow .

When made for open ci rcuit , 5 i s bent so that

FI G . 49

while under tension no contact is made,but re

l ease Of tension causes the contact .

Fig. 50 gives the wiring Of two windows and

a door on the closed - circuit system . It wi l l be

seen that the contact springs are al l in series,

opening a window or the door wi l l thus break

the circuit .

When setting the alarm at n ight by connecting

up the batteries,relay and bel l

,Should any one

Of these springs be open the relay armature wil l

not hold , and the bel l rings .


M isce l lane o us A larms. Th e Applegate elec

trical matt ing IS composed of wooden slats with

Springs so arranged that the weight Ofany person

stepping on it w i l l close a ci rcuit and ring a bel l .

It i s intended to be put under the ordinary door

mat or under stai r and room carpeting .

The Yale lock sw itch is a Yale lock and switch

combined . U pon any key but the right one being

inserted,a c ircuit i s closed and an alarm bel l i s

rung .

CH APTER V

Annunciators

Th e Annunciator. Th e mechani sm Ofan an

nunciator consists Of electromagn ets wh ich‘

allow

Shutters to drop or needles to move on the ci r

cuits being Closed . A bel l i s also rung in most

cases to cal l attention to the annunciator . The

number Of the circuit i s marked on the Shutter ,

or near the needle,either shutter or needle being

replaced by a reset dev ice, which may be mechan

ical or electrical .

Annunciator drops are made in a variety of

forms . Fig. 52 i l lustrates the principle under

lying nearly al l Of them .

When current flows through'

th e magnet coi l s

M,the armature A is attracted

,and being pivoted

at P,the lever hook H ri ses and al lows the


weighted shutter S to fal l and di splay a number

painted on its inside surface .

The needle drop in'

Fig. 53 i s one that has met

with great favor and works as follows "the soft

i ron core Of the magnet C has a hole dri l led

th rough it , in which turns the shaft 5 . An arrow

or needle i s attached at the front end over the

FI G. 53 FI G . 54

face of the annunciator . A notched arm B i s

fixed on the rear end Of the shaft and i s held in

a horizontal position by the end of armature A .

When the current flows around C,armature A

turns on its pivot towards the core of C,as in

Fig. 54, unlocking B,

which fal l s and thereby

partly rotates shaft 5 and the arrow .

When it i s desired to reset the arrow and arm,

AN N UN CIATORS 57

a button is pressed upwards,which ra ises a rod

carrying an arm R. This latter arm in turn

rai ses B to its former position,the heavy end

OfA fal l s , and its pointed end locks B.

Pendulum , or swing ing, S ignal s are used in ah

nunciator work , where there is a l iabi l i ty that the

FI G . 55

ordinary drop shutter would not be reset . They ,however

,only give a v i s ible s ignal for a few sec

ouds,and are therefore l iable to be overlooked .

In Fig. 55 a pivoted arm carrying a soft i ron

armature A and a thin plate B -having a number

on it i s free to sw ing in front Ofan electromagnetM .


When the Current flows in the electromagnet

the armature i s‘

attracted,and upon the circuit

being broken at the push , the armature i s rel eased

and the arm swings to and fro .

The drops Of an annunciator are wired up as

in Fig. 56 .

One end Of each coi l is attached to a common

FI G. 56

return w ire C,the other end goingto the push P .

When P i s depressed, t h e ci rcuit Of any drop is

through M along C through bell , battery and up

common battery w ire W back to other contactOfpush P . Depressing any push does not there

fore affect any other drop but th e one control led’

byi t .

AN N UN CIATORS 59

W iring up an Annunciato r . A diagram ofthe connections for an annunciator w i th a separate

bel l i s given in Fig. 57 . Where the bel l i s contained in the case a terminal wi l l be generallyfound for connection .

Th e figure Shows a wire running from the battery to one side Of each push button . Thi s i s the

common return , or battery wire, and saves instal

FI G. 57

l ing two wires from each push; I t Should be

larger, however, than the rest of the wires , gener

al ly about N O . 1 6 B. S .

All the w i res for an annunciator Should be run

before connecting up . There are different methods

Of sorting out the w i res at the annunc iator . One

way i s to connect the wires ( except Of course

common or battery return wires ) to the drops in

any order . Then an assi stant travel s from push

to push and presses each button,noting the


room numbers and the order in which they were

v i s ited .

AS each drop fal l s,its number and order i s

noted .

Comparing thi s with the l i st made by the assi s

tant wi l l Show the correct changes to make .

FI G. 58

For instance,Suppose pushes 1 , 2 , 3 , 4 5 and 6

were pressed in that order,and drops 3 , 4 , 5 , 1 ,

2 and 6 fel l in that o rder . Then the wires at

the annunciator would be changed as fol lows

6 would al ready be in its right place .

Another way is to commence by c twisting to


FI G. 59

AN N UN CIATORS 63

each room the top contact and push spring

ct are normally together .

one Of the pushes below the annunciator is

ed,battery F is thrown in series with the

the room .

t when the room push i s pressed its bel l i s

ut and the circuit; becomes l ike an ordinary

ciator c ircu it .

CH APTER V I

Annunciators and Alarms

Thre e W ire Re turn Call System . A threew i re return cal‘l annunciator sy stem 18 Shown inFig. 60 .

There are two battery w i res instal led , fromwhich taps are taken Off and led to each roomor push button .

Three way or return cal l push buttons areused as Shown at poin ts marked B.

In th e diagram , the bel l s are marked A ,the

drops in the annunciator D,the annunciator bel l

C and the return cal l buttons in the annunciatorE . Th e batter ies are as shown at F. Th e heavyblack outline encloses the annunciator mechan i smand connections which are drawn diagrammatical lyfor the sake Of clearness .

Three stations only are Shown on the Sketch ,

but the annunciators which are manufactured byEdwards and CO .

,I nc .

, Of N ew York ,are made

in al l standard Sizes .

I nstal ling E levator Annunciators. Th e in stal ling Of e lectr ic bel ls and annunciato rs in elevatorsdoes no t present any special problems , althoughthe apparatus usedmust be selected w ith a v iew to

64

66 ANN UN CIATORS AND ALARMS

its being suitable to withstand the shocks incidentto elevato r se rvice .

I n general th e w i res leading from the push buttons on the different floors to the bel l o r an

nunciator in the elevator , are flexible and made upinto a cable . One end of this cable i s attached tothe underside Of the elevat o r car

,the other end

being fixed usual ly to the elevato r wall,at a po int

m idway between the top and bottom Of the shaft .I n Fig. 61 i s Shown a diagram Of the general

ci rcuit used,detail s Of course differing in each

installation .

One po int to b e taken care Of in elevato r workis the attachment o f the cab les . Th e continualmovement tends to break the w i res at th e two endsi f good flexible cable is not used and the instal lation done in a workmanl ike manner .Elevator cable is a standard article and may be

procured through any electrical supply sto re .

That most commonly used consists Of th e requisitenumber Of copper conductors each composed of

16 strands'

N O . 30 B. and S . gauge soft and nu

tinned copper w ire . These flexible conducto rs areinsulated w ith two reverse wrappings Of cotton and

o ne braid of cotton . Th e insulated conductorsare cabled together with a steel suppo rting strandwhere extra tensile strength is requi red, as in th e

case of extra long cables . Th e number of con

ductors general ly ranges f rom 3 to 20 inclusive .

Th e w i res leading f rom the push buttons to thecable should be preferably rubber covered and

68 AN NUNCIATORS AN D ALARMS

braided . Only where economy at the outset is desi red may ordinary annunciato r or Offi ce w i res beemployed .

A connection b lock carrying binding posts is

used at each point where the cable connect s to th epush button w i res or to the annunciator . This may

be home-made o r purchased ready made,as desi red .

BurglarAlarm Annunciato rs. Al though almostany annunciato r may be used for Open circuitburglar alarm work

,they usually do not contain

certain devices wh ich are desirable in burglar alarmwork .

I n Fig. 62 is Shown a diagram Ofa burglar alarmannunciator, the view b eing schematic Of the backboard .

Th e references are as follows " A i s the mainalarm bell situated Wherever desired and connectedto the binding posts BB. Th e battery connectionleading di rectly to th e battery K i s marked C

and that leading to the contact spring i s markedD . Th e cut- Off sw itch E cuts Off the battery whileF is the constant ring switch . G i s the upper barand H the lower bar, while the letters J"denotethe indicating drops . Th e door and window springsare lettered 5 . At L i s a switch which may beused to disconnect the entire burglar alarm system . Where it is desi red to disconnect only a section at a time , the switch corresponding to thesection i s turned Off the upper bar G and on to thelower bar H .

70 AN NUN CIATORS AN D ALARMS

Clo ck A larm Ci rcuit . A diagram Ofthe W i ringand connections on th e back board Of al l clockalarms is i llustrated in Fig. 63 . This diagramembodies the principles Of the last desc ribed c i rcuit

,

but includes the ci rcuit of a clock ~operated alarm .

Be l ls for H igh V o l tages. Th e use Of electr i cbells on l ighting circuits is becom ing quite general ,as it obviates the necessity Of using batteries

,and

thereby Simpl ifies both installation and maintenance .

There is no fundamental Objection to operatingmake and b reak bells on electric l ight circuits . Pro

viding the vo ltage and amperage are the same ,there is l ittle difference between the current froma direct- current dynamo and that from a battery .

But owing to the higher voltages of the l ighting circuit over that generally employed f rom batteriesth e bel l co il s must be wound to high resistances tokeep down the current strength . There are alsoother slight changes to assist in suppressing sparking, as have been al ready treated on .

Where the ci rcuit is no t over 220 volts,the bel ls

are wound w ith fine w i re and have also sel f- contained resistance coils . For 500 volts and over , a

resistance lamp is connected in with the bell whichin this case is wound for a l SO- vo lt ci rcuit .These bells up to 6- inch and inc lusive w i ll operate

on ci rcuits of either dire ct or alternating current .Above this Size it is necessary to use specially

constructed bells on alternating current circuits .

M o st large hotels and Office buildings hav ing

72 _ _AN NUN CIATORS AN D ALARMS

di rect current l ighting service are using it for ringing bells and sim i lar wo rk to the total exclusionof batteries .

Where the number Of un its to be operated justifies it

,motor generato rs are operated in connection

with the lighting mains to produce a low vo ltagemost suitable for th e bells . Th e connections inth is case are no different to those when batteriesare employed .

Be l l -ring ing Transfo rmers. Th e best systemfor operating bells and annunciato rs from alte rnating current circuits is undoubtedly that employingsmall specially constructed transformers to reducethe voltage . These transformers are being useduniversally for hotel and Offic e wo rk where alternating current is available . They are Simple

,being

merely one or more coils of well insulated Wi rewound on soft i ron cores and h aving connectionsfor bo th the l ighting circuit and the bell ci rcuit .

As a general rule the co il s are divided as to theirnumber of turns or according to the ratio Of transformation desi red . For example

,I f the c ircuit

were 110 vo lts and 10 Volts was requi red for thebell ci rcuit

,th e total number Of turns in the trans

former would be connected , to the l ighting cir

cu it and to the bel l circuit .Th e bel l- ringing transfo rmers on the market are

made in several styles . One small style, Fig. 64,

fo r single residences, is for use on 110 volts and

produces a bell voltage or secondary vo ltage as it

AN N UN CI ATORS AN D ALARMS

FIG . 64

FIG. 65

BELL-RINGING TRANSFORMERS .

73


i s termed , of 6 vo lts . Another size,Fig. 65

,of this

transfo rmer h as three secondary voltages 6,12 and

18, each Ofwhich can be used by connecting to the

right binding posts .

I t i s to be noted that where the l ighting servicevo ltage or p rimary voltage varies from the above ,the secondary voltage del ivered to the bell circuitw i l l vary in l ike propo rtion . I t should also be notedthat a careless reversing Of the connections

,that

is connecting the secondary leads to the l ighting ci rcuits

,instead Of the primary leads would

cause a like high vo ltage at the other terminals ofthe transformer, raising it in due proportion in

stead Of lowering i t . Thus such carelessness wouldproduce a voltage of volts instead Of 6 i f atransformer intended to del iver 6 volts from a 120volt ci rcuit was wrongly connected .

Th e results m ight very wel l then be dangerous .

All t ransformers are proper ly marked , however,and such an error only occurs through ignorance orcarelessness .

Th e installation Ofthese bel l - ringing transformersis simplicity itself;they

‘

require’

nO care after installation and h ave met With the approval Of theNational Board

“

OfFire Underwriters .

Comb ination Circuits. Ci rcui ts intended primarily for electric b ell s or annunciato rs in housesand apartments may O ften be also made to servefor other electrical devices such as door openers ,house telephones

,etc . This subsidiary apparatus

76 AN N UN CIATORS AN D ALARMS

may be installed w ith a l ittle additional w iring orperhaps w il l no t need any other w ires, as whenbo th the devices are no t used at once .

Electrical door openers are great conveniencesand are p ractical ly indispensable where th e outsidedoo r i s on ano ther level to the location Of thedwel ler o r where two or more fam i l ies occupy thesame house . Th e device is simple

, consisting Of anelectr ically released spring- plate against which thelock bolt is no rmally h eld and a doo r opening spring .

When the door opener button is pressed, thesp ring plate is released

,releasing "the lOck bo lt bv

the same action . Th e door spring then forces thedoo r open enough to c lear the opener plate

,which

fl ies back into position when the button is released .

T'hese door Openers are made in several fo rmsfor door frames , such as those on thin doo rs , irongates

,for surface or rim locks

,for thick doo rs,

sliding doo rs and any other regular type “0 1 doo r .

'

Th e push button is the same as used for electricbells and may be located wherever desi red . Th e

pushes are w ired in multiple as shown in Figs . 66

and 67,which are two circuits Of a type -Of the

Western Electr ic interphone,a system Of house

telephones suppl ied for houses and buildings ofevery Size . Fig. 66 shows a ci rcuit which providestelephone service between the vestibule and

,the

apartments , th e door opener wi ring being c learlyindicated . I n Fig. 67 the c ircuit provides a moreextensive service

,enabling th e jan ito r, the apart

ments and the tradesmen to inte rco -mmunicate in


the most desi rable system . Th e doo r opener Wiringis also clearly Shown .

Th e conven ience Of having telephone connectionin the house o r hotel and its advantage s over speaking tubes are t oo well known to need extendedcomment . Where electric b ells have al ready beeninstalled it is quite feasible now to use the samewi res for telephones also .

Telephone sets especial ly designed for this service are manufactured by the Western E lectric Company “in thei r interphone series . They are simpleand compact

,and may be installed by anyone wh o

can put up an electric bell .

Fi re A larm C ircuits . A fire alarm ci rcui t suitable fo r factories

,pr ivate plants or groups Of

buildings is shown in Fig. 68 . It is a series system ,

w ith Clo sed ci rcuit,the gongs sounding whenever

the ci rcuit is opened whethe r by th e contact breakerin the boxes or by th e accidental breaking Ofa w i re .

This insures that it remains in good wo rking order ,as when any part o f the c i rcuit is opened , a warning tap i s sounded on every bell or gong .

Th e boxes have contact breakers which send a

separate number of impulses for each box , thus announcing the box number on each gong . Th e boxesand gongs may be located anywh ere, as the systemis perfectlvflexible .

Th e reference letters in the diagram are as follows " C indicates the gongs which are p referablyof the electro-mechan ical type

,a co iled sp ring pro

80 AN NUN CIATORS AN D ALARMS

viding fo rce for the blow,electricity b eingmerely

used to release and retain the hammer or strike r .

Th e alarm bo xes are marked BB and the batterywhich is of th e closed circuit type is marked D .

I nterior Fire A larm Syst em . Another syst emsu itable more particularly for indoo r operation isi llustrated in Fig. 69 . H e re the alarm is given bybreaking the glass f ront Of an alarm box and re

leasing o r pressing an electr ical contact .Th e box sounded indicates by causing a drop to

fal l on an annunciator and at the same time ringsan alarm bell . Th e latter are generally p rovidedw ith constant ring attachments

,which keep the

bel l sounding until Sh ut Off.

Th e annunciator Shown in the diagram hassw itches for co ntro ll ing each individual bell c ircuit,and also fo r contro l Of the entire system .

There is no p ractical l imit to the number Of sta

tions in this system,it being determ ined by the Size

of the annunciator used or by other obvious facto rs .

Th e reference letters on th e diagram are as follows " A,

alarm b e l ls which may be located whe reever desired . B

,break - glass alarm bo xes also lo

cated at convenient po ints . C,annunciator drops ,

D,sw itches on annunciato r which cont rol each in

div idual bell c i rcuit, enabl ing any circuit to be cutout

,cut in or tested Without disturbing any o ther

circuit . E i s a general alarm sw itch,causing all

bel ls to ring at once when it is operated .

Th e battery F varies w ith the number Ofbells and

FI RE AL ARM SYSTEMS 8 1

boxes and the length of l ine , from three cells upwards . A cut—out switch H is added to cut out

the ent i re system by open ing the battery wi re .

FI G . 69

Th e annunciator bell is at I,an auxiliary bell being

added in multiple w ith it when necessary .

FI RE ALARM SYSTEMS

Fire Alarm System for Conside rable Areas.

Where the area is mo re extensive and the numberof stations considerab le

,th e system illustrated in

Fig. 70 is very suitable . I t consists of the requisitenumber of break-glass boxes

,bells and a more

elabo rate annunciato r system . I n general detai ls itresembles the last system , but uses a relay to sendout th e current for ringing the alarm bells .

When a box operates, the current impul ses senton the l ine act on the relay instead of directly onthe bells . Each stroke of the relay closes a localc ircuit which includes the bells and th e battery .

This system does away .w ith large batteries andis very en

'

conomical o f w i re Th e current neededfor the relay is very small

,whereas in a direct sys

tem of any size , the current and voltage to ring anumbe r of bel ls located at wide intervals would beprohibitive .

Th e reference letters are as fol lows " AA arethe alarm bells

,BB the break - glass alarm boxes

,

C is th e annunciato r be'l l,D is the relay which re

mains clo sed when an alarm comes in keeping th e

bells constantly ringing until shut off. E i s a re

sistance co il and F is the battery .

A system cutout sw itch G and I f sw itches on

the annunciator for controll ing individual ci rcuitsare also provided . H H are the annunciato r dropsand K is a constant- ring sw itch which can also beused for a general alarm to

“

r ing al l the bells atonce .

D ub e lle’

s Famous Formu las .

KNOWN As

N on Plus Ultra. Soda. Fountain Requisites of M odern Times.

By G . n . B URE L L E .

A practicalRecezlfitBoo/efa; fi ruggi sts, Ckemists, Confectioners and V endemof Soda Water.

S l N OPS lS O F CON TEN TS .

INTRODUCTION —N ote s on natural fru it ju ices and improved m e

th ods for th e ir p re paration . Se le cting th e fru it . Wash ing and

pre ssing th e fru i t . Tre ating th e ju ice . N atural fru it syrups andmode ofpreparation . S imp le or stock syrups .

FORMULAS .

FRU I T SYRUPS .

—Black be rry,black curre nt , b lack raspbe rry, ca

taWb a ,ch e rry, concord grape , cranbe rry

,l ime

, p e ach , p ine app le ,

p lum . qu ince , raspbe rry, red curre n t , red orange , scuppe rnong grape .

strawbe rry . Wi ld grape . N EW I MPROV ED ARTI PI CI AL FRU I T SYRUPSApp le , apricot , banana,

b itte r orange,b lack be rry, b lack curren t ,

ch e rry , ci tron , curacoa , grape , grose i l le ,lemon ,

l ime mandarin . mu l.

be rry,ne ctarine

, peach , pear , p ine app le , p lum , q u ince ,raspbe rry ,

red current , strawbe rry,swe e t orange ,

large rine ,van i l la . FANCY

SODA FOUN TAI N SYRUPs.-Ambrosia , cap i llaire , coca-Rina

, cocavani l la , cocawmo

,exce lsior, impe rial , k ola coca,

k ola-k ina , k ola-vani l la .

k ola-vmo , ne ctar , noye an ,orge at , Sh e rb e ‘

,syrup of rose s . syrup of

v iole ts. ART IFICIAL FRU IT E SSENCES .—App le , apricot , banana , be rg

amot . black berry,black' ch e rry,

b lack currant , blue be rry , c i tron ,

cranbe rry, goose berry, grape . lemon ,l ime fru it, m e lon

,n e ctarine

,

orange , pe ach , pe ar , p ineapp le , p lum , q u ince ,raspbe rry , red curran t ,

strawberry . CONCENTRATED FRU IT PHO SPHATES . ACld solution of

plh osph ate , strawbe rry, tange rine , w i ldch erry— 2 9 different formu las.

EW MALT PHO SPHATES—36 . FOREIGN AN D DOM EST IC WINE PH o sPH ATES -

9 . CREAM -FRU IT L ACTARTS —2 8 . SOL UBLE FL AV ORING Ex

TRACTS AND E SSENCES— I 4 . N EW M ODERN PUNCHES —I 8 .'M ILK

PUN CH Es- I 7. FRU ITPUNCHES—32 . FRU I T M EADS - 1 8 . N EW FRU .T

CHAM PAGNES—I 7 . N EW EGG PHO SPHATES— l 4 . FRU IT JU ICE SHARES- 24 EGG PHO SPHATE SH ARES . H OT Ec o PHO SPHATE SHARES .WINE BI TTER SHARES—1 2 . So L UBLE WINE BITTERS EXTRALTS— I Z

N EW ITAL IAN L EMONADES—I 8 .’

I CE CREAM SODAS—3g N ON .PO I SO NOUS COLORS . FOAM PREPARAT IONS . M I SCELLAN EU I

'

S FORM ULAS —2 0 .

L ATEST N OV ELTIES I N SODA FOUNTAIN M IXTURES—7 . TONICS .—Be e f,

iron and c inch ona;h ypop h osph i te ;be ef and coca ;be ef, W ine and

iron be ef, w ine ,iron and cinch ona coca and calisaya . L ACTARTS .

- I xnpe rial tea ;moch a coffe e ;ne ctar;Pe rsian sh erbe rt . PUNCHES .ExTRACTs.

-Columb ia root be e r ; g inge r ton ic ; soluble h op ale

L EMONADEs.—Fre nch ;V ienna . Eggnogg . H op ale . H o t tom . M alt

wine . Sh e rry cobble r . Saratoga m i lk sh ak e . Pancre tin andW ine .

Kola~coco cordial . ’ I ron malt ph osph ate . Pe psin ,w ine and iron , e tc

157 Pages, N early 500 Formulas. 12mo . Cloth .

ANEWAMERICANBOOKON I NDUSTRIAL ALCOHOL.

A PRACTI CAL H ANDBOOK ON TH E

ist illat ion of I coh o l

FROM FARM PRODUCTS AND

DE" NATURI NG ALCOH OL .

Inc ludingth e Free Alcoh o l Law and itsAmendment , th e Governm en t re gu lat ion s t h e refore and a numbe r of U . S . gove rnm ent

aut h oriz ed de -maturingformu las.

I n t h e pre parat ion of t h is, t h e second edit ion , t h e auth or h asfo l lowed h is origina l p lan ofwrit inga p lain p ract ica l h andbook on

t h e manufact ure of a lcoh ol and de -naturing for industria l purpose s . Th is industry is bound to grow to enorm ous proport ionsas it h as in Ge rmany wh e re ove r ga l lon s w ere manu

factured last year princ ipa l ly in sma l l farm dist i l le rie s . Th is workis n o t in tended as a sc ient ific treat ise but as a h e lp to farme rsand oth e rs w ish ing to go int o th is industry on a mode rate sca le .

Th e origina l mat te r h as be en care fu l ly re v ised. Some of th ech apt e rs rewrit ten and a ve ry con side rab le amount ofn ew informa

t ion added. 2 Th e t ota l num b e r of illustrat ions‘

b ro ugh t up t o 60

inc luding a number of p late s giv ing t h e layout‘

of dist i l le rie s.

Contents ofCh apters.

1 , Alcoh ol , ‘

l tS various forms and source s . 2, Th e preparat ion

of mash e s and Fe rm en tat ion . 3 , Simp le D ist i l l ing Apparatus. 4,

Mode rn D ist i l ling Apparatus . 5 , Re ct ificat ion , 6 , Ma lt ing. 7Alcoh ol from Potatoe s . 8 ,

Alcoh ol from Grain , Corn ,Wh eat , Rice

and ot h e r Ce rea ls . 9 ,Alcoh ol from Be e t s . 10 ,

Alcoh ol from Molasse sand Sugar Cane . 1 1 , Alcoh olom etry . 12 ,

D ist i l l ing Plan t s . Th e irgen e ra l arrangemen t and e qu ipm en t . 13 , D e -natured Alcoh ol andU . S . Aut h ori z ed De -

‘

nat I iring Definaturing Regulat ions in t h e Un ited State s. Index .

281 pages, 60 illustrations and p lates, 12mo . , cloth ,

l IBRARY USERETURN TO DESK FROM WH I CH BORROWED

LOAN DEPT.

THI S BOOK I S DUE BEFORE CLO

MAY 2011979

L ID 62A—30m(J65 34 8 1 019 4 1 2A— A-32

Electric Bells and Alarms

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Transcript of Electric Bells and Alarms