A Powerful Stun GunUpdated "Feb 16 2005"Latest Update "Nov, 8 2009"

The version is Quite Powerful, IF T1 and T2 are made Correctly.  

"I DO NOT RECOMMEND ANYONE BUILD THIS DEVICE".  

This Is Presented HERE, Only for the Purpose of Demonstrating:"How Simple a Deadly Device can be Constructed".  

And If you do NOT Understand the Construction Details Give Below, Youare DEFINATELY Not Understanding enough to Even Attempt Making it.  

I WILL NOT Offer any Further Construction Details.NOR WILL I ACCEPT RESPONSIBILITY FOR THE STUPIDITYOR INJURIES, RESULTING FROM PERSONS ATTEMPTINGTO BUILD OR USE THIS DEVICE.

BUT IF YOU DO SO, IT IS TOTALLY AT YOUR OWN RISK.  

"T1"   Was Home Built using a "Magnetics" Ferrite Core # "42620" and a Bobbin # "PCB2620-12".

The Primary Consists of a Dual 18 Turn Bifular wound coil using #26 AWG Wire.It requires 2 layers, with "Nomex" Insulation between them, As well as a layer of Nomex over the Primary.

The Secondary Consists of 8 Layers of 40 AWG Double Insulated Enamel wire with aproximately 40 turns per layer,Centered on each layer so there is a dead space on either side. This Prevents possible arcing.

Additionally a .003 Inch thick "Nomax Paper Insulation" is Placed between each layers. Before Assembly, the Ferrite core is Gapped to 5/1000 of an inch.

"Nomex:"   Is one of many Special Insulator types of paper used in the Transformer Winding Industry.Alternately you can use other Insulators such as "Fish Paper", Although they are Not as Good.

With this Transformer Connected In the Circuit as Shown, Current draw is about 250 Ma at 12 volts With NO LOAD.

With the Diodes, Caps, SCR and T2 connected in a Compete Circuit,   "The Current draw can Exceed 2 Amps".

EVEN MORE POWER:   A Bigger T1 Can be made Using a 42625 Core and a PCB2625 Bobbin.The Primary Consists of 14 Turns Bifular Wound on Two Layers.Change the Secondary Wire to a 38 AWG, Double Insulated Wire and use about 45 turns per layer.Fill the Bobbin with as Many layers as Possible, leaving a bit of Clearance between the last layer and the ferrite core.The Gap Remains the Same at 5/1000 of an inch.This Results in a Faster Charging Time and a Higher Supply Voltage.

"T2"   Was Wound on a "Fair_Rite" Rod, # "4077375211". It Measures .375 OD by 2 inchs long."ANOTHER T2"   Was Wound on a "Fair_Rite" Rod, # "4077312911". It Measures .315 OD by 1 1/2 inchs long.Both these are Material 77 and it worked EQUALLY WELL.But If you think All Ferrite Rods are the same and you can Just use Any Ferrite Rod,THINK AGAIN, "YOU ARE BADLY MISTAKEN".  

I Stock Both these Rods, But I Only have a few of the first one above.And Lots of the second one.

First Apply a layer of .003 Nomex Paper Insuation. Now wind a Primary of 25 Turns, 22 AWG wire in a single Layer.It is than covered with a .005 or .008 Nomex Paper insulation.The .008 Nomex is a bit better to keep this Layer more even to wind over.

The Secondary is wound over this with 40 AWG, Double Insulated Enamel Wire and aproximately 180 turns in the first layerand than LAYER Wound in declining layers at about 10 turns per layer. A layer of .003 or .005 Nomex is placed between Each Layer1) 4002) 3903) 3704) 3605) 3506) 3407) 3308) 3209) 31010) Final Layer about 125 Turns with the Output taken off Directly in the Middle,

Lenghtwise.And a Final Couple of layers of Nomex are placed over top and Taped in place.Total Turns, About 3,675 turns. But the Exact number of turns is Not All that Critical.The Absolute Ideal is to "Pi" Wind the Secondary, But this Results in a Different number of turns and only a few layers.

This Completed Transformer is than Submersed in Epoxy, (Ideally in a Plastic Form to contain it around the transformer.)and than placed in a "VACUUM CHAMBER" and Subjected to a high Vacuum of at least 25 inches of Hg.for at least 10 Minute. I usually Repeat this Vacuum Process Two or 3 Times.

The Reason for this is to Remove all Air Bubbles and have the Epoxy Totally Penitrate between the Windings.The Epoxy Surrounding the transformer sould be at leat 1/4 inch thick over the Outer layer and 3/8 inch over the Ends.

Spark Gap DistanceThe Correct Spark Gap Distance is Essential in the Completed Unit.The Maximum Distance is a Function of How Well You Made T2.Too Great of a Spark Gap Distance and T2 Shorts Out, Internally or Externally

NOTE: Some Info May have been Omitted in the Above!This was My Prototype and I am Not Responsible for any Errors or Omissions.

A Real Misconception about Stun-Guns, Is the Voltages.It Sound Good in the Advertisements, But it is Current that does the damage.The Pulsing Effect of the Stun Gun adds Enormously to the Effect, But any spark capable ofpentrating through the clothing and Surface Skin is totally sufficant to do the job of Penitration.

A blue spark looks pretty, but a yellow spark is"Much Higher Current" and REALLY MORE DANGEROUS.

MORE People are Killed by Relatively LOW Household Voltagethan any other electrical supply.

Points to Ponder,   REMEMBER: In Reality, the spark gap determines the "Actual Voltage Available at the probes".With a spark gap of 1 to 2 inches or so, it may be No-where near the 100,000 VoltsAnd DIFINATELY NEVER the 750,000 volts that these manufacturers make claims of.

IF YOU REMOVE THE SPARK GAP, it MAY Attempt to Attain these VoltagesBut in the Process it will short out across the surface of T2.

"High-Voltage Zappers""It doesn't take much to generate enough high-voltage to curl your hair."

 by Charles D. Rakes

 Rewritten by Tony van Roon (VA3AVR)

The two circuits listed here are for the experimenter having a touch of Ben and Nikola's fascination for working with high-voltage. But unlike those two brave pioneers who flirted with lightning and gigantic spark coils, our high-voltage circuits are mild in comparison, having outputs of less than 50 kilovolts (KV). Even so, don't ever become careless when working with high voltage. To do so could be dangerous to your health and your good nature. So please take care.A circuit that generates a high voltage by discharging the energy stored in a large-value capacitor through the primary winding of a high-turns-ratio step-up transformer is known a a Capacitor-Discharge (CD) system. It's the same concept used by many of the high-performance auto-ignition systems to produce a super-hot spark. It's also the same kind of system used by some of the top-of-the-line electric fence chargers. And let us not forget one of the most popular persona-defense devices now on the market, the electronic Stun-Gun, which also generates its zap with capacitor-discharge circuit.

How we make the ZapAs shown in the circuit of Fig. 1, step-down transformer T1 drops the incoming line voltage to approximately 48 VAC and, in the process, adds a degree of safety through the transformer's primary-to-secondary isolation from the power line. T1's 48-volt secondary is rectified by diode D1; the resulting DC chargers capacitor C1, through current-limiter R1, to a voltage level pre-set by R4. When the voltage on R4's wiper reaches about 8.6 volts, Q1 begins to turn on, drawing current through R7 and the base-emitter junction of Q2. Then Q2 turns on and supplies a positive voltage on the gate of silicon-controlled rectifier Q3. The positive gate voltage causes Q3 to conduct, thereby discharging C1 through the primary winding of step-up transformer T2; the end result is a high-voltage arc at the output terminal (X).The value of the high voltage developed at T2's output is determined by the value of C1, the voltage across C1, and the turns ratio of T2. The frequency or pulse rate of the high voltage is determined by the resistance of T1's primary and secondary windings, the value of R1, and the value of C1. The lower the value of each item, the higher the output pulse rate; the peak output voltage will remain unchanged only if C1's value remains unchanged.

Parts List, Fig. 1All resistors are 1/2-watt, 5%, unless otherwise noted R1 = 100 ohms, 5 watts, brown-black-brownR2,R5 = 3K3 (3.3K), orange-orange-red R3 = 10K, brown-black-orange R4 = 10K, potentiometer R6 = 33K, orange-orange-orange R7 = 15K, brown-green-orange R8 = 100K, brown-black-yellow R9 = 2K2 (2.2K), red-red-red

CapacitorsC1 = 220 or 440uF, 75-100 volts, electrolytic, or 10uF 220VAC motor capacitor (see text)

Semiconductors D1 = 1N4003, silicon rectifier

D2 = 1N756, 8 volt zener diode Q1 = 2N2222, NPN transistor Q2 = 2N3638, PNP transistorSCR1 = NTE5463, 10-amp, 200 volt, silicon-controlled rectifier (SCR)

Other ComponentsT1 = Step-down transformer, 48VAC, 300mAT2 = Auto ignition coil, or substitute (see text)Building the CD SystemThe circuit shown in Fig. 1 is non-critical, so any parts layout and mounting can be used; perfboard wiring board will probably make for the easiest assembly. But no matter what kind of construction is used, keep T2's output terminal (labeled X) at least 3 inches clear of all circuit components, yourself, and anything else that can conduct electricity.The transformer used for T2 can be almost any 6- or 12V auto-ignition coil, but one designed with a high turns ratio for a capacitor-discharge ignition system will produce the greatest output voltage. The CD coil that we used produced a spark 1-1/4 inches in length from the output terminal to the coil's common terminal.An old (but good) TV flyback transformer can also be used for T2. Simply wind about 10 turns of test-lead wire around the transformer's ferrite core and connect the free ends of the wires to the points labeled "A" and "B" in Fig. 1. Some experimenting with the number of turns may be necessary to obtains good results with that type of transformer. Our experiments with the TV flyback produced a voltage that would jump a 3/4 inch gap.If a small-engine repair business is located in your area, see if the owner or mechanic will give you a few of the old ignition coils. If you obtain several old coils, one of more should be unusable. To produce a high voltage with a small-engine ignition coil, connect the primary leads to terminals "A" and "B", and a 1/2 to 3/4 inch spark should be possible.To make a "magnetic charger", select one of the ignition coils that has a good primary winding and carefully remove the secondary winding from the coil's core. Connect the primary to terminals "A" and "B". Position any object that you want to magnetize on the exposed core laminations and apply power; you should hear a "Zap" sound as the magnetic pulses hit the metal object.

Maximum SparkIf you want to achieve a maximum spark, select a CD ignition coil, and use a 440uF, 75-100WVDC electrolytic capacitor for C1. Using a DC voltmeter, monitor the voltage across C1. Adjust R4 so that the Q3 fires when the charging voltage across C1 reaches between 50-55 volts. That setting should produce a spark 1-1/4 to 1-1/2 inches long every second or so.To obtains a faster pulse rate, with some reduction in the output, change C1 to a 10uF, 220VAC motor capacitor (or any other lower value with a rating of 75 volts or more). Experiment with different component values to obtain the desired results.An excellent electric fence charger can be made by building the CD circuit in a suitable case and selecting a 220uF capacitor for C1. Adjust R4 for one to two pulses per second.

Battery-powered High VoltageA high-voltage generator circuit that can operate from a battery or other low-voltage DC source is shown in Fig. 2. Output voltage great enough to jump a 1-inch gap can be obtained from a 12-volt power source, and with a higher pulse rate that the circuit in Fig. 2.

A 555 timer IC is connected as an astable multivibrator that produces a narrow negative pulse at pin 3. The pulse turns Q1 on for the duration of the time period. The collector of Q1 is direct-coupled to the base of power transistor Q2, turning it on during the same time period.The emitter of Q2 is direct-coupled through current-limiter R5 to the base of power-transistor Q3. When Q3 turns on, there is a minimum resistance between its collector and emitter. That causes a high-current pulse through the primary of T1, which generates a very high pulse voltage at T1's secondary output terminal (labeled (X). The pulse frequency is determined by the values of R1, R2, and C2. The values given in the Parts List were chosen to give the best possible performance when an auto ignition co8ild is used for T1. Here too, a CD-type ignition coil will produce the greatest output voltage.Performance wiring board construction is a good choice for this circuit, but remember to be careful when working near the output terminal of T1 while the power is on.

Parts List, Fig. 2All resistors are 1/2-watt, 5%, unless otherwise notedR1 = 10K, brown-black-orangeR2 = 4.7K, yellow-purple-redR3 = 1K, brown-black-redR4 = 100 ohms, brown-black-brownR5 = 15 ohms, 5 watts, wire-woundR6 = 270 ohms, red-purple-brown

CapacitorsC1,C3 = 0.22uF, 100 volts, Mylar C2 = 0.47uF, 100 volts, Mylar C4 = 470uF, 25 volts, electrolytic

SemiconductorsIC1 = 555 timer (not the CMOS type) Q1 = 2N3638, or NTE129, PNP transistor Q2 = 2N3055, or NTE130, NPN power transistor Q3 = 2N3055, or NTE130, NPN power transistor with heatsink

Other ComponentsT1 = Auto ignition coil (see text)

Copyright and credits:This article originally was written by Charles D. Rakes and the editors of "Electronics Now" and "Popular Electronics" magazines and published by Gernsback Publishing, 1992 (Gernsback Publishing is no longer in business).

Editor's note and Disclaimer: This device is presented here for educational and experimental purposes only as part of our High-Voltage Projects. Build and/or use at your own risk. The Sentex Corporation of Cambridge Ontario, host of "Tony's Website", or Tony van Roon himself, cannot be held liable or responsible or will accept any type of liability in any event, in case of injury or even death by building and/or using or misuse of this device or any other high-voltage device posted on this web site. By accessing, reading, and/or printing this article you agree to be solely responsible as stated in the above disclaimer.

A High-Voltage Pulse Generator"If you've ever wanted a high-voltage generator to create neat lightning effects, perform

Kirlian photography experiments or play with neon lights, then this one is for you!."

 by Dale Hileman, re-written by Tony van Roon

We will describe a laboratory pulse generator using an auto-ignition coil and capable of delivering a train of pulses up to 30,000 volts. With a couple of minor circuit and construction variations, the project is suitable for use as an electric-fence charger, operating at a lower voltage, but capable of much higher output current.

Applications for a high-voltage spike are numerous: electromagnetic and radio-frequency interference (RFI) studies, electrostatic-discharge simulation; investigation of insulation breakdown; flammability experiments; strobe effects; etc. A DC power supply or battery is required, and pulse potential may be varied simply by changing the supply voltage. With a 12.6-volt input, the ignition-coil model delivers its maximum pulse, but a unique multivibrator-driver circuit makes operation possible down to a supply voltage as low as 1.5 volts, yielding an output pulse of only a few hundred volts. Its pulse frequency is set by a front-panel control, with a range from about 0.3Hz to 20 Hz.An ignition coil, however, is not well adapted to the fence-charger application since its

output resistance is so high: typically 10,000 ohms. Thus its output pulse is strongly dependent on loading. With a short fence, long sparks might be struck at risk of igniting brush; while on the other hand, with a long fence, shunting by weeds or by dirt and moisture may reduce its output voltage below and effective value. Hence for the fence-charger version the rate prf control must be omitted fro reason of safety.No-load output of the fence-charger option is typically 4 Kv pk (kilovolts peak), or about half that valuer when connected to a 1-mile fence. A car battery powers the fence-charger model for about four months before recharging is needed (at recommended pulsing rate of 20 pulses/minute).Two lamps mounted on the circuit board and visible through the see-through front panel are important indicators of the unit's performance.

Precautions:While a single jolt from an ignition coil is itself rarely traumatic, the resulting-reflex muscle contraction could have unfortunate consequences. If a continuous train of pulses causes you to involuntarily grasp the high-voltage conductor, for instance, you might not be able to let go. On the other hand, if proper return circuit is not provided, an equally distressing shock could be had by contact with the primary circuit. Because the ignition coil is an autotransformer, the return circuit for the high-voltage pulse includes the power leads. Therefore, one side of the power supply should, if possible, be Earth grounded. That precaution besides shock by contact with the power leads, also precludes arcing within the power supply itself as the high-voltage pulse seeks the shortest return path.Applying that reasoning to the fence-charger option, we can see why a fixed pulse rate is specified, as there is a strong likelihood of accidental human contact with the fence wire; a rate of 60 pulses per minute or less being considered safe. Also, since there is a good chance of personal contract with the power leads, a good ground connection is essential, as with any electric-fence system. For maximum safety, we recommend a battery supply for the fence-charger system.If you should happen to reverse the power-supply lease to either project, the current-limitation lamp, a large automotive bulb easily seen in the photos, lights brightly to warn you . However, the equipments must not be allowed to remain in this condition for more than a few seconds. Even if you never expect to make this mistake, the lamp should be included because it limits excessive surge currents that could otherwise occur under some operating conditions and which could blow the power transistor.

About the Circuit:As shown in Fig. 1, free-running variable multivibrator Q1 and Q2 drive Darlington power amplifier Q3, which makes and breaks the primary current to coil T1 as in an auto ignition system. Duty, or "dwell" is a few milliseconds, and the high-voltage pulse is generated at the end of the period when the circuit is broken and the field of T1 rapidly collapses trough the winding.An unconventional multivibrator circuit was developed to provide high saturation currents over a wide range of supply voltages. In this design both transistors Q1 and Q2 conducting at the same time and both cut off at the same time. Another unique feature; for safety in the fence-charger application, the circuit is designed to automatically shut down if driver Q2 should fail to conduct for any reason (fluctuation of powersupply voltage, intermittent connection, etc.)

Starting with both transistors cut off; C3 is discharging, its negative plate rising toward ground at a rate determined by various series resistances; while its positive plate is held near zero volts by a relatively low-resistance path through R6 and R7 and a resistor internal to Q3 across its emitter base junction.Capacitor C3 discharges fully, and then begins charging in the opposite direction as its negative plate rises above zero volts.

When Q1 begins conducting, and its collector voltage has dropped far enough to start Q2 conducting also, then a positive-feedback action is initiated, forcing both transistors into saturation. At the same time, power transistor Q3 is turned on by the current supplied through R7.Dwell is determined by the time constant R6 x C3. When the charging current of C3 diminishes below the value which will sustain conduction of Q1, then a regenerative action is again established, this time cutting off all three transistors. It is that moment the high-voltage pulse is generated.

Further Details:Capacitors C5 and C6 form a voltage divider which ensures rapid cutoff of Q1; while C6

acts as a bypass to prevent Q1 from being retriggered by pickup of the high-voltage pulse.Dwell must be long enough to permit the filed around T1 to be fully developed to its steady-state condition under all anticipated conditions of loading. Although the period is not critical, it may be set for optimum results with a particular coil or transformer, as described later.A higher capacitor value at C3 is specified with the fixed-frequency, or fence-charger version, for reasons of safety. It allows the use of a lower resistance value for R2, reducing the shunting effect of dirt or moisture which might otherwise cause a significant increase in the repetition rate. That is the reason we specify an axial type for C3, so that its pads are more widely spaced than they would be with a radial.

Power Amplifier:Because the field of T1, as might be supposed, collapses through the primary as well as the secondary, the inductive "kick" comprises a positive pulse on the collector of Q3. Capacitor C4 is required, as in the conventional auto-ignition system, to prevent excessively rapid voltage build up. Nevertheless, that reactive voltage reaches several hundred volts, and we take advantage of it to light neon indicator NE1. Thus, each flash verifies the integrity of the power amplifier circuit.If no arc is drawn, the positive pulse on the collector of Q3 is followed by a negative-going excursion. Transistor Q3, designed for inductive loads, contains a shunt diode which prevents that

"backswing" from being applied to the base through the base-collector junction. That diode also protects Q3 if the power-supply leads are accidentally reversed.Automotive lamp I1, as we said, limits surge currents occurring as a result of various normal operating conditions, as well as accidents, such as the reversal of power-supply polarity. Also, it absorbs the energy of the backswing.

The Transformer:Practically any 12-volt ignition coil having a primary resistance of around 1.5 ohms will work as T1 for the high-voltage pulse generator, but there's a minor consideration in the choice of a transformer for the fence-charger project. A common 12-volt 1-amp transformer with 115-volt primary can be used here--hooked up backward of course, so that the 115-volt winding serves as secondary.The rapid collapse of its filed when Q3 cuts off, as compared to the relatively slow 60-Hz sinewave for which it is designed, explains how several thousand volts can be developed across the 115-volt winding (E=L di/dt). That winding will ty0pically be found to measure 30 to 120 ohms DC, while the 12-volt winding will have a resistance of around 1 ohm. The author has tried many such transformers for T1, including the Stancor P-8392 and P-8393. (The latter provides a somewhat bigger jolt although it costs more than the former.) The problem, however, lies in the breakdown rating of the 115-volt winding.In most transformers of the species, the winding is rated for breakdown at 1500-volts RMS (corresponding to 2100-volts pk), with a safety margin that may vary depending on the

manufacturer; the Stancor rating proving remarkably conservative. The author subjected the winding of a P-8393 to 40 million pulses of 4-Kilovolt amplitude without breakdown. However, he does not guarantee equally good luck in your application.One way to preclude breakdown with such a transformer is to always operate the fence charger with an appropriate load. If your fence isn't long enough to load T1 to 2-3 Kv pk, you could reduce the supply voltage: Say, use a 6-volt battery instead of 12-volt. Or you could substitute for build I1 a type having a lower current rating, and there for a higher resistance. Either of those approaches, naturally, will somewhat reduce the effectiveness of the unit.

Other Parts:A type MJE5742 transistor is specified for Q3, rated at 400-volts under heavy inductive load. However, you can at some risk substitute the cheaper MJE5741 (350-volt rating), depending on T1. In any case, breaking the circuit to an inductive load is tricky and so if you plan extensive experimentation you should obtains a few spare Q3's.Potentiometer R9 for the variable pulse generator project can be any 2.5 mega-ohm unit from the junk box. If you use one with a linear taper, though, you will find the control very touchy at the end of the frequency range. The simplest resolution of that minor inconvenience is to use an ordinary audio-taper potentiometer connected backward; that is with the high end of the frequency range at the CCW (Counter Clockwise) end.For reasons already mentioned, the time constant C3XR6 determines dwell, or "on" time. As we have said, dwell is not critical; but if the capacitor you use for C3 is a low quality part with an excessively high equivalent series resistance (ESR), the dwell may turn out to be greater than necessary to serve the needs of T1. If in doubt, use a tantalum type for C3.

The Incandescent Lamp:We have emphasized the importance of I1, the current-limiting lamp, and have specified a type 1156 automotive bulb. The merit of an incandescent bulb as a protective device lies in the dependence of its resistance upon the value and duration of applied current. With a cold resistance of only about 1/2-ohm, the type 1156 degrades performance only slightly; but in the case of a current surge or accidental short circuit, its resistance quickly rises to a "hot" value or around 6 ohms, sparing power amplifier Q3 from the devastating requirement of breaking an excessive current into an inductive load. Nevertheless, there is some leeway in the selection of I1.For instance, in the lab-generator version where the load has a DC resistance of 1.5 ohms, a lower-resistance bulb will give a slightly better spark at high frequencies. The author has used a type 1157 bulb here, connecting its two filaments in parallel, with satisfactory results. On the other hand, as we have indicated above, to prolong the life of T1 in the fence charger, you may elect a lower-current or higher-resistance bulb. Try the smaller of the two 1157 filaments, alone before experimenting further. After the unit is built feel free to try others.

Parts List for the Fence Charger:

SemiconductorsD1 = No D1 in project; please ignoreD2 = 1N914 silicon diode or similarQ1 = 2N3904 NPN si transistor or similar

Q2 = 2N3906 PNP si transistor or similarQ3 = MJE5742, 8A, 400V, NPN darlington power transistor (see text)

CapacitorsC1 = 470uF, 16V electrolyticC2 = 10uF, 16V electrolyticC3 = For lab model: 2uF/16V, for Fence Charger: 10uF/16V electrolytic, axial (see text)C4 = 0.27 uF, 400V, filmC5 = 1000pF ceramic diskC6 = 0.01uF ceramic disk

ResistorsR1,R7 = 100 ohm R2 = Selected (see text)R3,R8 = 10K R6 = For lab model: 470 ohms, for Fence Charger: 150 ohms R9 = 2.5 megohm pot (see text)

Additional Parts and Materials T1 = For lab model: Wells C1819 or similar ignition coil; 1.6 ohm primary, 10K secondary. For fence charger: 12V/1A transformer (see text)NE1 = Neon glow lamp; type NE23 or equivalent I1 = 12V/2A, automotive bulb, type 1156 or equivalent

Cabinet or case, PCB, solder lugs of various gauge with internal teeth, cable topower supply #14 to #18 gauge zip cord or whatever suits, spacers, screws, nuts, lockwashers, hookup wire, cable ties, solder, etc.

Additional parts for the fence charger only: two battery clips, Mueller #46C or the like; 1/2-inch pipe, 1-1/2 inch larger nipple, coupling, etc., for grounding system.Circuit Construction:It is up to you how to house this project and the type of material to buy. You may choose to build either version of the project in whatever kind of cabinet suits your needs. If you decide to use wire-wrap construction however, the ground bus and all connections in the power-amplifier circuit should be made with wire no smaller than #24 gauge. In the author's prototypes, power transistor Q3 stands off the circuit board; but if space limitations permit, a slight margin of safety is affordable by bolting it down flat so that the circuit board provides a measure of heat dissipation.Omit R2 from the circuit board and don't connect the supply conductor to the plus end of T1 until ready to fire up. Also, leave the secondary leads unconnected for the fence charger.

In planning chassis layout, keep high-voltage output conductors well away from the circuit board, especially in the version using an ignition coil as output transformer. A metallic or otherwise conductive cabinet must be connected to the circuit common. Since a 30KV pulse is capable of jumping a 1-inch gap, however, you may have some difficulty finding a feedthrough insulator big enough to handle the high-voltage conductor. One way to meet that requirement is to use a spark-plug wire, which may be passed through the cabinet wall using only a grommet to prevent chafing. Or the neck of the coil itself may be used as a feedthrough device, as in the author's mode of construction.

Lab Cabinet Loading:If you are using the author's recommended cabinet, situate the circuit board in the left end of its bottom. The board itself can be used as a template for drilling the four mounting holes in the bottom of the cabinet. Mount the board-assembly on four 7/16-inch metal spacers. The conductive coating in the cabinet bottom may be grounded with a solder lug placed under one of the screws securing the board to a spacer.For variable-frequency or lab model, situate the 'rate' control R9 in the clear-plastic front panel. Bring the power cable into the cabinet through the hole in the bottom rear, using a suitable grommet.The coil mounts on a platform toward the other end and is secure with a hose clamp. Using the coil called out in the parts list, some filing of the platform is required. The coil case must be grounded or internal arcing may occur. Do not depend on casual contact between the coil case and the conductive coating. A grounding connection can be made by inserting an internal-tooth solder lug between the clamp and oil case. At its base, the coil is stopped by its neck passing through a hole drilled in the end of the cabinet top. Hence, it's not likely to come loose with normal handling.At the free end of spark-pug wire install an alligator clip or other suitable connector. At the other end, first slide the coil nipple onto the wire, and then install the coil clip.Important: to preclude arcing, solder the end of the wire to the clip. Push it into the coil neck and slip the nipple into place. When the top is installed later, the nipple provides a tight seal.

Fence Charger Version:Construction of the fence-charger version is somewhat simplified by less-stringent needs for insulation and by the more conventional mounting means for T1. Whatever chassis layout scheme you employ, however, the Earth grounding requirements described above also apply to this model: If you use a conductive cabinet, it must be connected to the circuit Earth, and so must the case of T1. Don't forget that a means must be provided to connect that common to an external ground.In the author's model of the fence charger, T1 is mounted in the cabinet bottom. To ensure a good connection to the transformer case, first scrape any varnish or wax from the mounting flanges. Then mount with 1/2-inch metal standoffs and 8-32 hardware. Use two or three solder lugs as required for various grounding connections.Mount a ceramic feedthrough insulator in the middle of the platform for fence connecting. The underside of the platform comprises a recess which, in an outdoor installation, keeps the output end of the insulator clean and dry.The chimney referred to earlier provides the means for connection to an external ground. A pipe nipple and coupling are required. First solder a length of hookup wire to the inside of

the nipple. A hot iron (say 200 watts) is required for good wetting. Loosely engage the coupling to the nipple; and passing the wire up through the chimney, screw the nipple into the opening by turning the coupling. The nipple may engage the coupling as it engages the chimney. Although the chimney hole is not threaded, the nipple will nevertheless seat securely. Turn the coupling until it is tight up against the bottom of the cabinet. If desired, apply super glue sparingly around top edge of the nipple, bonding it permanently to the chimney. Now, if you later need to remove the coupling for any reason, the nipple will remain in place. Solder other end of the wire to common at the circuit board or at one end of the lugs on the transformer flanges.

High-Voltage Attenuator:Before proceeding with test and adjustment, you may wish to provide yourself with some means for measuring voltage pulses beyond the range of the oscilloscope. To that end, you can build a 90-mega-ohm attenuator, as shown in Fig. 2. When used with a standard 10-mega ohm probe, the device extends the vertical range of your scope by a factor of ten.The attenuator consists of nine 10-mega-ohm

resistors connected in series. A length of spark-plug wire provides support for the resistor array and also serves to introduce distributed capacitance for AC equalization. To preclude arcing, each end should extend an inch or two beyond the terminal.Once you have commissioned your pulse generator or fence charger, you can fine tune the attenuator by adjusting the bus-wire gimmicks at either end of the spark-plug wire. That is

most easily done by generating a high-voltage pulse within the range of your oscilloscope (say 1600 volts peak), measuring with only the 10-mega ohm probe; then, trimming the length of the gimmicks to give the same deflection with the probe connected to the 90-meg attenuator (setting the sensitivity 10 times higher, of course).

Selecting R2:We had advised you during construction to omit one connection to the primary of T1 so that you can now select R2 without energizing the power amplifier. Using clip leads, first connect typical value shown in the parts list. Then connect your 'scope to the junction of R6 and R7, and apply power.For the lab pulse-generator version, now set the 'RATE' control to maximum frequency and select a value for R2 which gives a repetition rate of about 20Hz. For the fence-charger model, select a value which gives the desired rate, but no higher than 60 times per minute. Remember that the slower the rate, the longer between recharging.Now turn the supply off and add the missing wire to the power-amplifier circuit. In the author's lab-generator chassis layout, it is necessary to first loosen the coil in order to free the circuit board. If you plan to test the unit with the circuit board loose, be sure to temporarily replace the lugs grounding the coil case and cabinet. Place a cardboard sheet under the circuit board to insulate it from accidental contact with the cabinet coating, etc.. The unit is now ready for a performance test.

Testing:Connect the high-voltage output to the 90-meg probe or whatever instrument you wish to use to observe the high-voltage pulse. Turn the power supply on and gradually increase the voltage (adjusting the lab-generator rate as desired), synchronizing the 'scope to display the largest excursion. (When you don't know exactly what to expect, it's easy to be fooled into syncing on the backswing or some other minor lobe.)The unit should start working at a supply voltage of 1.5 to 3 volts, but it will shut itself down if you vary the voltage too abruptly. If that happens, just tune the power off and then back on again.At a 12-volt input you should get a pulse of about 20 to 30Kv pk from the lab generator or 3.5 to 5Kv pk from the fence charger. In the latter version, proceed as follows to decide which secondary lead should be grounded:1. Turn power off and disconnect scope from both ends. Turn power back on, and using an insulated tool (to avoid getting zapped), bring each end in turn to the transformer case, leaving the opposite end free. One will probably draw a small arc and the other won't.2. Turn power off and ground the one which drew the smaller arc. Connect the other to the output feedthrough.3. Reconnect the scope, apply power, observe polarity of output pulse. If you get a positive pulse, reverse the primary connections. A negative pulse jumps a longer gap from a small object (the fence wire) to a larger one (the victim) than does a positive pulse (believe it or

not).

If you wish to view the current pulse, temporarily hook 0.1 to 0.2-ohm resistor in series with the negative power-supply lead, and connect a 'scope across it (being careful to avoid ground loops, as can arise through test connections or via the power-line safety ground). With fence-charger option, if possible, simulate 1-mile wire by connecting a 0.015-uF, 2000-WVDC capacitor across its output. A rising waveform characteristic of an

inductor charging should be obtained--the abrupt drop at its trailing edge of course representing the cutoff of Q3 and the generation of the high-voltage pulse.With the lab-generator version, dwell is not critical thanks to the relatively low inductance of the typical ignition-coil primary. In the fence-charger option, however, primary inductance will probably be much higher and will vary considerably upon your choice of transformer. 3. shows the current waveform typical of such a primary. If it ends too soon, that is before the filed has reached its steady-state value (A), then maximum output capability cannot be attained. If it ends too late (B), then average current consumption is higher than necessary. To get optimum results (C), adjust the width by changing R6 as needed.If you know the exact value of the small resistor, given the peak voltage appearing across it you can now calculate peak current (I=E/R). A typical value is 4 to 6 amps.

Buttoning Up:Reinstall the circuit board, remembering to replace the lugs which ground the cabinet, pipe coupling, T1, case, etc., and to secure the coil. Test the unit once more, then assemble the cabinet.If you're using the author's recommended cabinet with the pulse-generator option, leave the high-voltage cable and nipple connected to the coil, passing the other end through the hole in the cabinet top as you bring the top into place. Slide the front panel up into the cabinet top. Now, close the cabinet by swinging the left side down. Moderate force is required to push the coil nipple into the hole. Make sure tongues in the cabinet top engage the mating slots in the bottom, and hold it together with one hand while installing the cabinet hardware with the other. Turn the five bottom screws snug, but not tight.Cabinet assembly of the fence-charger version is easier because you don't have to cope with the coil neck or connections to the front-panel potentiometer. For outdoor use, however, you will have to caulk seams against the weather. Silicone rubber is good for that purpose because it can later be peeled off if servicing becomes necessary. Arcrylic rubber makes a better seal, but because it sticks more tenaciously, it makes later disassembly more difficult.

Carefully apply a very thin bead first along the inside edges of the opening in the top front, and install the front panel. Then, again very carefully and sparingly, apply a bead along the slot in the cabinet bottom; and finally, assemble the top and bottom. Depending on your skill in the application, there may be some squishing around the seams. Surplus material around the outsde can be peeled off later, after the sealand has set.

Installation and Operation:For maximum safety, you should, if feasible, connect one side of the lab-generator power supply to Earth ground. If not, then be sure to provide a return path for the spark to one of the power-supply leads. Set the "RATE" control to get the desired rate, and the power-supply voltage to get the desired output potential. If the output is not excessively loaded, the small in-circuit neon lamp flashes with each pulse. The auto lamp may glow dimly when the rate is set near its upper limit, but otherwise it should never light during normal operation. It does light brightly to warn you when the power leads are reversed or if there is an internal short.If you need one pulse at a time, or bursts of pulses, connect a pushbutton or momentary switch in series with one of the power-supply leads.If you have trouble getting lower output voltages, but not higher, the spark-plug cable may have pulled loose. When that happens, high voltage settings give what appears to be normal performance because the spark path is completer by jumping within the neck of the coil; while at the lowers voltage settings it appears not to be working at all. If that difficulty is encountered, pull the cable out, inspect the solder joints, then simply push it back into the coil.Using the author's cabinet and construction techniques, the fence-charger ground connection is made through the pipe fittings sticking out of the bottom end of the chimney. An Earth-ground means is provided by an ordinary 1/2-inch water pipe. The length should be chosen to permit the pipe to be driven at least 3ft deep, but the deeper the better, depending on estimated conductivity of the soil; with enough pipe rising above ground to place the unit at a comfortable viewing level. Thus a pipe of at least 7ft is required. A more effective ground can be had by adding salt to the soil.Temporarily screw a pipe cap onto top end so as to protect the threads during hammering operation. Pound it into the ground, remove the cap, and screw the fence-charger assembly onto the end. Connect the fence and battery to the unit.The neon lamp flashes with each pulse to assure you that everything is working okay, except in absolute darkness, since a few photons of light are necessary to prime the neon. That apparent drawback, however, has the definite earmarks of an advantage because when it's pitch black the unit cannot call itself to the attention of an interloper.

Jacob's Ladder

"Build this exciting Jacob's Ladder and watch electric arcs ascend the ladder and evaporate in space. It works from a clever 12,000-volt power supply. Author Robert

Iannini."

 Re-written by Tony van Roon (VA3AVR)

People have long been fascinated by electric arcs--and perhaps put off by them. They show up as lightning, Tesla coil discharges, and long sparks that sting as you reach for the doorknob on a cold, dry, winter day. This Jacob's Ladder project turns electric arcs into a dramatic but harmless conversation piece.If you build this project, you'll lean how a simple power supply operating from the 120-volt AC line can produce 12,000 volts. In addition to powering the Jacob's Ladder, the supply can power plasma displays, and it has even powered a light-duty, bench-type spot welder.Perhaps you would like to know the origin of the term Jacob's Ladder. The Bible tells the story of Jacob's dream about a ladder that extended from earth to heaven. Jacob, the son of Isaac, was the father of the founders of the twelve tribes of Israel. Among sailors, however, a Jacob's Ladder is a long rope ladder that is hung over the side of a ship so the harbor pilot can climb aboard.

Climbing Arcs:The power supply for this project forms electric arcs across two diverging stainless steel strips mounted in a protected case. The 16-inch long strips are mounted on insulating Teflon blocks to eliminate possible leakage. The stainless steel strips are angled with respect to each other so that the arcs form at the edges of the strips that are separated by about 3/16 inch at their bases but the strips diverge to a distance of about 2 inches at their upper ends.The strips form a gap in the secondary winding of the output transformer. After power is turned on, the air dielectric breaks down due to the "almost" short-circuit state across the lower end of the gap, and an electric arc is formed.As the arc heats up, thermal convection causes the arc to rise up the vee-shaped "ladder". As the plasma arc ascends the ladder, its length in creases, thereby increasing the arc's dynamic resistance and thus increasing power consumption and heat. This causes the arc to stretch as it rises and extinguish when it reaches the top of the ladder. When the arc extinguishes, the transformer output momentarily exists in an open circuit state until the breakdown of the air dielectric produces another arc at the base of the ladder and the sequence repeats.The power supply for the Jacob's Ladder contains circuitry to protect persons and property

from electrical shock or fire hazard if the ladder strips should be shorted accidentally when the ladder is operating.

Parts List:All resistors are 1/4W, 10%, unless otherwise indicated. R1 = 0.47 ohm, 2 watt R2 = 82 ohm, 2 watt R3 = 2K, PC mount trimmerR4,R8,R10,R12 = 1K R5 = 10K, PC mount trimmer R6 = 10 ohms, 1/4 watt R7,R9 = 27 ohms R11 = 220 ohms

Capacitors: C1,C2 = 0.01uF, 1000V, ceramic C3 = 390uF, 200V, electrolytic C4 = 2.2uF, 250V, metalized polyester C5 = 1000uF, 25V, electrolytic C6 = 0.003uF, 50V, polyester film C7 = 0.01uF, 50V, ceramic C8 = 1.5uF, 100V, metalized polyesterC9,C10 = 1.2uF, 400V, metalized polyester

Semiconductors:

BR1 = bridge rectifier, 4A, SIPD1,D2 = 1N4007, 1000V, 1A, diode D3 = 1N914, silicon signal diode D4-D7 = 1N4735, 6.2V, 1W SCR1 = 0.8A, 200V, sensitive gate, TO-92, Teccor EC103B1 or equivalent Q1 = 2N2222, NPN transistor Q2 = 2N2907, PNP transistorQ3,Q4 = IRF640, N-channel power MOSFET, 200V, 10A, Intern'l Rectifier or equiv. IC1 = 555 timer/oscillator

Magnetics:T1 = Driver transformer, 30 turns primary, 60 turns secondary (see text)T2 = Output transformer, half bridge, 32 turns pri., 2500 turns sec. (see text)

Other Components:S1 = Switch , SPST, panel mount, 10A, pull chainF1 = Fuse, 3A, slow-blow

Miscellaneous:PCB or perforated board (see text); U-chassis (see text); mirror; metallized plastic (see text); transparent plastic covers (see text; L-Panel (see text);stainless steel strips, 0.060-inch thick; 18-1/2 inches (see text) insulating blocks (see text); 2-feet high-voltage wire, 15 kilo-volt rating; 3-wire power cord with line plug; fuse holder; phenolic transformer insulator (see text); hookup wire; miscellaneous nuts, screws; rubber feet (4); linecord grommet; silicone grease; TO-220 mica washers; solder.

Notes:The following parts and kits are available from Innovation Unlimited, Box 716, Amherst, N.H. 03031; Telephone 603-673-4730 or FAX 603-672-5405: Kit of electronic components and circuit board, less transformers--$69.50 Assembled and tested electronic circuit board--$89.50 Assembled and tested driver transformer T1--$9.50 Cores and bobbins for driver transformer T1--$4.50 Assembled and tested high-voltage transformer T2--$24.50 Cores, bobbins, and potting cap for high-voltage transformer--$14.50 High-voltage wire (15KV)--$0.50/foot Teflon insulating blocks (2 required)--$5.00

(Tony's comment: Prices for the above are copied the way they were published in "Electronics Now" and may not be accurate anymore since dated from 1995.Also, although Innovation Unlimited still exists, there is no guarantee they are still selling the kits.)

12,000 Volt Supply:The operation of the Jacob's Ladder depends on the current limited power supply that delivers 12,000 volts at 40 milliamperes from the 120 volt AC line. Refer to the schematic diagram of Fig. 1. The full-wave bridge BR1 rectifies the 120 volt AC line input, and resistor R1 limits the DC charging current of capacitor C3 to a safe value. The Jacob's Ladder project is powered by 150 to 160 volts DC derived from the 120 volt AC line.The drive circuit power is obtained by dropping the 120 volt AC line through capacitor C4 and current limiting resistor R2. Diodes D1 and D2 alternately conduct only in the positive direction, and their DC output pulses are integrated by filter capacitor C5. Zener diodes D4 and D5 regulate these DC pulses to peak values of 15 volts DC.Capacitor C4 and resistor R2 present a complex impedance so that most of the AC line voltage is dropped across the reactance. This configuration eliminated the waste of real power and heat losses that would have occurred by dropping the line voltage with only a resistor.The 555 timer IC1 is configured as a square-wave oscillator. The output frequency of its square waves is determined by the setting of the trimmer potentiometer R5 and capacitor C6. The frequency is is about 25 kHz for the values of R5 and C6 shown in Fig. 1. Resistor R12 limits the high-frequency setting to an acceptable value. Potentiometer R5 can be used to adjust the circuit's power output. Increasing the frequency reduces the circuit's output by increasing the inductive reactance of the transformer leakage inductance.The output of IC1 on output pin 3 appears at the bases of the current "source", NPN transistor Q1 and "sink" PNP transistor Q2. The emitters of this transistor pair are AC-coupled through capacitor C8 and resistor R6 to drive the primary of driver-isolation transformer T1. This drive prevents DC from flowing thought the primary. Resistor R6 dampens any overshoot that results from transformer T1's leakage inductance.The scheme provides a satisfactory source for driving the high gate-to-source capacitance of the two NPN switching power MOSFETs, Q3 and Q4. Transformer T1 is wound on a high permeability core with as few turns as possible to eliminate leakage inductance.The gate circuits of MOSFETs Q3 and Q4 contain 27-ohm resistors (R7 and R9) to slow their switching times. This eliminates possible parasitic oscillations that could occur if the MOSFETs were switched at their speed limit.Output transformer T2 has a half-bridge configuration so that MOSFETs Q3 and Q4 are only subjected to half of the rectified DC line voltage, or about 80 volts. Assuming that the voltage midway between capacitors C9 and C10 is about half of 160 volts (or about 80 volts), when Q3 turns on, the charge on C9 causes current to flow through T2 in one direction.When Q3 turns off, Q4 turns on, dumping the charge on C10 through T2 in the opposite direction. This drives the magnetic flux of T2 evenly and symmetrically, making full use of T2's core capability. The primary of output transformer T2 contains 32 turns, but its secondary contains 2500 turns. The ratio of these turns is approximately 1 to 78. When multiplied by the rectified line voltage of 160 volts DC, an output of about 12,000 volts peak volts is obtained across the secondary.This 12,000 volt output is the peak open-circuit voltage of the system, and it produces a short-circuit current of approximately 40 milliamperes. This current is limited by the leakage inductance caused by the loose magnetic coupling between the primary and secondary circuits of transformer T2. This leakage inductance can be controlled to some extent by placing air gaps between the cores, changing the reluctance of the magnetic

circuit.

Safety Provisions:Because this project is operated from the 120 volt AC line, fault and safety shutdown provisions are included. They are provided by silicon controlled rectifier SCR1 connected as shown in Fig. 1 with its anode in series with diode D3. When the gate current reaches a specified threshold, the SCR is triggered on and latched by holding current through resistor R4. Trigger pin 2 and Threshold pin 6 of IC1 are now clamped to ground, thus preventing oscillation and turning off the circuit.The signal current for the gate of SCR1 is obtained from the capacitive connection to the actual core of the output transformer T2. This connection is made by winding three to four turns of insulated hookup wire around the core of transformer T2. In effect, it is a capacitive wire pick-up probe. As long as output power is flowing between the output connections of T2, the Jacob's Ladder will continue to operate.If, for some reason, one of the output leads (vee strips) is grounded, a return current is forced to flow by capacitive action between the core of transformer T2 through the wrapped-wire pick-up probe. This current then turns on SCR1, shutting down the Jacob's Ladder.

Building the Circuit:The high-voltage power supply circuitry for the Jacob's Ladder can be built by point-to-point wiring methods on a 5-1/2X2-1/4 inch piece of standard perforated circuit boards (holes spaced 0.10 inch on centers) or on a circuit board available from the source given in the Parts List. Drill mounting holes in the four corners of the circuit board before inserting any electronic components.

All of the electronic components with the exception of transformers T1 and T2 are standard, off-the-shelf components available from electronics stores and mail-order distributors. However, the transformers must be custom wound. Both transformers, completely wound and tested, are available from the source given in the Parts List. Alternatively, you can wind your own transformers if you have some experience in doing this. Some useful information on winding these transformers and material selection is given

later in this article under the heading, "Winding the Transformers."Refer to the schematic in Fig. 1 and parts layout diagram Fig. 2. The parts layout diagram gives the approximate locations of all components except for switch S1 and transformer T2, which are off-board components. There is nothing critical about parts placement, and suggest layout of Fig. 2 is based on keeping interconnecting wiring as short as practical. Be sure to make the gate connection go MOSFETs Q3 and Q4 as short and direct as possible.Begin by inserting and soldering all components except MOSFETs Q3 and Q4. Observe the correct polarities for all silicon diodes (D1 to D3), Zener diodes (D4 and D5), and electrolytic capacitors (C3 and C5. If you wire point-to-point, do not trim the leads of the components until you have made use of as many excess leads lengths as is practical to form interconnections between components.Then insert the TO-220 packaged MOSFETs Q3 and Q4 close to the outer edges of the circuit board in the locations shown in Fig. 2, with their metal tabs are facing outward. In a later step, the tabs of Q3 and Q4 will be fastened to the sides of a U-shaped channel that functions both as a heat sink and as a support for the circuit board.Carefully examen all the electronic components on the board to be sure that they are correctly placed and oriented. Examen all solder joints to verify that there are no inadvertent solder bridges or cold solder joints (a joint soldered too fast and does not adhere properly). Make any corrections at this time before proceeding. Then set the completed circuit board aside.

Product Enclosure:Figure 3 illustrates the author's enclosure for the Jacob's Ladder project. It was designed to meet two objectives: 1. to meet all reasonable safety requirements by providing adequate insulation between people and flammable materials and the enclosed high-voltage circuitry, while at the same time protecting the circuitry form dust and dirt. 2. to be simple enough to be made by persons with minimal carpentry skills form materials readily available at hardware and home-improvement stores.Many variations on the author's enclosure design are possible including changes in exterior and interior dimensions and the substitution of more expensive wood for the framing. However, it is imperative that all provisions for ventilating both the circuitry and the vee "ladder" to dissipate any heat buildup be followed, but make sure that those spaces are not large enough to admit fingers or the small hands of curious children.The overall case dimensions are 24 x 12.5 x 4 inches. The closed H-shaped frame was

made from 3/4-inch thick x 4-inch wide soft wood. Slots that are 1/8-inch wide and 1/4 deep were milled 1/8-inch in from each edge of the inside surfaces of the frame members to accommodate protective transparent plastic covers on the front side and a metalized plastic mirror on the back side. (These protective sheets could be fastened directly to the case edges with screws.)The bottom of the case and the back of the lower circuit/transformer compartment is covered by an L-shaped aluminum plate that serves as the vertical support for the circuit board and output transformer. Holes drilled in the bottom of this plate permit circuit ventilation and access to the on-board trimmer potentiometer R3 and R5. Another hole id formed in the back of the plate for mounting on-off pull switch S1.Figure 4 provides general information on the sizes and shapes of the principal wood and aluminum parts. Notice the holes drilled in the top member of the frame for cooling the ladder compartment. The author's prototype frame was made by assembling the wooden frame with screws after the clear 1/8-inch plastic front windows and rear mirror were cut to fit the milled slots.The transparent plastic cover for the ladder compartment was cut 1-inch shorter than the inside dimensions of the frame to provide a bottom opening for ventilation. This ventilation slot is important and should be there regardless of any dimensional changes you might want to make in the frame. The cover for the circuit compartment protects that compartment completely. It is transparent plastic in the prototype so that the circuitry could be seen, but it could be opaque.

Project Metalwork:No hole sizes or location dimensions are given here for the enclosure components. Those are left to the builder's judgment. Cut and form the U-shaped aluminum channel from No. 22 gauge sheet aluminum, as shown in Figure 4. Drill hole in both ends of the channel along the centerline. Then, using the drilled holes in the circuit board as a guide, center-punch and drill four holes for mounting the circuit board to the channel. (These can be omitted if you elect to bond the circuit board to the channel with hot plastic glue drops.)Cut the L-shaped panel as shown in Figure 4 from No 22 gauge sheet aluminum. Before bending the front lip of folding the plate, drill 1-inch diameter holes for circuit cooling and access to trimmer potentiometers R3 and R5. Above the fold line, drill another hole for the linecord (powercord), large enough to admit a rubber or plastic grommet, and drill a hole to accommodate chain-pull switch S1. Then bend the flat plate 90° along the fold line and bend up the front lip.Drill two holes evenly spaced within 2 inches of the ends of the stainless steel "ladder" strips, and bend those 2-inch long sections approximately 90° with respect to the rest of the strips. Note: Stainless steel was selected for the ladder strips because the electric arcs will not cause the strips to oxidize or corrode, and tests showed that stainless steel permits easier starting of the arcs than other metals.

Insulator Blocks:The two metal strips that form the "ladder" must be mounted on insulators that have high dielectric strength. The insulators in the prototype were made from Teflon blocks that measure 1-1/4x1x3/4 inch high. This material can be drilled and tapped, and it is strong enough to withstand the heat created by electric arcs. Individual Teflon blocks are available from the source in the Parts List.

Project Assembly:With the completed circuit board inserted in the channel, elevated slightly above the bottom of the channel, mark, centerpunch and drill the holes in each side wall for fastening the tabs of MOSFETs Q3 and Q4. Be sure to deburr and perhaps countersink slightly the holes in the channel so that the tabs on the MOSFETs will be clamped securely against the channel walls. Cut and trim the ends of two 3-inch lengths of insulated, stranded linecord to the circuit board, as shown in Fig. 2, to make the connections with the linecord. Insert and solder the ends of the wires on on-off switch S1.Attach the circuit board to the U-channel with screws and nuts, using several nuts as standoffs to isolate the circuit board from the channel. Align the tabs of MOSFETs Q3 and Q4 with the holes in the sidewalls of the channel, insert insulating mica washers with a film of silicone grease between each tab and the channel walls, and fasten them with screws and nuts.Cut a 2-1/2 inch square of phenolic laminate or circuit board stock between the base of transformer T2 and the bottom of the channel. Bond the transformer to the insulator and channel base with epoxy or hot glue.Drill two holes through the wooden frame member between the two compartments, and insulating blocks. Drill a singe hole in the opposite sides of each block and fasten the ladder as shown in Fig. 3.Then attach the insulation blocks and strips to the frame member with screws. Fasten the bent metal strips so that they are offset by about 30°, as shown in Fig. 3. The base strips are diagonal across the insulator blocks so that the corner edges are separated by about 3/16 inch. The upper ends of the strips should be about 2 inches apart.Fasten the channel with transformer T2 and the circuit board to the L-shaped panel with screws and nuts, as shown in Fig. 3. Complete the installation of switch S1 and the linecord with a grommet, and complete all soldering. Be sure the L-shaped metal panel is hard-wire connected to the earth ground by means of the green wire within the three-wire power-cord. Assemble the enclosure with its plastic covers and aluminum base plate. The Jacob's Ladder is now complete.

Adjusting the Ladder:Carefully examine your work to be sure that there are no inadvertent short circuits of cold solder joints. The circuit is now ready for testing. First, adjust potentiometer R5 as follows:

1. Disconnect one end of R1 to Q3.2. Connect an oscilloscope to the Q4 gate.3. Plug in power cord and turn on power.4. Adjust R5 for a period of 40nS so 15-volt squarewaves are symmetrical.5. Shut off power, reconnect R1, and connect the oscilloscope to the Q4 drain. Turn on power. A near perfect squarewave should appear, and it should remain constant as arcs form and reform. Adjusting procedure for the ground-fault potentiometer R3 to shut off the circuit if there is ground-fault current:1. Turn off power and set wiper of R3 for maximum sensitivity.2. Disconnect a high-voltage lead from a ladder strip, and connect it to ten 1-watt, 100 kilo-ohm resistors in series. (This simulates a 10-milliampere ground current.)3. Apply power and verify that the circuit shuts down. Turn off power, adjust R3 slightly clockwise. Reapply power until high voltage stays on. Note: allow time for C3 to discharge before re-applying power or SCR1 will stay on.Winding the Transformers:Figure 5 is a "footprint" diagram of drive transformer T1 with callouts that can be related to those found on the schematic Fig. 1. The cores and bobbins for this transformer are from Philips (Ferroxcube) Components, Saugerties, NY). The cores are No. E187 made from 3E2A molded ferrite material. The plastic molded bobbins are Part No. E187PCB1-8. These parts are available from the source given in the Parts List.Transformer T1: Wind the first 30 turns trifilar (three wires in parallel) from No. 30 AWG magnet wire and the remaining 30 turns as single wire turns. Solder the ends of the windings to the pins, insert the E-core, and tape the assembly together securely.Transformer T2: The core of transformer is No. 4162S from Samhwa USA, Chatsworth CA, with matching seven segment bobbin, cup and primary bobbin. These parts are also available from the source given in the Parts List.Start winding the secondary bobbin by securing the magnet wire to a pin insulated on the bobbin end and wind between 300 and 400 turns of No. 37 AWG magnet wire on each of seven segments. Snap the cup in place and solder the output leads. Fill the cup with epoxy or RTV Silicone when you are satisfied that the transformer has been wound correctly.Wind eight turns of No. 30 twisted wires on the primary bobbin and tape the windings in place. Form the air gap of the primary section with 0.005-inch thick Mylar tape and form the air gap for the secondary section with 0.010-inch thick Mylar tape. Tape of clamp the two sections together with a heavy rubber band.

Parts List:All resistors are 1/4-watt, 10%, unless otherwise noted R1 = 0.47 ohms, 2 Watt R2 = 82 ohms, 2 Watt R3 = 2K, trimmer potentiometerR4,R8,R10,R12 = 1K R5 = 10K R6 = 10 ohms

R7,R9 = 27 ohms R11 = 220 ohms

Capacitors: C1 = 0.022uF, 50WVDC metalized filmC3-C12 = 0.001uF, 2000WVDC ceramic disk C13 = 220uF, 25V, electrolytic C14 = 4700uF, 35WVDC, electrolytic Note: There is no C2.

Semiconductors:D1-D10 = 1N4007, 1A, 1000PIV, silicon rectifiers connected in series (see text) D11 = 1N4007, 1A, 1000PIV, silicon rectifier Q1 = TIP31A, Darlington transistor U1 = MC1458BAL hex, inverting Schmitt trigger, IC BR1 = 6A, 50PIV, full wave bridge rectifier Led1 = Jumbo green light emitting diode

Other Components:Ne1 = Ne2 neon lamp T1 = Ferrite core step-up transformer (see text) T2 = 12 Volt, 2A, power transformerPL1 = 117 volt AC plug with line cordPerfboard materials, enclosure, battery, heat sink, IC sockets, battery, wire,Battery, Battery holder, solder, hardware, etc.Please Note: don't ask for additional information. This is all there is. Don't email me or leave messages in regards to this project in the "Message Forum"; they will be deleted without prior notification. NO I don't sell a kit, NO I don't have a pcb either. The 'suggested' parts lay-out diagram refers to perforated board. Meaning, you do point-to-point wiring and soldering.However, on the positive side, I may try to put a kit together with all parts and maybe a pcb if there is enough interest.

HIGHT VOLTAJE

SPARK GENERATOR CIRCUIT

These somewhat low powered versions shown here are probablyaround 50,000 volts on a slower pulse rate.  

(If they are Built Correctly.)

The main power limitation to these two devices is T1. These are actually minature "Audio Transformers"connected in reverse to step up the 12 volts to around 400 volts, with no load.

These are not ideal parts for this purpose as they don't have the ability to produce the high currentsthat would result in a more sustained spark on the output.

This Medium powered version has a center tapped primary with dual transistors, resulting in amore efficient circuit. For Simplicity and "Off the Shelf", this was the best I could do.

If your an adventurist, you could wind a small transformer for any of these units below.

This would allow for higher efficiency and more current draw.

On the "Low Power" Stun-gun, Current draw is about 80 Ma at 9 volts.

On the "More Power" Stun-gun, Current draw is about 225 Ma at 9 volts.With dual batteries, Better yet, 6 to 8 "AA" cells

Most Commerical Stun Guns, use either a "Spark Gap" or a "Surge Arrester" (Movistor) to control Triggering of T2.

1) These Spark Gaps are just a Cross of two Metal strips.Adjusting them is somewhat Critical and they are NOT very reliable over time.Like Relay Contacts, they get Pit marks and than Fail to work properly.

2) Surge Arresters are made for Fixed Voltages.Athough they are a simple solution, they don't allow for easy tuning of the output spark rate.Mostly they use Movistors rated between 800 to 1400 Volts.

As an alternative to these, I use an "SCR", as these allow for a good & reliable adjustment to trigger T2.The biggest draw-back is finding really high voltage SCR's. The SCR I normally use is rated at 800 Volts @ 0.8 Amps.Thats Not too bad, but a 1000 to 1200 volt rating would be nicer.

My hope is this info is a Help to some of you who just like to play a bit and get a understanding of them.

In No Way Do I Recommend Building these Stun-Guns or the actual use of them for any purpose what so-ever.

I Assume NO LIALIBITY for any resulting actions of those persons who build or use any of these devices!

A Real Misconception about Stun-Guns, Is the Output Voltages.Although this Sounds Good in the Advertizements, It is Current that does the damageand any spark capable of pentrating through the clothing and skin is totally sufficant to do the job.

A blue spark looks pretty and will hurt, but a "YELLOW SPARK" is"MUCH HIGHER CURRENT" and GETS REALLY DEADLY.

A Point to Ponder,   Here is a picture of a 10 inch Diameter Porcelain Insulator!This is the type used on the High Tension Power lines that run through the country side.On a 750,000 volt line, they will use about 35 of these insulators hooked together in a series string.

The "Flash-over Voltage" of this Insulator is 80,000 Volts and that is over a "surface distance" of about  11 inches.

When have you ever seen a 100 KV Stun Gun with even a 10 inch Spark Gap? In Reality, the spark gap determines the "Actual Voltage Available at the probes".With a spark gap of 1 to 2 inches or so, it is No-where near the 100,000 to 750,000 volts that these manufacturers claim.

Stun gun (taser) The stun (also known as taser) can paralyze the attacker with paralyzing electric shock. Brief contact with the stun gun output voltage he gets an electric shock that temporarily paralyzes him to deter further attacks. Prolonged contact with the stun gun output voltage (more than 1s) leads to muscle spasm, the attacker falls to the ground. Up to several minutes he is unable to coordinated movement.

    The stun principle:

Stun gun works as a two-stage voltage converter. The first stage with the high frequency switching transformer increases the voltage of the battery to a higher voltage of a few hundred volts to several kV. This voltage is charging a capacitor. After being charged the capacitor is discharged into the second (pulse) transformer to increase the voltage to approximately 10 - 50kV. (Numbers on the Stun gun as 100 000 V or even 2000 000 V are fictitious, voltage 2 000 000 V would create discharges of more than 2m long - manufacturers are just competing in the silly numbers of volts the general public does not understand.) Repetition rate is about 5 - 40Hz.

    Types of stun guns:

There are 3 basic types: Thyristor (SCR) ones, spark gap ones and multiplier ones. spark gap stun guns are just the cheapest types are very unreliable and ineffective. Thyristor is replaced by a spark gap. Battery voltage is boosted using transistor converter. For the ignition of the spark gap, a higher voltage (at least 1kV) is needed and is therefore sometimes an auxiliary multiplier is attached to the secondary of the first voltage transformer. After charging the capacitor to a voltage sufficient to ignite the spark gap it discharges into the capacitor in the pulse transformer. The principle is similar to the Tesla coil. Thyristor stun guns are more reliable and more efficient - the spark gap is replaced by thyristor (SCR). Capacitor voltage is not so high, just about 250 - 500V. Thyristor is driven by a diac, neon lamp or resistive divider (for thyristor control with sensitive electrode). multiplier stun guns have only one transformer with a higher output voltage, followed by a high-voltage multiplier cascade of diodes and capacitors. Their output is a DC voltage. Thanks to the capacitors in multipliers the sparks are very loud. In direct contact with the skin, however, capacitors are not discharged in pulses, but continuous current flows, which can significantly reduce the effect. It is therefore necessary to only get the electrodes close to the attacker body, but not touch him directly.

    My stun gun:

I chose thyristor (SCR) version. I made a voltage converter with a MOSFET, because "children's" push-pull converters with bipolar transistors used in commercial stun guns have an efficiency of around 20%. The effectiveness of my converter is about 75%. Working frequency is about 80 - 120kHz. As a second stage switch I used a thyristor with a gate driven by 4 glow neon lamps in the series (their ignition voltage is about 95V, a total of 380V). Pulse repetition rate is about 30 - 50Hz. Inverter transformer is on ferrite EE core

with cross-section of the the middle column 20 to 25 mm2. The air gap is in the middle column of the core and is about 0.5 mm thick. Primary has 2x 12 turns of wire diameter of 0.4 mm, a secondary is 700 turns of wire 0.1 mm. Secondary is is wound in several layers, which are isolated from each other - otherwise the wire enamel can break down under such voltage. Secondary polarity must be observed! HV pulse transformer with voltage of many kV can be hard to make. You can use the high voltage transformer for Xenon strobe lamps ingition. I used 2 such transformers with primaries in parallel and secondaries in series. The stun gun has two electrodes: one called test, which are closer to each other. Among them he discharge forms during no-load operation. Discharge limits the maximum voltage and also serves to deter an attacker. Second, the main electrodes facing forward. The distance between them is considerably larger than the distance between the test ones. From those electrodes the current flows into the body of attacking people :). Stun gun can be powered by 6 cells 1.5 V or 6 to 7 cells 1.2 V (NiCd or NiMH). Very suitable are 2 cells of Li-ion or Li-pol connected in series (2x 3.6 - 3.7 V). The stun gun draws a high current around 1.5 A from the battery, so ordinary 9V battery can not be used.

     WARNING! Instructions for the production of this device is intended only to demonstrate the principle of its function. The device is not intended for use on any persons or animals. Output voltage can cause serious injury or death. Capacitors can remain charged even after switching off and disconnecting the battery. The device does not belong to children. All experiments with the stun gun you do at your own risk. The author of this website does not take any responsibility for your harm. You do everything on your own risk and responsibility.

The schematic of the homemade stun gun (taser).

Testing in breadboard

PCBs of the stun gun and the 9V / 400V transformer.

Test the assembled module with attached transformer (transformer is used for ignition of Xe lamp: 190V / 6kV)