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Some New Information for the Wiki

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Some New Information for the Wiki

Unread postAuthor: mark.f » Thu Dec 13, 2007 6:32 pm

When I was looking at the Wiki, I noticed the small section about the internal spark electrodes on a stungun. I am not referring to the test electrodes on the outside, but rather the VERY small spark gap on the INSIDE. The funny thing was, I've been reading a tiny bit about Tesla coils, and this struck me as similar to a generalized tesla coil. The real Wikipedia also supports this theory, saying that they may be run off an oscillator, resonant circuit, and step up transformer.

Basically, I am postulating that a standard stungun makes use of a resonant electronic circuit like a tesla coil, (diagram below), to produce the high voltages relatively quickly. Instead of mains power across the step-up transformer going to the primary circuit, though, you would have something along the lines of a 555 oscillator to produce the proper driving current.

<div align="center"><img src="http://www.markfh11q.net/images/tesla.gif"></div>

Except, the output from the primary circuit would then be used to drive something along the lines of an autotransformer, to step the voltage either up or down, (depending on the primary circuit's output).

What do you electronic geniuses think? I've googled to no end but nothing has any real specific information on the circuitry of a stungun.

EDIT - BUMP. C'mon guys. This actually has quite a bit of relevance. By switching out things like the capacitor in the primary circuit, or the charging transformer, or the control resistors and capacitor on the 555 oscillator, you can change the frequency of the output from the retarded "click click click click click", (~ 5 Hz from my count), to somewhere in the range of a few kilohertz.

This means we can mod a stungun to provide a continuous spark, like a flyback transformer... except with about half the headache, (I still haven't been able to find the primary and secondary ground leads on my flyback. Only the secondary + lead and feedback leads are marked with wires, and there's 12 leads on the bottom. With a few minutes and a multimeter I bet I could find the right leads, but as for now, I'm kind of screwed here. Also need to find a good enough switching transistor. Only type transistors that are available are the MOSFET switching ones, and the crappy power transistors that will burn out in two seconds switching the high-frequency off the feedback.)

I guess I'm going to have to break down and just buy one myself. That throws my plans for ordering a bunch of crap from AllElectronics to make some junk out the window, though.
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Unread postAuthor: jimmy101 » Fri Dec 14, 2007 5:40 pm

You are probably right, tha basic circuitry of a stun gun probably mimics a tesla coil.

So?

BTW, flyback transformers do not supply continous sparks. Usually, when used for their designed purpose, they provide a spark at a frequency of a couple tens of kilohertz with a duty cycle of just a couple percent. In other words, the flyback circuit blinks on and off at a moderate high rate but the high voltage is only present for a very small percent of the time.

What advantage would a high frequency spark have over a single spark? Where are you headed with this?

Doesn't have much applicability to spudguns. If the first spark doesn't ignite the fuel what makes you think the 5,321<sup>st</sup> spark will?

You might be able to tweak the circuit up to give the "continous" spark of a tesla but I suspect you would have to just about change every component in the stun gun to get it to work. Might as well build it from scratch in that case.
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Unread postAuthor: paaiyan » Fri Dec 14, 2007 5:46 pm

Well I wouldn't say you need 5,000 sparks, but sometimes it does take more than one.

Man, I always did think it wold be cool to use a tesla coil as an ignition source...
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Unread postAuthor: mark.f » Sat Dec 15, 2007 8:52 am

I know it doesn't have much of an application, that's why I sort of slipped it into Non-Spudgun Related Discussion. It would be a good idea to put some of this information into the Wiki once we got it confirmed, though.

And I know no spark is really "continuous", you'd have to have some pretty serious direct current to do that. :shock: I usually just say "continuous" once it's past ~30 Hz, because it just might as well be continuous. I know it's not accurate but don't flame me!

And yes, it doesn't have much application... yet. The only thing that really comes to mind would be those "Rambo"-styled hybrids. The ones where you inject too much fuel, hit the continuous spark, and pump in air until it fires.

Paaiyan, I've ordered a 2,000 VAC neon sign transformer for my power source. I'm hoping to have some sort of half-ass working tesla coil done by a few weeks after I get it, (other parts can be salvaged from other projects). Again, jimmy, thanks for pointing me to All Electronics. Where else can you get a NST for 10 bucks? :D Even if running a tesla coil off of it doesn't work, I can still use the primary circuit to chop the sine-wave output to square wave and run an ignition coil off it, or just use it by itself for spark gaps a little under a millimeter, (2/3rds of a millimeter, by my calculations).

Anyways, just some thoughts. I'd have to order a "standard" stungun, (if there is such a thing), and take it apart before reaching any conclusions, though.
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Unread postAuthor: jimmy101 » Sat Dec 15, 2007 2:34 pm

markfh11q go for it.

Any continous high voltage spark is fun.

I suspect the generic (i.e., cheap) stungun won't work for what you have in mind. They are just too fragile. If they are operated continously for more than a few seconds they tend to fry themselves.

Perhaps add a good sized heat sink to the main transistor (or SCR, or MOSFET or whatever it uses) and perhaps even a small fan to keep things cool enough.
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