Shocknife

[Dudeman]

I saw a segment on TV the other day about a new training device. It is a plastic knife with a hunk of copper running it's length. It is powered by a 9V battery and gives a nasty shock when touched. I'd like to try and build something similar seeing as I don't want to spend $400 on one. I saw the schematic for a stun gun, but would you be able to replace a large piece of Al or Cu for the 2 electrodes? Would that burn up the circuit? It has been about 12 years since I worked at the component level, and I think I've forgotten just about everything. I can't even remember the code for resistors! (I looked it up though)

Thanks for any assistance.

 

[Dudeman]

Everyone correct me if I'm wrong.

After closer examination (www.shocknife.com) it looks like there are 2 plates approx. 1/4 inch apart. That answers my question regarding a single plate closing the circuit and burning it out. Now my only concern is the power output. I need this to put out enough power to make you recoil; not nearly the ouput af a standard stun gun. No one would want to use it as a training device then. What if I used a smaller transformer?

 

[DigiTan]

Heh heh, talk about adding injury to injury. :lol:

Since the shock is more effective in longer durations, I would monitor the load somehow (ie: "Victim) and impose some maximum shock time using a timer to interrupt the power source. I'd still be afraid to use it though.

 

[Dudeman]

What size transformer and rheostat would you suggest? The schematic has a 1K to 200K audio transformer, and a 1M (?) rheostat.

Again, I'm not really interested causing REAL pain. I want it the hurt a bit, but I'd rather not pee on myself.

 

[DigiTan]

For that it's tough to recommend. I estimated my store-bought taser had a turns ratio of 1:285 to 1:200 which was stepping up discharges from a 350-volt spark gap oscillator. [Assuming the shock voltage was the 100KV it was advertised as]. The transformer would have to built for the high-voltage taser application or else the secondary coil will experience dielectric breakdown (among other problems). The only retail vendor I know of that caters to this spec is amazing1.com but theirs is "only" a 45kV transformer.

The frequency on your oscillator also has to be controlled to operate in the LF region (50kHz is typical) or else it becomes highly dangerous. Additionally, the oscillator has to be current-limited to avoid moving a hazardous charge--even for small load resistances, which I'm in the process of researching. There's a lot of controversy involving tasers (most of it scaremongering), so my best advice is to just take a professionally-built taser and create a supply cut-off switch.

 

[Someone Electro]

I once built an flyback oscilator.Whith an transformer made out of wire wound around an ferite rod.The output was about 10W and preaty shocking to toch.That was at ultransonic AC so if you make it DC it will be much more shocking.Also you can make the victim hold it how much you want becose if you run DC trough his arm he wont be able to let it go,until you thurn off the curent.

9V batery wont last long.Since you will be drawing a lot of curent from it.