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# Microcontroller based Stun Gun (Exercise)

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#### Gandledorf

##### New Member
As an exercise, to see if I actually understand some of the things I've been learning from all of the wonderful help I've been recieveing here (and I cannot thank you enough for it), I tried to first: A, figure out exactly why the stun gun on the projects page works (mainly because of the transformer), and B, redesign the schematic for use with a uC.

Here is my result, could someone please "grade" me on my understanding of this exercise, and point out my mistakes (which I am sure I made).

In the original circuit, the 555 timer was set to generate a pulse of around 60, or 220Hz, depending on the capacitor (whether it was .1uF or .47uF respectively), which drove the transistor, causing the transformer to step up the voltage by a factor of 200, from 9V to 1800V (minus some loss), and step down the current to 1/200 of it's original value (which was what? I couldn't find a current limiter).

In my version, I take a 9V battery, and run it through a 5V regulator. My processor is switched on and generates a 60Hz signal when the trigger is depressed. This signal is run through a current limiting resistor, and then through a transformer, where the voltage is stepped up by a factor of 230 to 1150V, and the current is stepped down by a factor of 230 from 2.5mA to .01mA. A 1M pot on the other end can be used to vary the voltage between 1150V and 10V.

Microcontroller based Stun Gun

Hi Gandledorf,

1st, I think yer circuit looks good to me. But I'm just wondering why U desire to use a micrprocessor instead of a 555? :-/ It just seems to be such a waste of a micrprocessor. In fact, U probably don't even need a 555 to make this work, but that's another story. Other than the issue of the micrprocessor, the circuit looks ok thus far.

Cheerz!

Bob

As I said, I'm doing this more as an excercise, than as a real project, though I may build one for my wife anyway, as she doesn't like being out alone in our neighborhood, and I have some spare uC's lying around.

Don't know much about stun guns! However, I doubt that you would be able to generate any kind of high (KV range) voltage using audio-type impedance matching transformers.

I would recommend a two step process. First use a small mains type transformer (a 240V/120 V primary to 3 - 6V secondary would be nice) operated in reverse to generate about 240V using your 60 Hz source, and a suitable transistor driver). After rectification, you could try feeding the high DC voltage to a trigger coil of the type used to trigger Xenon flash tubes with a suitable driver circuit again (typically SCR and capacitor). That should give you a pulses of a few KV's.

Don't know much about stun guns! However, I doubt that you would be able to generate any kind of high (KV range) voltage using audio-type impedance matching transformers.

I would recommend a two step process. First use a small mains type transformer (a 240V/120 V primary to 3 - 6V secondary would be nice) operated in reverse to generate about 240V using your 60 Hz source, and a suitable transistor driver). After rectification, you could try feeding the high DC voltage to a trigger coil of the type used to trigger Xenon flash tubes with a suitable driver circuit again (typically SCR and capacitor). That should give you a pulses of a few KV's.

Re: Microcontroller based Stun Gun

B-o-b said:
Hi Gandledorf,

1st, I think yer circuit looks good to me. But I'm just wondering why U desire to use a micrprocessor instead of a 555? :-/ It just seems to be such a waste of a micrprocessor. In fact, U probably don't even need a 555 to make this work, but that's another story. Other than the issue of the micrprocessor, the circuit looks ok thus far.

Cheerz!

Bob

i havnt looked at the other schematic yet, but i'm guessing the 555 timer is used to make an oscillating output to stun the victom... a sin signal (or square) would be alot safer then a DC going into someone... for one, the DC would hold them to the gun and shock them until the person using the gun let off the trigger (then again, maybe that's what you want to do :twisted: ), whereas the AC will blow them away, but still give quite a shock.

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