Build Your Own Stun Gun

mariox19 writes "Wondering what to do with your disposable camera when you're finished with it? TechTV has an article describing how to reach out and zap someone with a home-made stun gun. I discovered the link via Bruce Schneier's latest Cryptogram, where Schneier half-jokingly warns not to let airport security find out about this, lest (in their 'wisdom') they ban cameras along with nail clippers."

Comments

Wow

[General Sherman]

I wonder if tasers are ever going to become controlled devices.

Re:Wow

[JWSmythe]

At an automotive shop I used to pseudo-work at, they used to joke about taking the capacitor from old distributors, and just tossing them to newbie mechanics, teaching them not to ever catch something thrown at them. :)

The disposable camera route seems kind of silly. Most people who would attempt this should have enough parts laying around their house to build one. I believe an old PC power supply would have the required components, or it should only cost a couple bucks at Radio Shack to build one.

I like your softball idea, but it would seem to pose too much of a chance of not hitting the electrodes correctly. There's so much chance they'd catch the ball wrong, and both electrodes would hit one hand and they'd only say "Ow!" before beating the crap out of you.

Re:Wow

[blincoln]

I wonder if tasers are ever going to become controlled devices.

Just to be irritatingly picky, I'm going to point out that there's a difference between a taser and a stun gun.

"Taser" is actually an acronym for "Thomas A. Smith Electric Rifle," and is a handheld weapon which fires barbs into its target with compressed air. The barbs are tethered to the gun with wires which transmit the electricity.

A stun "gun" is a handheld device that has two short metal probs that you physically touch to the target, like a tiny cattle prod.

A true taser has the advantage of being able to be used from a distance, so if you are a police officer dealing with e.g. a crazy person swinging a sword in public and don't want to gun them down, you can try the taser first.

Could they get banned at airports?

[wheresdrew]

Sure. Different airports ban different things. On a recent trip from Seoul to Tokyo, I had a pack of Duracell AA batteries confiscated by security at Gimpo airport in Seoul. Not rechargables or anything special like that, just plain alkaline AAs, still in the package.

However, when I was leaving Japan I noticed security at Haneda had no such rules. In fact, you could buy both alkaline and lithium batteries at the shops beyond the security checkpoint there.

I've yet to get an explanation for why plain batteries are considered a security risk.

Re:Could they get banned at airports?

[LostCluster]

I've yet to get an explanation for why plain batteries are considered a security risk.

I think you just got it. Batteries represent stored electicity... and they can't exactly trust that the battery's voltage is really what's on the label if you don't have a device that you can show properly operates.

Sure, that's paranoid... but that's what the security people are in the business of doing.

bah - here's a project for yah

[Anonymous Coward]

Wires? In the 21st century, who needs wires?

http://www.geocities.com/Area51/Shadowlands/6583 /p roject431.html

Now off to Ebay for an excimer laser or 2, a white lab-coat, goggles and some nair...

capcaitors aren't full...

[focitrixilous P]

I remember when my physics teacher showed us a huge capacitor bank. Chared it up and discharged around a columb to a paper clip. No warning of loudness at all, just asked someone to turn off the lights and BLAM! Dischared! It was pretty cool. If only cameras had such potential. Looks like another weapon is going to be added to my garage armory. (blow gun that shoots nail darts, potato gun, and now this.) I should probably AC this, but let the feds take them away. I can always make more. Unless nails, PVC pipe and paper are banned, that is.

Re:Way back...

[metlin]

Actually, if you can have any kind of discharge, you can build a primitive coil gun/sten gun.

In my freshman year of EE, we used to build capacitor banks and use them to power our coil guns.

And another thing to do is to use Flyback drivers to discharge and use them to power hi-voltage stuff. Ofcourse, this knowledge came to us much later, but was useful neverthless :)

With a little bit of expertise, you can build a transistor flyback driver in a matter of minutes and do quite a lot of nasty things with it ;)

NOT a problem

[jridley]

I've gotten whacked with charged flash caps a number of times. It's about enough power to make you jump a bit and shake your hand.
The article talks about "holding it on someone for 5 seconds" - well, that won't do a damn thing; this is a capacitor, it discharges and that's it. There's a charging circuit, but it's very wimpy; it takes the circuit 5 to 10 seconds to put that much energy into a cap for a few millisecond shock.
You want a deterrent? Learn to run fast. You're going to need it, ESPECIALLY if you try to use one of these things.

I made one a while back...

[n17ikh]

I made one a long time ago and decided to put it into an altoids tin. The red button allows it to charge, the toggle switch sends power to the "terminals". Charges to 330 volts in around 10 seconds, and drops about 30 volts every time you zap someone with it. The duct tape "battery holder" gets kinda flaky sometimes though...

www.n17ikh.com/images/stunner1.jpg

www.n17ikh.com/images/stunner2.jpg Brings "Curiously Strong" to a whole new level.

Explosive Capacitors

[foxalopex]

Actually, I'm surprised they didn't point out that some electrolytic capacitors if wired in backwards can literally explode! Appearently the insulator can suffer an instantaneous breakdown causing the stored charge to short in on itself. The resulting pulse of heat vapourises the insides and since a capacitor is a sealed metal can. Well you know. I had an electronics prof warn me about this after he accidently put himself in the hospital once. Yup airplane authorities will be pleased to know this.

Yay, more uninformed stupidness on TechTV

[Powercntrl]

After watching a video where they take apart a MuVo2 for its Hitachi Microdrive and then say the iPod mini has the same drive (correct, but the iPod's microdrive will NOT work in any digital cameras), I'm convinced TechTV's "dark tips" have become dangerously innacurate.

Don't do this. Compared to a stun gun, a photoflash capacitor stores a lower voltage, direct current high amperage charge which is delivered all at once. Yes, if delivered across the heart, it could be leathal. If delivered across flesh, it will burn you. In almost no cases will it stun you other than the surprise of getting shocked.

Real stun guns use a high frequency alternating current, VERY low amperage spark. Real stun guns are also quite cheap on eBay.

If you want to make a joke shocker from a disposable camera flash, here's a much safer method:

Get a cheap disposable camera and take it apart. Discharge the capacitor with a screwdriver. Get rid of the capacitor.

Notice the heavily insulated wire running to the center of the xenon photoflash bulb? Remove it from the photoflash bulb and attach a longer wire that will go to one of you're "shocker's" probes. Make sure the connection is well insulated.

Locate the portion of the circuit board that is shorted to activate the flash charging circuit. Usually, it's a small flexible metal "button" with plastic over it. Yank that sucker off of there and short the points on the board out with solder, or if you like, you can attach wires and add your own on/off switch.

Get a battery holder, some sort of case to put all this in, and a momentary pushbutton switch. Attach the wires from the battery holder to the circuit board, a wire from Negative to your other "shocker probe". Connect the momentary pushbutton switch to the trigger circuit (usually two peices of metal that were positioned near the shutter). Position the probes to be less than 1/8" apart. Put all this crap in a box and try it out. When you press the momentary pushbutton switch, you should get a nice spark.

Re:Way back...

[skasingularity]

Once me and some of my friends were staying in a hotel in Hilton Head, and we stopped by the local mall. We found a camera store and they gave us a box full of disposable cameras for free. We took a bunch of them apart, and in the name of science, I donated my to be shocked. We ran some copper wires from one of the flash units, and used pennies as contacts. I taped one penny to the back of my hand, and one to my palm. It wasn't working, so I pressed on the pennies, and they got close enough to run a current through my hand, making my whole arm tingle, and leaving circular burn on my palm and the back of my hand.

Yes, it did hurt.

Re:This is dangerous

[merlin_jim]

Problems here:
- NEVER touch power supply caps, they can store 10x - 20x the energy of flash caps. Lethal!
- Discharge the CAPs from the power supplies before salvaging.
- Discharge the unit after use with an *isolated* gripper, better yet, a high-wattage resistor (few kOhms) hold by an *isolated* gripper.

I deal with high voltage power caps in my hobbies of railgun and coilgun design. Whenever building a prototype, I know I'm going to be monkeying around with it, and I know I'm going to get shocked accidentally...

So I take a high ohm resistor and put it across the cap leads. Put it as close to the cap as possible; if it's after you in the circuit, the high frequency nature of the cap discharge can cause it to not affect the circuit.

How big? Well the resistor here is serving two purposes; one as a bleed resistor. In that case, you want it's rating high enough that it doesn't put a strain on your charging circuitry, but still low enough to bleed power relatively quickly. From that standpoint something between about 10 KOhm and 1 MOhm should be good; caps don't have a ton of storage capacity so even a high value resistor can bleed voltage relatively quickly. And 50V, while impressive, just isn't as dangerous as 1000V... Batteries usually have an internal resistance of about 80 Ohms (the battery appears to resist the flow of electricity like an 80 Ohm resistor would, when it is in short circuit)... depending on the efficiency and design of the charging circuit, low resistances might significantly affect its performance.

Of course the other side of the equation is that the resistor is the last line of safety in case of accidental short circuit during charging; during a short circuit, the resistor will absorb some portion of the power. My trusty voltmeter says that my resistance from terminal to terminal (that is, one hand to the other) is above 1 MOhm when lightly touching the terminals, and hovers near 47 KOhm when I am.

I'd like the bleed resistor to be significantly more conductive than I am; if it's before me in the circuit and I'm lucky enough, it might save my life... I usually choose about 10 KOhm.

Oh and I'm experimenting with putting it in series with an open-core inductor. From a power perspective, an open-core inductor is a magnetic energy storage device. And for fast spikes, an inductor ends up having far more energy storage than a capacitor. By having it parallel to the capacitor but series with a large resistance, I shouldn't affect the discharge time total as I would with an inductor in series with the cap. The inductor shouldn't affect the circuit inductance enough to matter (typical circuit inductance in a coilgun might be 100-2000 mH)

But that's all beside the point. The point is: bleed resistors don't have to be held in place. For maximum safety, make them permanent...

Of course, that's assuming that your charging circuit will provide charge constantly, and isn't on some sort of timer or level sensor...

Easier method yet....

[Tmack]

Take a transformer (no, the electrical kind, not the shape changing robot kind) thats got different primary and secondary windings, and a 9v battery. In its simplest form, take the two wires from one coil and attach to battery while victem holds the others, then disconnect the wires. For a better effect, connect/disconnect very quickly. A friend and I had a bunch of fun making shock boxes (back in Jr High) with this, to the point where we had a metal cube about 3" per side with a mercury switch inside, and all sides of the cube isolated and on different ends of the coils. As long as you held it level and didnt shake it you were ok, soon as you handed it to someone, they probably would trigger the mercury switch and get shocked, causing them to drop it. Another box was cardboard with bare copper wires run underneath cloth athletic tape on the outside coonected to the transformer. It had one button on top that had "DO NOT PUSH THIS BUTTON!" written around it...

Tm

I remember this from 1993

[pantycrickets]

Boy.. how times stay the same. :)

How to make a ZaPPeR GuN
By Panther Modern TNO/TBF

The zapper gun is kinda like a commercial stun gun. It is not as
powerful, and is mainly used to piss people off, not to put them down.
It will scorch skin very painfully, if applied. Total cost for it is
around $20-$25, and it is a fun thing to make if yer kinda bored.
If you don't know what a capaciter is, read no further, go find out
what one is/what one looks like, then come back. Anyway, materials
are:

Qty Description Approx price

01 Disposable Fugi-Film FLASH camera $15+TaX
01 Small-Mid radio shack projekt BoX $2-$3 or so..
02 Dry wall nails 10-20 cents
01 Radio Shack SPST Push Button $1.50
01 1 Alkeline AA battery $0.50

This is to make a fairly nice version.
For the raw, crappy version, all you
need is the camera. I won't even go
into details on making it, you can
figure it out for yerself.

Okay. Get the camera. If you want, take some pictures. ALL OF THEM,
or none of them. Cause if you don't take all, you'll ruin the film..
Now, when yer ready, first, rip off the cardboard. You'll have a plastic
box. Open it up, as well as you can. Be very careful not to damage the
circuit board, wires, flash, etc. Once it's open, discard the plastic
case, and the film. Now, looking at the circuit board, one can see
a fairly empty space. Rite in the middle of it, will be 2 small copper
"plates." Soldier your button to this place. YOu may also remove the
flash at this time, as it will be shortly rendered useless. Also, you will
notice two protrusions of copper strip. Pull 'em off, and MAKE SURE they
aren't touching when you finish, cause it will ruin the gun. Next, put
the circuit board in the project box. Drill one hole so you can see the
LED. THis will tell you when the gun is ready to FIRE! (When the LED
flashes). Next, line up approx where you want your two tips. Line up
the capaciter with this. Drill holes. Next, drill one last hole where
you want the button. Now, remove the generic AA battery in the camera,
replace it with your hi-quality Alkeline AA battery. Now, stick the nails
in, and soldier them via wires to the two capaciter leads. Seal them in
place with either expoxy or hot glue. Now, wire up your button, and stik
the LED in the hole you made for it. CLose up the box. Your gun is made..
Just push the button, holding down for apporx 2 seconds until the lite
flashs, and touch whatever you want to SHOCK. This gun is semi-lame, but
is also fun, and good for boredom..Have PhUn!!

Re:Don't think this is going to work to well...

[Lifewish]

I'm not sure that the effect of touching a finger to a wire is representative. The effect will only be produced by the positive-earth potential rather than the positive-negative potential, and would be a lot less than you'd expect.

For example, when I was a kid I decided to dissect a light switch - with the mains power on! It was only after two minor shocks that I remembered to put rubber gloves on. If touching a wire could have the same effect as the main blast of the current, I wouldn't be here today :(