This is really boring part. But we have simplified this process also. We will use sectional
topology instead of traditional layered. It requires no special materials and skills to make. For this, you will need 20mm PVC pipe
like those used in "spud gun" but much more thinner. Just go to your local hardware store and ask... You need only 2" piece.
Then you should make sectional bobin from this. You can use special lathe machine or the following method. Take a drill and find any straight bolt that fits in. Fix the tube over it using insulation tape or something. Now you need a cutter tool, which can be made from a piece of steel plate approx. 2mm thick. Or something else, just use your imagination. Turn on the drill and begin to form sections. Your goal is 2x2 sections, e.g. 2mm high and 2 mm wide. After you finished with sections, take a knife or hacksaw and make longitudinal cut
, 2-3mm wide, across all sections to let the wire run free from one to another. Then i suggest you to drink some beer ;-)
...Because here starts the most interesting. Take #32 AWG enameled wire, and wrap aroud all sections, from one to another. You can use drill, but don't let the wire overfill
the secions, it's very important. Make an output lead at the beginning of wire. But don't do anything with the end yet.
Now you need to find ferrite rod of about 10mm diameter. This should be the same #77 material or better one, NOT just any rod from AM receiver! I don't know if it can be found in america or elsewhere, but in Russia this type of core in unavailable. So we invented some ways to get it. The first way is the use of salvaged TV FLYBACK TRAnSFORMER. In can be broken apart, then machinered to form a rod. This process is well shown on the pictures. Note how to break ferrite correctly.
Another way to make a rod is to use many ferrite rings glued together. it's an apropriate way, but not actually recommended.
Cover the rod with a layer of insulation and wrap 20-25 turns of #20 AWG wire, be sure to center the winding... ATTENTION!
you should wrap in THE SAME direction as in secions, otherwise it will not work. Cover it with additional few layers of insulation, to have tight fit into bobin.
Then insert the rod into bobin, and CONNECT WINDINGS TOGETHER
at one side. Ypu should get 3 output terminals instead of regular 4: input, ouput, and common leads.
In the final stage transformer is placed into cardboard box and then filled with melted paraffin. You should glue leads with the box to prevent wax leakage. Then transformer is placed under hot air stream, in example household heater on fan. This will cause all fuckin' air bubbles to come out and go fuck ;-) The box should be made with height reserves, because wax will collapse when cooling. This process concedes nothing to factory vacuum technology on quality of electroisolation, but it can be performed at your kitchen without problems ;-) The only thing that matters is paraffin quality. Look for a dark-brown colored candles because they're much stronger.
If you're done with the transformers you can continue reading further...
It's time to see it. As i said before, the circuit is very simple. It's based on self-oscillating Royer-type converter. By the way, it's not very critical what circuit to use. This can be anything rated to deliver 10-15 watt output. What i like in this design - it's very flexible; you can get power range from 10 to 50 watt only by playing with power source, nothing else. Of course it's not very practical for other applications, because of bad thermal mode, hard to control frequency etc. But we're making a stun gun, which works in pulse mode, and this is not a problem at all.
Converter charges two capacitors which are separated with diode to prevent forming one ciruit. This is done to simplify overall design; in the other case we need standalone transformer winding and second FW bridge. More parts, more complications... So i think one diode is much better for practical usage ;-) This leads to only one limitation: the capacitors must be of the same type and value. I think this isn't very critical too ;-)
The thing labeled "1400v" is a surge arrester. This is a gas filled spark gap, small cylinder shape thing with two leads. It's manufactured by several companies like EPCOS, CITEL, BOURNS and others. I suggest to buy exact type as specified in parts list
. Operation of entire device depends mainly on surge arrester and capacitors, so choose carefully, "just any cap" will not work or even blow instead! All other parts can be of any type. You can use wide range of MOSFET's from IRFZ24 to IRL2505 or just any other that will handle required power level. 3300 cap limits the initial current pulse at the start of charging. It's not required and can be safely excluded from the circuit, if you have enough powerful transistors, like IRFZ44 and better.
You may have noticed, that here's one interesting issue with ciruit operation. If you short the output, the second capacitor will not be in time to charge; the frequency of pulse repetition will rise and device becomes a "shit rattle" :-( This can happen in case of direct contact of both terminals with opponent skin. However, this is not critical because capacitor voltage is only 1000 volts, what is insufflicent to break even a thin vest. But if you are definately going to start a war with nudists :-D YOU SHOULD USE A SECOND ARRESTER
of the same value in series with any of output terminals!
Few words about actual construction. Entire circuit fits on 40*45mm PCB. The power source is six sub-AA 300mA/h NiCd batteries. They are sold in blocks of 3 or 4 as replacement for old cordless phones. These are low cost ones. They give about 15 watts of output power. You can either buy professional batteries used in hobby aircraft modelling. They have much higher capacity and current output. With this sub-type batteries entire device can be fit into a size if cigarette box. Of course other types are allowed; you can use AA, C, D or even place car battery inside a backpack and wear it :D But do you need a weapon or a toy to play?
Now take a heatsink and install transistors on it. You should isolate them from the surface, or either use two separate heatsinks. The initial assembly is recommended without pcb for testing and debugging purposes :-) Output leads should be placed close, say 1/2" for beginning.
Now turn in on. IMPORTANT! While testing, use exactly the same power source you plain to use in final construction! It should start working immediately. With 6 NiCd's repetition rate will be about 35 per second. If it's much less you should check out the transformer, or pick up the correct value of "330" resistors to match your MOSFET's. Look into the datasheet and find "INPUT CAPACITANCE" value. The more it is, the less resistor value should be, and vice versa. In example, for IRFZ44 it can be up to 1k, and for IRL2505 it should be lower than 240 Ohms.
When the output in tuned, you can increase the distance between terminals, but consider that final distance must be at least 1/3" less than maximum available from the transformer. Actual spark distance vs voltage depends on many factors like air humidity, pressure etc. So you need some reserve for safe operation.
Now, if everything works well proceed to the next section...
Making the case
Here it is, another fucking hard thing :-) Since we have no ability to make real plastic cases the only thing we can use is EPOXY RESIN. Hard process as i said, but it has advantages also. You will get a monolith, shockproof, water-resistant case, and perfectly isolated. In addition it can be used istead of knuckleduster :D For this process you will need epoxy, glue gun, cardboard and some other stuff. The proccess is well illustrated so minimum descriptrions is required.
Start form making "top" view profile of your stun gun. It's very convinient to use squared paper for this. If you have no idea what the shape should be, just google for some stun gun pictures or look at the first page of this article.
Cut some stripes about 3cm wide from the same cardboard. The actual width depends on the maximum height of stun gun parts. It's better to make a little more than a little less....
Now you should glue over your base with these stripes. This requires some patience, you need to wait every time to let the glue cool down. Glue from the outer side, and watch for joint impermeability.
The first fitting : place all parts inside the case and watch if they are fit correctly. At this step you should decide where the swicth, button, and charging port will be.
Final assembly. Connect all parts and test if it works. Use shrinkable tube to fix elements, and make them "wreck" into the case. This is useful because after epox will consolidate you need to cut off the cardboard and some epox too, what results into 2-3mm loss on sides. Use threaded rivets as electrodes. They consist of aluminium facing and a central STEEL rod, so you should expect no difficulties with soldering.
Pour the epox! But consider that is has very bad ability to permeate everywhere you don't need it ;-) So check all the joints for impermeability. Did it? Do again. Now you are ready...
Over 6 to 8 hours epox will consolidate, but it will be still very soft. At this moment you can use carver or paper knife to remove the cardboard and shape the thing to fit your hand and nice look :-) Final processing is done with sand paper or something like. After all you can cover it with some paint.
Complete form. Looks like commercial stun gun, isnt it? You can congrat yourself and...
...Proceed to the final part.
So you made it. It produces loud bright sparks, and impresses you friends ;-) But how exactly we should test it? At the beginning, we said that it's the current that matters. So let's find it. Compare the pictures below, regular stun gun on the left and our malicious thing on the right ;-)
You can see that spark is much thickly, it has yellow color and flashes at the ends. This means very high current. How exactly high? do a simple test. Take 0.25 Amp fuse and place it between terminals, not touching them. The fuse will blow. This means curent is higher than 250 miliamps!!! Compare it with couple miliamps in regular stun gun :-) Clearly, that actual value will be less because of body resistance, but still TENS TIMES more than in regular stun gun! We can only guess what malicious effect id produce ;-)
Few words about advertising trick with paper firing, used by some companies to make impression on inhabitant people.. In this trick, firing occurs due to high frequency (100 and more) - even a rattle from the left picture can handle this. At the frequency of 35 hz, as in our device, any commercial stu gun will not leave even a trace! Our malicious device fires paper instantly. It can even burn a matchbox or something like. Small video about this process can be found >>> here <<<Links
1. http://www3.telus.net/chemelec/Projects/Stun-Gun-3/Stun-Gun-3.htm - Gary's stun gun project. Basic theory explained. Recommended especially for beginners with "stun guns"
2. http://stungun.h16.ru - a project about commercial stun guns : see what you pay money for.
3. US 2004/0156163 A1 - US patent on AIR TASER
That's all for today. Of course many things, like another version of circuit, application anatomy and combat testing, have remained behind this article, because they require much time to be completed... So it will be updated when results come. As for now, you can post our FORUM
- for questions, comments etc..