posted February 24, 2000 06:41 PM         

Research still continues... Good news:

Good news, I got the 555 circuit running a long time ago, it was a 100k resistor mixed up with the 100ohm resistors in my box. I still am going to tweak the circuit to lower the frequency so that I can get a longer spark and higher voltage. More on that when it is done.

PVC pipe jumps from 2" to 3" sizes, so no 2.5" pipe to house the car coils in. I say coils because I use 2, that gets me a nice long spark. I am now using 12v 6 & 7 amp fire alarm system rechargeble batteries to test the system to save 9volts. 1 9v should last a long time unless you run the stun gun for minutes on end, which means you probably aren't shocking the person that bad. Rechargeble 9v are another option if you like to stare at the sparks for long periods of time Back to the size, 3" PVC pipe will have to be used to house this current system, or you can use much, much, much, smaller PVC pipe with the info in the next paragraph. I am thinking about using the 2 coils I have and making a jacobs ladder and using the next method for the stun gun.

Want smaller coils? They are avalible. I don't have the exact dimensions but they are much smaller in diameter and about 1 foot long but I belive that can be shortened. New standard car ignition coils cost about $20 USD, but can be obtained free or for a few dollars at a salvage yard (when my project is built I will have info on obtaining parts like this along with all my experinces). Cars made I think about 10 years ago like V-6 computer controlled firing have a coil for each spark plug instead of 1 main coil. These are smaller since they aren't being fired as often like the large oil filled ones do. So if you know someone who totaled their car and it has these, nab them, a v-6 will have 6 coils, enough to make 3 stun guns with. Removal is even more easy, just unclip the wires, unscrew the coil and pull it out. They are mounted in the engine and the spark plugs are underneath the coils.

I have not priced them at a salvage yard yet, I am waiting to see if my friend's brother's car is a v-6 with these or not first. I will find out eventually anyway for my report(webpage) on this. I could also drive back to this town to look through the old abbandoned cars to see if anyone of them has them.

posted February 28, 2000 11:59 PM         

I'm working on making this a baton sized stun gun, so far so good. Tommorow I will be getting the small ignition coils and changing the circuit to fire at 20hz. I found this out on a patent on the web. They claimed this is the frequency which excerts the muscles the most. I did have it at 300hz, so this should give me some higher voltage also. The page I calculated was from http://www.74.co.uk/lizard/555/hiframes.html
My deciscion of using a 555 circuit was good since you can precicly tune the frequency and it saves on parts and wiring many things.

Ok, now for the questions, my setup is 2 ignition coils wired with thier primaries in parrallel & secondaries in series. To get more voltage I can try 2 things.

1) Increase the voltage going in. I would do this with a small transformer before feeding this output to the 2 coils. How many volts can I get away with before the insulation breaks down in the coils? I'm thinking I might be able to get away with 24v maybe 30v.

2) Increase the voltage after the coils. Can I do this with a self-built voltage multiplier cascade using 6kv caps & diodes? Or will the voltage be already too high(30-60kV) and destroy them? What if I used a multiplier out of a TV?

I'm thinking #2 would be the best if it works. #1 would be even more but will put more load on the batery you are using. I will also test out using a diffrent transistor to pull less current and reduce the heat...

Current is what gives a jolt from stun guns.
The current in the 800 volt supply is about 20 to 30 times greater than that from the HV leads. The HV is only needed to cause a spark to jump through about 1/2 inch clothing, max.
Anything thicker and the electrodes on the gun will usually arc over.

Point is dispense with the entire HV transformer, and use the 800 V with pin electrodes that punch through clothing and into meat. This will make a jolt that will floor any animal, except maybe an elephant, which would then trample you as it departed blindly at max speed.

A post that mentioned using straightened fish hooks as electrodes was good. The ones I tried to straighten though had to be heated red hot to bend, and no matter what I did about cooling them they ended up very brittle. they do make a good plug in and stick weapon though.

The step up circuits for the battery to 800 v
part of commercial guns is much simpler than the Hv ferrite transformer to duplicate.

Electric fence chargers for cattle etc, usually limit the current to a max of 30 Milliamps. If you've touched one with meat touching it and ground you will know what that small current can do to your resolve.

Also, an electrolytic cap of about 100 mfd, charged to 150 volts dc, and applied to the head at each temple, with salt water wetted pads, will equal electroshock therapy the shrinks use. It causes instant unconciousness and grand mal seizures which can sprain muscles, and sometimes break bones as the muscles turn hard on. It also causes the short term memory to be erased before it can be stored in long term memory. This memory holds about the last 5 minutes of your recorded memories. The result of this erasure is the patient awakens with zero recollection of what happened, where he is, who did it, etc, and confusion reigns for a couple hours after conciousness returns, which usually takes about half hour or so. Talk to someone who has knowlege of electroshock therapy, such as a patient or nurse etc for details on recovery times and side effects.

A covert agent had a pocket device like this with electrodes built into his right hand glove thumb and first finger, which he could put on a persons head, and the glove was insulated except for a leather spot over the electrodes soaked with salt in antifreeze sol. (so it wouldn't ever dry out).
He claimed he could usually get it planted on a head by saying to the guy Hey, you got a spider on your head, let me brush it off.

The power step up to make this system is simple in the extreme. The usual camera flash unit that runs on one AA cell has all the works in it for this. Its cap charges to about 150 volts, and has the storage capacity to do the job. You can even leave the flash tube in the circuit to the head electrodes, and then fire it using the camera shutter firing mechanism after you have a tight press on the head. This is no good anywhere except on the head though.

These cameras are available everywhere for many throw away cameras have flash. A new one costs only a few bucks.

posted March 11, 2000 07:41 PM         

From some quick tests using my new smaller coils which seem to put less stress on the poor ole 9v's a 3/4" spark gap creates a purple/orange arc using about 22 or smaller guage wire (very small). That is at 300hz with 2 coils combined. I will be lowering the frequency to 20hz soon. 1hz I know makes higher voltage than 300hz since I switched manualy as a test once and got a longer spark

I re-read through some of the patents last night and have thought about doing some changes.

• Original design: 2 small ignition coils hooked up so they fire together (not through one then the other) running @ 20hz. 3/4" spark gap and 2" spaced prongs both running off of the same HV output leads of the coils.
  
• New design: small xmfmr -> spark gap & cap design discharges into 1 coil which then goes to prongs.
  

A voltage multiplier is too hard to obtain/make/keep small in size so I left it out on my plans. This unit will be small and have a baton style shape.

posted March 30, 2000 11:46 AM         

Going to re-tune the circuit so that the motorcycle ign. coil works best, then fires over a spark gap and then into a self-wound 1:5 HV transformer.

Another design I haven't tested uses a photoflash xfmr with capicitor cascade/spark gap and another self-wound small step up xfmr. This circuit could be modified further by replacing the photoflash xfmr with this ionizer one: http://www.allelectronics.com/online-store/scstore/p-SW-750.html

Soon I'm going to make a 3D&2D CAD drawings of the whole thing for the page I will be making.

I'm wondering, how many people are still interested in this?

posted April 02, 2000 03:53 PM         

So you're going to have to steal or get free somehow these things from a friends wrecked car, a newer ditched car, or elsewhere.

The coils from the motorcycle are about 2" high by 1.25" wide by about 2.5" long. Not bad I think I can work them into a 2" PVC pipe. Car coil packs are odd shapes though small. There may be 3 of one shape and 3 of another shape in one car alone.

If anyone goes to get a smaller coil and gets one cheap let me know how your adventure went. Keep in mind I'm keeping this below cost of buying a stun gun (~$20 bucks), so if your buying coils for more than this it's not worth it.

*Also the smaller coil tends to eat up less current in the battery and output more current at the electrodes producing more of an arc. I belive it is because there is more resistance in the smaller coil due to smaller sized wire, so it doesn't "short" the 9v as much. In other words they work better

Coils are available at Autozone in USA, and auto parts stores elsewhere for about $15 in usa. These are generic round coils about 2 inches diameter, 5 inches long, with two LV input screws, and one tower for HV output.

They have about a hundred to one turns ratio, and like to work on 12 v with about a 1 ohm resistor in the line to avoid melting the coil if you leave the points closed for a long time.

photoflash xfmrs are best gotten out of the cheap cameras. Take the whole circuit, and measure its DC across the strobe tube when its light says its ready for flashing.

For parts search electronic surplus on the net. In usa Goldmine is good, but many come up with any search engine. Goldmine has no minimum order I think.

Also radio shack has parts.

Try hamfests, which are electronic flea markets for ham radio operators. They have these worldwide. Check with any electronics store or ham for dates and places. Usually parts are there in quantity.

As to other stuff here's what I wrote a couple days ago, but could not post because of time limit online. It will format weirdly because it comes from a word processor.

Some answers to questions made in earlier posts:

1. The 80 kv pwr supply contains a 60 hz transformer, diode
rectifiers, and two capacitors each rated at about 60 kv and
with about .005 microfarads each. The output is center
tapped with the center tap tied to the case so nothing sees
more than about 40 kv to ground when loaded to 5 milliamps.

Open circuit voltage will run to about 100 kv.

The blast is from the arc that is probably several kiloamps
for a few microseconds as those caps arc ball to ball
through some 5 inches of air.

2. There is a rule among electronic tinkerers and engineers
that one ought never built for himself anything that is
being manufactured. The reason for this is that for almost
all practical items the engineering design, and
manufacturing design, and special parts location and
procurement are prohibitive to come anywhere close to the
quality of a commercial product by the onesey twosey
builder.

Most parts houses for example have 100 dollar minimum orders
for a lot of the parts you will need. Special parts like
ferrite transformers etc may require a $10,000 minimum order
before the maker will design and build the things for you.

That aside, in stun guns there is a ferrite transformer to
step 9 volts up to about 800, and that requires some very
sophisticated design to make, plus one has to know a lot
about the exact ferrite core used. Design time with Computer
aided design (CAD) at a mfg. runs a day maybe.
Without CAD it can run a tinkerer a month of fiddling and
farting.

There is another one much more difficult in the step up from
800 to about 30 kv. Takes a little more time than above.

Then there are the transistor drivers for the first power
supply, which has to match the impedance of a 9 v nicad or
alkaline battery. Ordinary 9 v transistor batteries can't
hack the current this takes. Get the impedance wrong and the
battery will not put out all it could.

Then there are the requirements for very small size for 30
kv stuff, that will last more than a couple minutes before
it arcs over and self destructs.

The electrodes on stun guns are almost never a full inch
apart. For flat faced electrodes, # 14 gage diameter, it
takes about 20 kv to jump a 1 inch gap. No matter how many
hundreds of KV ads say they create, they will not do more
than about 20 to 30 kv before the safety gap arcs over.

100 Kv on small electrodes will jump almost a foot.

154 kv on 4 inch round wires of 154 kv transmission lines,
which reach about 200 kv on the peak of the ac cycle, will
jump about 3 ft which is why they use about 10 ft insulators
at the towers, and space the wires about 15 ft apart, so
when wind swings them they never come within about 5 ft of
each other, or else big bang, and no lights.

If you want to play with HV, as a hobby fine, but to try to
compete with a commercial stun gun, which I've bought in
quantity for $14 each from most any electronics store that
sells hi fi, cb radios etc, is going to frustrate hell out
of you.

To just play with HV, use an auto ignition coil, and make or
buy a standard CDI ignition unit to drive it. These charge a
capacitor of about 1 microfarad (ufd) and 400 v rating to
about 200 v dc and then dump it via an scr (or a hexfet)
into the coil lo voltage side. The coil had a ratio of about
100 to 1, so the output is about 200x 100 or 20 kv. Some
CDI's charge to 400 v and put out 40 kv, but 40 kv requires
the fat ignition wire (8mm) of modern cars to last very
long.

To drive the CDI unit at its input which goes to the points
of the distributor, make any square wave osc out of cheap
digital IC's that runs at a freq. of about 300 hz. Drive a
transistor with this to short out the input to the CDI 300
times a second. You will get a HV spark that will come out
of the ignition coil hole and down the insulating tower to
the can, and make a loud 300 cycle roar.

Or get an old color TV set and play with its 25 kv dc HV
that went to the pix tube. Careful with both of these for
they smart fiercely if they bite you. They can make you pee.

you can use the modern car's ignition coils too, but they
are kind of integrated into coil plus distributor head. They
are usually driven by a CDI unit in the car somewhere.

If you can find an ancient ford spark coil, it had the
buzzer on it to spark the input, and it made the HV all in
one unit.

otherwise the cylindrical coils you can buy at autozone, etc
are good. Get the oil filled ones for about $15. Shake them
and hear the oil slosh around. They stand open circuit use
longer than do the wax filled ones that won't slosh. None of
them like to be run with 2 inch sparks coming out the holes
for very long, for they were never meant to do that, and
will short out sooner or later.

There are electronic circuit books in libraries, which will
have CDI units, and square wave oscillators, etc.

So hope that helps. Don't mean to discourage
experimentation, but if you intend to make a unit that
competes with manufactured stuff, you need to know up front
what a task you are taking on. Your first working unit may
cost you a hundred times what you could buy a pretty
reliable commercial unit for.

transformer ratio of audio transformers is:
square root of (impedance in/impedance out)

Example turns ratio of 2 causes a impedance ratio of 4

a speaker xformer for transistors like in small radios with only half watt audio will have a z ratio of 8 ohms to about 40 ohms or a 5 z ratio and a tad over 2 turns ratio.

6 v transformer like in little plug in power supplies have a 120/6 turns ratio, same as the ratio of input/ output voltage rating. However the 120 volt winding will not stand more than about 200 volts before it shorts out due to arcing inside.

The 3 volt units to charge nicad tools has about a 30 ratio, but same limits on hv.

the turns ratio transforms voltage and current in opposite ratios.

Example a 120 to 12 v transformer transforms voltage by a ratio of 10.
So if it will put out 10 amps at 12 v it will take 1 amp at 120 v to drive that output.

Notice that the product of input = output in voltamps
example 120 v X 1 amp = 120 VA
and 12 v X 10 amps = 120 va

transformers are about 90% or better efficient, so they transfer a lot of power with not much heating up.

The amount of voltage a transformer of given turns on its winding can take is directly related to the frequency.

So a transformer that will handle say 6 volts to 120 volts at 60 hz, will handle 12 to 240 at 120 hz, and 24 to 480 at 240 hz.

So transformers that work on higher hz freqs can be much smaller than lower freq ones.

A transformer to work on say 10 hz would be big as a barrel, and no body works down low with transformers.

The amount of power a transformer can transform is related to the pounds of iron or ferite in its core, and to the frequency. This is because a given size core can only store so much energy in its magnetic field at one time. To get more energy across it you have to charge and discharge the field fast.

transformers charge and discharge at 120 times a second for 60 hz power, and 100 for 50 hz power. twice each hz because each hz has a positive and a negative cycle.

A complicated formula tells you how much core you gotta have for a given power. It depends on the material of the core. Ferrite will not work at all on lower freqs like below about 1000hz, and they like 20khz to 100khz.

Transformers are hard to design, but if you find one that is big enough to put out the VA you need, its not too hard to change the low voltage winding to give you what you want. Its a bitch to change the hv winding (like the 120 v one) though.

So if you find one that will put out say 12 v at 2 amps, and you want 6 volts, first try to find one that has a center tapped output for it gives 6 v from either side winding to center tap. If not, take it apart, and unwind the 12 volt coil, counting the turns you take off, and put back half as many. Easiest way to do that is fold the wire you took off to double it and wind it all back on. It may not fit if you don't neatly do that, but it will then put out 6 v at twice the current it put out at 12 v.

posted May 01, 2000 08:50 PM         

I am writting a .doc for now that contains info needed to know when designing a high voltage device like mine, and the several designs for the circuitry. I will expand upon it when I convert it to html for the site. My first design will be using one of the small motorcycle ignition coils fitted into a compact PVC baton. After I have this one firing up to par I will then work on much smaller transformer designed systems.

I have recently gained more knowledge that will help me in my work. Only thing left now is start experimenting heavily to see what works best for the buck/size/avalibility.

Hopefully in about a week or two I will have the first model made(motorcycle coil one) and be ready to work on the other designs. 1 9v can be realy painfull in the right hands

*** Added question: ***
acdc said that car ignition coils have a 1:100 ratio... I don't think that is so since 9v will cause a 3/4" spark and that doesn't seem like only 900v... Allthough I did notice that the unit that drives the motor cycle ignition coils has some SCR's and 1 400v film capacitor inside it. So if I drive the coil with 200v pulsed from this cap it should be able to handle it?

Also, Radio Shack has some HV ceramic caps, some as cheap as 49 cents, not sure of how many you get though. 6KV peak 1-5secs. Perhaps a voltage multiplier will be designed for my next stun gun model... http://www.radioshack.com/ProductCatalog/ProductListing/Index/1,2094,CTLG_010_002_005_000,00.html

posted May 06, 2000 12:17 PM            

It probably depends on the coil as to what ratio it is.

posted May 07, 2000 12:22 PM         

The 3/4" spark is from 1 single motorcycle ignition coil. Today I will be building a CDI unit and feeding the coil 100-200 volts, so I will get mad voltage after that. I will use the SCR & cap that came out of the same unit that was made for these coils on the cycle. The motorcycle coil works much better, and probably can handle much higher frequencies. When 2 are hooked up I get almost a 1/2" orange arc. Fried a horsefly realy good with that and set toliet paper on fire in an instant just from 1 9v battery!

As for the circuit, I am running a 555 timer with a .1 uFarad ceramic cap, and 2 11k potienometers for resistor spots 1 & 2. Actualy it is 2 10k potien's with a 1k resistor in series. This then drives a 2N3055 power transistor to amplify the signal. This thing doesn't get hot at all, and small normal trans could be used if this was not held on for long periods of time. So if this were used as infrequent as a stun gun they probably could take the heat easily. Frequency on this works out to be about 300-400hz. I have not tried higher, but lower gives you less performance. I will try to measure the frquency with a meter sometime, but in the mean time, check out this URL.
http://www.74.co.uk/lizard/555/hiframes.html

posted May 07, 2000 08:24 PM         

Also, could someone provide me with an inverter design using 2 trans & no caps? One that will work for a transformer that doesn't have a center tap? I need a small generic one for T1 in my experiments.