Make a 9V powered zapper?

My friend has this thing that looks like a pack of gum and when you grab and pull the piece sticking out it shocks you, it isn't really that powerful, but I want to make a better one.  I opened it up and it is a fairly simple device.  It has three button cell batteries with the negative side attached to a contact plate and the positive attached to the capacitor.  The capacitor has the neg attached to the same plate as the batteries negative.  The only problem is that the positive plate is attached to a third prong on the capacitor.  Why would a capacitor have three?  I have tried charging a 220 uf cap. with a 9v battery, but it doesn't deliver any shock even though it should be higher voltage and capacitance than the original device. 

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iceng5 years ago
Try some tiny $3 transformers from mouser with a good turns ratio
or you could wind one yourself on a 10 penny iron nail.

6fig14.gif (author)  iceng5 years ago
Oooh, I think I might just use a camera though, is it essentially the same as this, but with a capacitor?
iceng jj.inc5 years ago
Reduce the voltage as I know you can....., and put a series resistor to limit
current below a milliamp then put a tiny cap on the output to give it the
sudden sting....

We don't want to Harm anyone... (author)  iceng5 years ago
Yea, but why would the voltage need to be reduced? Aren't disposable cameras around 300v, which is the same as the thing you sent me, I would of course use resistors.
iceng jj.inc5 years ago
I would have given the same cautions along the way.

Do you really want to personally get a 300 V flash energy across
your chest from hand to hand ? :¬þ (author)  iceng5 years ago
ok, about the reducing voltage, I actually don't know how with the 300v. I could do it with 12 or so, but that is left from other projects I have seen.
iceng jj.inc5 years ago
The circuit stops drawing power when it reaches the flash discharge
voltage.  You can ;
  • search for the control divider and reduce the the high resistor for a lower target voltage.
  • replace the main cap  with a much smaller value one
  • a small cap that makes for a faster re-charge
  • place a resistor across the cap to force it down
  • in all cases place a series resistor in the shock path
  • make the resistor limit current under 1 milli-amp
  • Add a tiny cap on the output for the sting !
I made these when I was a kid with a 9v battery and a transformer.
All you have to do is connect the 9v to one side and extend the leads of the other for output. All the other components aren't needed, but you could put a button on it since you only get one zap each time you connect the 9v. I don't know which coil to use, but just switch them around until you get zapped or use the picture from iceng with all the other components removed :D
niftynev5 years ago
If you measure the resistance of the little inductor/coil, it should be very low - probably less than 5 ohms, if not close to being a short circuit. My bet is its a coil. Having 3 leads, Iceng is probably close to the mark as to its wiring, & it being an autotransformer. Mpilchfamily is probably correct re the little board with the epoxy 'blob' on it too.
There's more to it than you've found so far. You can't boost voltage without some switching, or inductance.

I'm guessing there's an induction coil hidden in the gum packet.

Steve (author)  steveastrouk5 years ago
Maybe that is a coil instead of a capacitor, but I don't think so because it takes time to charge, here is a pic of it.
That looks like a mini-inductor to me. Measure its resistance.
+1 That is a small inductor but what is that round bit at the bottom of it tied to 2 of its leads? (author)  mpilchfamily5 years ago
It is just a board they used to make the connections I think, but it does have a big black blob on it.
That black dot is generally an IC of some kind. There are probably a set of transistors under that blob that help amplify the voltage in conjunction with the inductor. (author)  mpilchfamily5 years ago
ok, thanks, well I guess it will be a little more complicated than I expected, darn. A disposable camera flash isn't dangerous is it?
If not handled correctly it can stop your heart. Just don't touch the lead with either hand allowing the circuit to short through your hear. Back in high School my friends and i in Electronic class would make tazers from the flash circuits. We added a power switch to charge the circuit then a trigger switch and a couple of thick copper leads and placed them inside a small project box. Leaving the copper prongs about 1 inch apart. Then we would zap each other and leave little burn marks where the tazer discharged.

Keep in mind the camera flash is storing several hundred volts in its capacitor. It can be dangerous. (author)  mpilchfamily5 years ago
Oh wow. Iceng recommended some resistors. I have a bunch out of an old CRT monitor and they are pretty big so I think I will use them along with either no capacitor or a tiny one to replace the original. Thanks for the heads up, and yea, any current through the heart is dangerous, so I will need to be sure to make sure it isn't in the path. (author)  steveastrouk5 years ago
why would it need time to charge though, and can it be boosted?
Dunno. Like I said, measure the resistance.
rickharris5 years ago
Searching is a wonderful skill

Look right >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> (author)  rickharris5 years ago
All of the ones I have seen require a transformer, and most are for a fun little buz, they are tazers and the such. None of them consist of a just a battery and capacitor. I don't ask questions without doing a little lookup first.
iceng jj.inc5 years ago
The three lead thingy you call a cap is an auto transformer like a jewel thief
on steroids.

Steve asked about resistance as do I.