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Need help choosing a transformer

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OverTech

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Years ago there was a guy that made these tingle toys. They operate off a 9V battery and deliver anywhere from a mild tingle to a pretty good shock, depending on the "Intensity" knob. The frequency of the DC pulse is also adjustable depending on the "Speed" knob. This guy is no longer around, but I want to make a couple more of these toys.

I have the whole thing drawn out and I've identified all the components except for the transformer. It's an ecapsulated PCB mounted transformer with no markings at all. All I know about it is the DC resistance values for the primary and secondary. The primary is 18.4 ohms with a center tap, the secondary is 3.2k ohms.

Here's a quick sketch of the circuit:



The square wave is generated by a standard 555 circuit, then fed into a hex inverter chip, then to the transistors. It is low voltage and only serves to switch the transistors. The 9V supply comes in on the center tap. I really have no way to accurately measure the output voltage or amperage without a scope. With a multimeter on the DC setting it reads about 1.5V @ -76mA, but I don't think that means much in this case.

The transformer itself looks like this:




Could this be just a standard 12.6VAC transformer wired up "backwards"?? Any suggestions on where I can order one for PCB mount (part numbers, URLs)??

Dave
 

lavenatti

Member
A 120:12.6VAC transformer wired backwards would work ok. You could even try an impedance matching(audio) transformer. They are usually in every junk radio you find. I always test these things on my friends.
 

OverTech

New Member
lavenatti said:
I always test these things on my friends.
That's a nice way to do it! :D

I picked up a Radio Shack 12.6VAC transformer today. Think I'll just wire it up in place of the original and see what happens.

In looking through old posts here, I found this to be a common topic. Everyone is looking for 200k to 1k transformers mentioned in an article about building a stun gun, but nobody can seem to find them anymore. So, I'm glad I'm not the only one searching anyway... ;)

Dave
 

OverTech

New Member
The Radio Shack 12.6V transformer does deliver a tingle, but it's weak. Very weak when compared to the original transformer. Back to searching for a powerful, high ratio, PCB mounted unit... :(

Dave
 

stevez

Active Member
Seems to me that I purchased a Radio Shack 8 ohm to 1000 ohm audio transformer not so long ago. The turns ratio would be about 10 times greater than the 12 transformer. Current handling is extremely limited. As suggested - transformers like that can be found in older transistor radios - also tube type.
 

lavenatti

Member
Remember you are only multiplying the voltage about 10 times with the 12.6V transformer. A 120VAC:6VAC would double that.
 
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