How to specify, find a transformer, given circuit schematic?

[Charlweed]

I'm an electronics neophyte, looking for a transformer, to generate a spot of plasma at the end of two leads. In particular, I am trying to build the circuit here:


This circuit is published in a couple of magazines. The last component I need to finish the circuit is the transformer that converts 12vDC to “a few kv” at kilohertz frequencies. The author calls the transformer a Tesla Inductor, and suggests obtaining one by pulling one out of a furnace ignition system. I have had no luck finding a used furnace ignition system that has a transformer.

I would buy one new, but neither the schematic nor the articles detail the specifications of the transformer, and I do not know enough to infer them.
I have figured out that I need a low current, high voltage transformer. This may be known as an ignition, or spark, transformer. I think I need to know at least the impedance and operating frequency, as I have inferred the input voltage (12) and input current (10 ma) from the 555 timer. I do not know if I need the winding ratio, wind count, resistance, or anything else.

Thanks for any help!

[I_Daniel]

If you could get a standard automobile ignition coil, the oil filled type, then with 12 Volt you could get about 20Kv to 40Kv
output. Another possibility is one of those xenon tube (Strobe flasher)transformers, even an audio output transformer of 1K Ohm to 3 to 8 Ohm secondary - used in reverse will give you a couple of thousand volts.

You could also look at the winding of transformer for tasers/phasers.

If You Google "Tesla Coils" you will probably find one that tells you how to wind the Tesla Coil.