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Re: Another capacitive transformer TC



Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:
> 
> Original poster: "Jolyon Vater Cox by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
> 
> Would Terry Fritz' Tesla Coil Tuner
> http://hot-streamer-dot-com/TeslaCoils/Misc/TCT/TCT.htm
> -possibly modified to include an emitter-follower output stage- be
> sufficient to perform the ping test.
> 
> This is an equal mark/space astable giving almost symmetrical square wave.

It would work, but with a larger timing capacitor, and with the
output directly connected to the gap. I prefer the connection that
uses two resistors and leaves pin 3 just for output.
 
> Would TIP 31 npn and TIP32 pnp power transistors be suitable for the emitter
> follower?

A complementary follower would not work correctly as a buffer with a 
direct connection to a 555 (the output would change +/- 1.2 V at each
current reversal). What I am using is a simple emitter follower 
with a BC337 NPN transistor and a 100 Ohms resistor. The direct
connection was enough when I was using a 1 nF primary capacitor. When
I increased it to 5 nF I had to add the follower. I added a 1 Ohm
resistor in series with the 100 Ohms for another output, at low voltage
but very low impedance.

Antonio Carlos M. de Queiroz