Notes on PlasmaSonic II - Initial Set-up

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Original poster: dhmccauley-at-spacecatlighting-dot-com 

I've finished my first two PlasmaSonic II boards and have successfully
tested both with audio.  The VU meters work great and performance
is excellent.

Just a few notes to add to the set-up and operation of the PlasmaSonic II
boards.
This is for push-pull mode (Audio Modulation) only.

1.  Adjust FREQ (R26) to the resonant frequency of your secondary.

2.  Adjust BIAS (R24) until duty cycle is approximately 18%.

3.  Measure voltage at pin4 of U21 (TL494).  The measured voltage should be
about 1.4V to 1.5V

Also, note that if no audio source is connected, noise may enter pin4 of
TL494 and affect spark output performance.

This will give you good results providing you use a standard line-level
audio source (high impedance RCA type) from a CD-player or
similar.

You will have to adjust BIAS (R24) to fine tune audio levels.  If audio
starts clipping, then you want to either reduce level of audio, or
back down the duty cycle a bit using BIAS (R24).

Dan