Prior to designing my own polycap, I wanted to buy one and sent the spec to
some companies. The main problem - besides the price of course - was the
100% voltage reversal, that shortens the expected life drastically.
I wonder, whether the use of a HV bridge rectifier between xformer and main
gap would help, to keep the cap alive a little bit longer. In each arm of
the rectifier one could use e.g. 3 HV diodes from microwave ovens in
series, each parallelled by a resistor and a small cap. Another possibility
would be diodes with an avalanche characteristic, which require no
One drawback could be a material migration in the main gap.
Did somebody try this circuit?