Re: Homemade Plate Caps.

>I started calculating the place capactiance I need.   Approxia.  0.0106uF 
>-at- 15kV RMS.   I have a sheet of polyethelene that is 10' x 100' 6 mil. 
>Does anyone know the Breakdown voltage per mil of this material. 
>I keep seeing different numbers.
>Matthew Klueppel
>Software & Electronics Engineer

Matt, I've built six poly caps using 62 mil thick poly.  Input voltage was 
9,000 volts (several neon transformers paralleled).  Eventually every one of 
the caps failed.  I have built a 90 mil cap, and it has held up ok.  For 
15,000 volt input, I'd recommend at least 90 to 100 mil thickness, maybe 120 
mil, but it will take more plates to make up for the loss of capacitance.  
Also, using several thinner sheets of poly to make up each layer of 
dielectric is much better than a single thick layer - mush less likeyhood of 
a puncture.

I'm tearing my six blown caps apart and will rebuild them from 62 mil to 124 
mil layers.  I don't expect future failures.