Re: Glass Capacitor

To: tesla-at-pupman-dot-com
Subject: Re: Glass Capacitor
From: "Bert Hickman" <bert.hickman-at-aquila-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Wed, 22 Mar 2000 21:52:12 -0700
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Tesla List wrote:
> 
> Original Poster: "Scott Stephens" <Scott2-at-Mediaone-dot-net>
> 
> Who has used plate glass for their capacitor, what specs and what results? I
> remember someone complaining a while back it was very heavy. I'm considering
> stacked plates with aluminum foil in between:
> 10" x 10" with 1/4" on the edges painted with corona dope
> .05" or .1" thick plate glass for 12KV?
> 
> Thanks,
> 
> Scott

Scott,

I made plate glass caps when in high school (they'd just invented glass
back then... :^)). I used double-strength window glass. Found that these
were very pretty to watch with the heavy corona glow all along the foil
edges. They were also prolific ozone generators! When using them as tank
caps in a TC, the result was always the same - after a minute or so of
running, a hot spot formed (usually at a bubble, or imbedded impurity in
the glass), and the glass then arced-through at this point. The affected
plate then usually shattered (sometimes quite forcefully), often taking
out neighboring plates. 

The losses were horrendous, the tuning point very broad, and the coil
output performance was wimpy. Go for an MMC!  :^)

-- Bert --