Re: Variable capacitor

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Harold Weiss by way of Terry Fritz <twftesla-at-qwest-dot-net>" <hweiss-at-new.rr-dot-com>

Hello all,
I have built a Cu/PVC tubing variable cap somewhat similar to what you
describe.  It did not work!  PVC has too low a puncture voltage.  My 6/30 NST
could breakdown the 3/4" PVC tubing dielectric.  You need to go with Acyrlic or
polyethelene in oil.  The cap I made used a 3/4" Cu patching pipe over 3/4" PVC
pipe.  The repair pipe was 12" long.  For the other plate, I used 1/2" Cu
pipe.  I measured this for capacitance, and was able to get 100pF.  This cap
failed as soon as I applied power.  
 
Thanks for bringing this idea back up!  Now that I am older and wiser about
materials, I can bring this cap to life. ( Isolated servo system.  Hmm.. where
did I put those motors?...........)
 
David E Weiss