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Homemade Capacitor death.




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From:  David Huffman [SMTP:huffman-at-FNAL.GOV]
Sent:  Monday, February 16, 1998 9:55 AM
To:  Tesla List
Subject:  Homemade Capacitor death.

Hello Group,
I have to confess my own ignorance to maybe help someone else. I fired my 8"
coil last night for the first time with my homemade caps. After tuning I
began to crank to variac up and was happy to see the sparks grow to about
30". It seemed pretty good for just 12KV -at-60 ma input.  It only lasted about
10-15sec. however before failing. I had made 3 identical caps at about 80nF
each and was running them in series. The caps started out flat. The layering
was foil 5-mils paper, 8-mils poly, 3-mils paper, 8-mils poly, 5-mils paper
and foil. The error occurred when I folded the flat layers up to fit them in
a PVC pipe. I didn't recognize that the outer layer of foil of one electrode
was separated from the other electrode by a single paper width. The
beginning and ending stack should have had several layers of insulation.
I still can't believe I did this three times and never thought about what
was going on!
I took a bath in transformer oil shortly after the failure and repaired one
of the units. The big problem is trying to fit it back in the container
since it has swelled up with oil.
Learning what to do by doing all the things not to do.
Dave Huffman