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Re Rolled poly cap (poly source)
>Original Poster: Sebrf-at-aol-dot-com
>
>Hi
> My son and I (emphasis on the I ) have decided to upgrade our
>Tesla circuit by replacing the capacitor and primary coil. We decided to
>build a rolled poly cap. using Gary Lau's design as stated on his web
>site. My question is, Where do / can I find poly that thick. The best I
>can come up with is 6 mills which would require us to use 12 sheets per
>cap. , 2 caps. in series. Hopefully I can place both caps into the same
>PVC pipe. Since I don't live to, to far from Gary (RI) , I thought he
>may have a suggestion. Off list or on list, It don't matter.
>
>Rich Sebzda
>Your friendly nieghborhood catscan repairman
Hi Rich:
The short answer is that I phoned Cadillac Plastics, in Woburn MA. They
can get any thickness you want. I think the 4'x8' sheet of .04" poly
cost me $25 plus $11 tax & freight.
The longer answer is, you are aware that that cap failed, right? Now for
some reason, possibly poor quenching of my single gap, my coil seems to
be a lot harder on caps than others I hear of. My commercial Fair Radio
Sales cap runs warm while others report no such thing, so your milage may
vary. What voltage is your power supply?
I have found that attempting to roll many sheets of thin poly, in
addition to being a major pain to cut, is extremely frustrating. Plus,
in my extended-foil design, I think it just won't work. The layers will
shift and with the foil extended on both sides, you won't be able to
detect or correct for the shifting.
While no one seriously considering the construction of a rolled cap wants
to hear this, I feel obliged to add my voice to the chorus. If I had
that cap to do over again, I would have made three identical units in
series, perhaps with 30 mils poly per cap. I think mine failed due to
corona at the edges of the foil, despite vacuum pumpdown and mineral oil
backfilling.
Good luck!
Gary Lau
Waltham, MA USA