Subject: TESLA CAPACITORS
From: richard.quick-at-slug-dot-org (Richard Quick)
Date: Tue, 27 Jun 1995 23:36:00 GMT
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Quoting Ed Sonderman:
ES> ... run into a problem with the capacitor. It is the one
ES> difficult thing to make at home. I did make two rolled
ES> capacitors using aluminum flashing and .0625 polyethylene.
ES> I did a good careful job building them. They both came out
ES> at .019 microfarads. They worked fine for a while until I
ES> finally got up to 12kv and tried to run them for several
ES> minutes at a time and they both eventually failed -
ES> punctured the dielectric. I am convinced that capacitors
ES> built like this (with .062 poly) will only withstand about
ES> 9.0kv for any period of time. If you use .062 you need to
ES> use two of these in series for 12 or 15 kv operation.
I certainly won't argue the point here. I have blown my share of
these, including one failure while the capacitor was wired in
series for high-voltage operation (and running a whopping 12kV)
when a flashover from the wiring leapt a connection.
ES> My problem was that I needed .019 mfds. So I used one
ES> capacitor at a time and eventually ruined them both. What I
ES> really needed to do was to build 4 of these and use them in
ES> series/parallel. Another option would be to use .093 poly
ES> but the finished value will drop down quite a bit.
Again I will concur.
ES> I calculated my cost to build these capacitors at about
ES> $90.00 each. This is about the time Richard Quick suggested
ES> buying a commercial made capacitor. I got quotes from four
ES> different companies. Condenser Products Corp. in
ES> Brooksville, Florida (phone 904-796-3561) provided the best
ES> quote and seemed to be the most knowledgeable. They built a
ES> custom capacitor for me for $185.00 including shipping.
ES> This is cheaper than I could have built it for, it is much
ES> smaller than 4 large upright home made capacitors and I'm
ES> sure it will take more abuse. The value is .025 mfd,
ES> 15,000v RMS AC rated for pulse discharge - Tesla tank
ES> circuit operation. It was tested to 33,000 volts. They told
ES> me today the price for this capacitor would be $220.00
ES> I just thought I would let everyone know about this.
ES> It may seem like a lot of money, but I think it is cheaper
ES> in the long run and they do build a great product.
I too own a couple of capacitors from Condenser Products, and I
will agree that these are top flight units rated (though not
guaranteed) for Tesla work. They can be very cost effective (both
in construction time and money). However, consider another aspect
of coiling as well, versatility.
If you go out and buy a single hefty commercial capacitor you are
really locked into a specific range of frequencies and power
levels. Purchasing multiple commercial capacitors of lower values
is not cost effective when dealing with new units. Your higher
frequencies use less capacitance, are safer for many experiments
and test setups, and are difficult to reach with a large capa-
citance. By constructing two, or even better four, homemade
capacitors you can span a greater range of frequencies than can
be easily obtained with a single commercial capacitor. If you
then add a commercial capacitor to your stock of homemade units
you have the ultimate in frequency and power ranges, reliability,
... If all else fails... Throw another megavolt across it!
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