Re: transformer caps?

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Tesla729-at-cs-dot-com>

In a message dated 4/14/02 7:22:43 PM Pacific Daylight Time, tesla-at-pupman-dot-com 
writes:

<< I have a 15,000 kv NST and am building a Tesla Coil.

Hi Adam,

First, I think you mean a 15 kv NST, not 15,000 kV NST. 15,000 kV would
be 15 MV ( 15,000,000 volts). 15 kV = 15.000 volts.

 
< I was looking on ebay and
< found some 
(http://cgi.aol.ebay-dot-com/ws/eBayISAPI.dll?ViewItem&item=1721670681)
< and i was wondering if these would work in my Tesla coil. If not, could 
someone
< tell me what i need.
< Thanks
< Adam >>


These look to be the ceramic disc type capacitors are usually quite lossy
to the generated RFs of Tesla circuits. And since they are lossy, they tend
to heat up and this often caused their capacitance(s) to drift which can lead
to de-tuning. I can't find their capacitance rating on the ebay page but I'm 
pretty sure that if they are seried together, their total capacitance would
be too small to be practical for all but the tiniest coil. 

On thing you need to realize is that just because an ebay seller uses the
word "Tesla" as an adjective keyword for his product, that dosen't in any
way mean that it would be of any use whatsoever for a Tesla coil. Caveat
Emptor (spelling?) or BUYER BEWARE! Many sellers will use the "Tesla"
keyword to attract us coilers to their page when they're really trying to get
rid of useless junk (at least from a coiling standpoint) and make some 
money doing it.

If you're a beginner coiler then I would suggest looking into the Geek
Group multi-mini-capacitors (MMCs). They are rated at .15 uFD at 2000
volts each, I believe, and are perfectly suitable for the rugged environ-
ment of Tesla use. I think they run about $3.50 each and can easily be
series-paralleled for the total voltage and capacitnace that's required. 
A single NST sytem will probably only need a single series string of them
( example: 15 in series will yield .01 uFD or 10 nFD at 30 kV which is
probably sufficient for an LTR 15/30 NST system in both voltage rating
and capacitnace) And that would only be $52.50 plus shipping. I'm let
"Duck" take it from here :-) 

If you can't afford the MMCs, then you could built the salt water caps
out of old soda, beer, or wine bottles for a little of nothing. I think the
Geek Group has some good info on this, too.

Spark Safely,
David Rieben,
Memphis, TN, USA