Re: what capacitor for TC...other newbie questions

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Richard,

At 09:36 AM 7/7/2001 +0800, you wrote:
>What are the thoughts on metallized polyester?
>I have 4 .022uf -at- 16000vdc. These can be found at Allied Electronics:
>http://www.alliedelec-dot-com/catalog/pf.asp?FN=571.pdf
>
>Though it's a DC spec there is no polarity on these caps. No AC spec is 
>provided but it would be less than the 16Kv DC rating.
>
>

Polyester has a dissipation factor about ten times higher than
polypropylene.  This means that they will run about 10 times hotter given
the same RMS current.  Since Tesla coils are super hard on caps, this 10X
heating is a killer.  Tesla caps really need to me made from the lowest
dissipation factor materials available to have a chance of surviving in
this extreme duty.  Also, "metalized" caps have poor end terminal
connections that tend to burn out with 1000 amps spikes like Tesla coils
may create.  You really need metal "foil" caps that use solid metal foil
for the electrodes.  There is a list of known good/bad caps at:

http://hot-streamer-dot-com/TeslaCoils/MMCInfo/good-bad.txt
http://hot-streamer-dot-com/TeslaCoils/MMCInfo/mmcinfo.htm

We are very picky about the caps used in MMCs.  I try and test them pretty
hard*.  They have to be some of the best available.  They are not cheap but
the Geek Group's prices are very good!

*http://hot-streamer-dot-com/TeslaCoils/MMCInfo/GeekCaps/GeekCaps.htm

Cheers,

	Terry