Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
Hi Tomas,
Many capacitor dielectrics will heat up with high frequency. Caps
should be selected for their rep rates, lead construction
techniques, dielectric material, rms current capability, voltage,
etc. Even though many caps are rated for high voltage, they are not
rated for high frequency. It's best to use caps the coiling
community has tried and determined good for coiling. You've probably
seen on the TCML the mention of Cornell Dubilier MMC's. There are
Cornell's 940C series. They are axial lead film caps which use
polypropylene as the dielectric (excellent for high frequency) and
they have a high dV/dt rating (high peak currents). The MMC is very
simple. It's just a cap bank built of several small capacitors which
are series connected for the voltage rating. Strings are then
paralleled for the capacitance required. That is at least the
basics. You can play with MMC configurations here.
http://www.classictesla.com/java/javammc/javammc.html
I just saw a post of someone looking to do a bulk buy on MMC's. I
usually buy caps as needed and only when it's right for my pocket
book. If I need caps, I'll likely contact Dr. Resonance. He uses
them for his own business and also puts in requests on his order for
those on the list who also need caps. This increases his quantity
break down pricing if the extra request quantity is high enough (if
the quantity is not high enough, he won't get the pricing break.
Standard operating procedure for those who deal with this stuff on a
daily basis). However, his MMC needs will vary as will list member
needs. Contact Dr. Resonance for pricing. I know he's currently
looking for coilers in need of caps.
Take care,
Bart
Tesla list wrote:
Original poster: Tomas Stankevic <Tomas.Stankevic@xxxxxxxx>
Hi, today I tried my first Tesla Coil. It's 65cm high (secondary),
it is powered by 10kV 20mA transformer (a bit too low for him). I
used 25kV, 22nF capacitor. It worked perfectly for about 20
minutes, then capacitor went hot and then it was dead. Why??
transformer power supply is 10kV and a capacitor is suitable for
25kV! I know about a resonance... but... :( What capacitor should I use then???