Re: Capacitor help

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

Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net> 

Hi Dan,

13000V is just at the peak voltage of 9kv rms.  .009uf is the resonant
capacitor (Cres) value of your NST which means that the output voltage could
go 5-10 times higher (depending on the Q of your NST) if allowed by the
safety gap and main sparkgap (called resonant rise).  Often NST's put out
more than their rated voltage unloaded.  Personally, I would design the MMC
for about 18000V (9  2000Vdc caps per string) and use a static gap LTR value
of Cres * pi/2 or about .014uf in your case.  This LTR value will limit
resonant rise and give you about 120 BPS.  All of my calculations was based
on 60Hz line so if you have 50 Hz line Cres gets scaled up.  The CDE 942C
series capacitors are very highly regarded for this application.  You should
probably use a TC program like JAVATC and input your coil design.  The
program will say what the peak current will be and that help you in
determining how many strings you need.

Gerry R
Ft Collins, CO


 > Original poster: Bob81818-at-aol-dot-com
 >
 > Hello, I'm part of the way done with building my first coil. I've sat here
 > in front of the computer for hours trying to make sure of all the right
 > numbers and measurements and such. I was just wondering if someone could
 > tell me if a .009uf 13,000v capacitor will be enough for a 9kV 30mA NST.
Or
 > does that sound like someone who stayed up too late working on this thing?
 > Thanks everyone.
 >         Dan
 >
 > Oh and if that does sound about right, would anyone be so kind as to help
 > me out with what kinda caps I should use? I wanna be difficult and build a
 > MMC, I think they look cool and they seem more accurate. Thanks again.