Re: Combining several caps

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

Original poster: "Sean Taylor by way of Terry Fritz <teslalist-at-qwest-dot-net>" <taylorss-at-rose-hulman.edu>

 > We've acquired a NST (sec. : 8kV, 10mA at 220V, 50Hz) and so WinTesla
 > suggested we use a 4 nF capacitator.

 > What seemed the simplest for us is using 16 (C1) 1nF 2kV caps, placed in 4
 > parallel rows of 4 caps in series.

SNIP . . .

Well, there are a couple problems here.  First, the 4 caps in series will
total up to exactly 8 kV, where your NST is an 8 kV NST, and will actually
put out 11.2 kV on the peaks, plus the ringing in the primary tank circuit
will repeatedly reach a high voltage as well.  You'll need a cap rated for
at least 12 kV.  Second, 4 caps in series, while increasing the voltage
capability, will decrease the capacitance.  Four of your caps in series will
be 0.25 nF at 8 kV, so 4 strings of 4 will yield 1 nF at 8 kV.  You're best
bet for a cap right now would probably be a saltwater cap, easy to make,
cheap, and variable size.  Someone recently posted the Geek Group bucket cap
link, or you can search for it on google.  Good luck!

Sean Taylor