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RE: Capacitance
The widely-used method of sizing a capacitor such that it becomes
mains-resonant with the NST secondary should be used merely a general
guideline. While a mains-resonant cap will behave uniquely (ring up to
extremely high and damaging voltages) if there is no spark gap to discharge
it on every half-cycle, a mains-resonant cap does nothing special in normal
Tesla coil operation. With my 15KV/60MA NST, a mains-resonant cap would be
about .01 uF. While this did work quite nicely (51 inch arcs), I've since
found that with a .02 uF cap, performance is even better (60 inches).
When you were adding and removing caps, I assume you were re-tuning the
primary each time?
Regards, Gary Lau
Waltham, MA USA
-----Original Message-----
From: Tesla List [mailto:tesla-at-pupman-dot-com]
Sent: Friday, December 10, 1999 12:51 AM
To: tesla-at-pupman-dot-com
Subject: Capacitance
Original Poster: "Spud" <spud-at-wf-dot-net>
Hey again. I have been experimenting with the capacitance
on my coil
mainly because I got a new power source. It's a 15kV/30ma
neon. They are
almost brand new so I don't want to depot them to take
shunts out, but I
have several of them so is it a good idea to connect two of
them and run
with 15kv/60ma? Anyway, my capacitors were .007uf when I
was using my
12/30 power source. I went back and calculated the
capacitance for a 15kv
transformer and it was .005uf. I went back to and added
more caps to make
it exactly .005uf. However, this made the performance of
the coil
considerably worse. When I took capacitors back off, I
noticed the
performance got better with each one I took off, even past
.007uf. So
what's the deal? What kind of capacitance do I really need?
Thanks,
Ryan