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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