RE: Coil Woes

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

Original poster: "Lau, Gary" <gary.lau-at-hp-dot-com> 

Since Cres*1.2 is closer to Cres than is Cres*1.6, I would think what
you advocate world be MORE likely to be vulnerable to mains-resonant
rise than the higher value?

With a static gap, a smaller cap will result in a smaller bang size and
faster BPS, not sure exactly what the impact would be on streamer
appearance, though certainly shorter.  Quite possible that they will be
brighter despite being shorter.

I know that I recently swapped my 7x30 toroid for a 6x24 toroid.  The
bigger toroid would only breakout reliably from a breakout point and
delivered my longest streamers.  The smaller toroid didn't need a point
and readily broke out all over the toroid with shorter streamers,
probably similar to what you were saying.  This was with my 15/60, sync
RSG, and a Cres*4.0 cap in both cases.

Gary Lau
MA, USA


 > Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com>
 >
 >
 > I have always advocated Cres value * 1.6, however, lately, I'm
changing my
 > thoughts on this value.
 >
 > The 1.6 does give the longest sparks, however, the nature of the
sparks are
 > "stringy" and not active and "dancing" off the toroid.
 >
 > Lately I've been using Cres * 1.2.  This value reduces the chances of
 > resonance between the supply NST and  capacitor bank while producing a
very
 > pleasant and active spark field that literally "dances" off the toroid
 > seeking ground.
 >
 > Try this experiment yourself using both values 1.2 and 1.6 and you
will see
 > what I mean.  The 1.2 value has more charging current which produces
better
 > looking discharges.
 >
 > For us, it's back to 1.2 * Cres for the best looking spark discharge.
You
 > only loose a few inches.
 >
 > Dr. Resonance
 >
 >  >  >
 >  >  > My question today concerns transformer to capacitor match. I
input the
 >  > data
 >  >  > into three separate programs and got three completely different
 >  >  > answers.  The values of the transformer are as follows; Input
120 volts
 > 60
 >  >  > Hz and the output is 12,000 volts at 30-ma. NST. Initially I
built an
 > mmc
 >  >  > of 0.007 uf , 20,000 volts. Several people have suggested that I
need a
 >  >  > 0.01 uf cap to power my coil. How is this value obtained?
 >  >
 >  > One 12KV 30ma transformer will resonant at 60 Hz with a 6.6 nf cap.
 >  >
 >  > Cres(nf) = 10^9/(2*pi*line_freq*XL)  where XL ~= 12000V/30ma
 >  >
 >  > If is common practice to avoid resonant charging by using a LTR
(larger
 > than
 >  > resonant) cap.
 >  >
 >  > for static gaps Cltr = 1.6 * Cres (give you about 120BPS)
 >  > for SRSG        Cltr = 2.8 * Cres  (at 120 BPS)
 >  >
 >  > 0.01uf would be 1.5 * Cres.
 >  >
 >  > As you add more 12K/30 NST, add 0.01 for each extra NST.
 >  >
 >  > Gerry R.
 >  >
 >  >
 >  >
 >