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RE: Coil Woes



Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi,

A resonant value may give longer sparks if it resonates the primary beyond 
the transformer's ratings.  The idea of LTR is to get the most power out 
while keeping the transformer voltage within it's rating.

Cheers,

         Terry

At 01:47 PM 10/8/2004, you wrote:
>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.
> >  >
> >  >
> >  >
> >