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Re: BIG resonance! - thoughts...
In a message dated 99-04-06 04:37:16 EDT, you write:
<< >
>This weekend I built a larger toroid and had trouble getting breakout, even
> with a bump. I tried opening my gap, (0.280" to 0.336"), this helped
> somewhat but still no breakout without the bump. Then I thought I might as
> well try using my larger tank cap, (0.011uF to 0.017uF). Lo and behold,
> Breakout! The cap, (0.017uF) that wouldn't work before now works! It seems
> that even though the 0.017uF cap doesn't resonate as well with the
> transformer as the 0.011uF cap the 0.017uF cap in concert with the wider gap
> is able to drive more energy through the system. I'm getting larger
> discharges that I ever have.
Jon, all,
The wider gap gives the large cap the extra time it needs to charge up.
I use a .0147uF which works well. In general, the largest cap you can
use, and successfully charge to full voltage, will give the best spark
output. There's a danger though; you might be firing every 60Hz, instead
of every 120Hz, this might let the voltage build too high and ruin the NST.
In general wide gaps tend to destroy NST's.
I had a 12kV, 30ma NST one time that was especially robust; it was
able to charge a .0087uF cap. THis gave a good output of 40" using
static gaps. A typical NST of that rating cannot charge the .0087uF
cap, but only a .0073uF or so. THis reduces the spark output to about
36" or so. But by using a sync rotary, I was able to bring the spark back
up to 42", and also *protect* the NST to some degree in the process,
and obtain a much smoother and better overall result.
> It seems like the new toroid, (6" x 28", 35.43pF), is about the maximum
size
> that my coil will support. I'm now getting some turn to turn arcs near the
>top of the secondary.
Probably. If you're toroid is 3" or more above the secondary, you could
try lowering it about 1" and it might stop the turn to turn arcs, but it
might
reduce your spark output by 1" or so also.
John Freau
>Jon Rosenstiel
>>