RE: choosing the right capacitor, secondary and topload

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

Hi "Webmaster":

For your NST and a 120BPS sync RSG, the "book" value for Cp is .054uF.
With my 15/60, I found that 48% larger than book value yielded the
biggest bang, so for your case, between .054-.083uF.

It's difficult to generalize about correlating secondary parameters vs.
performance.  To a degree, low frequencies and the parameters that go
that way improve performance.  Often, "bigger" is better.  But there are
limits beyond which bigger gets worse.  Only trial and error can tell
where that point is.

The same is true with toroid size, bigger being better, up to some
ill-defined point.  Yes, Vs will diminish with increasing Cs, but if you
measure performance in terms of spark length, Vs is of academic interest
only and unimportant in terms of maximizing spark length.

Regards, Gary Lau
MA, USA




> Original poster: Crystal Clear Solutions <webmaster@xxxxxxxxxxxxxxxx>
>
> I have a 15kv/120ma NST, primary 120v/60hz
> 6" secondary 29.5" tall 22g wire
> sych gap 120 bps
> assume all protective circuits/safety gaps/filters are in place
>
> I have read about Cres and Cltr.  What is the best Cap to choose for
> the largest sparks? I've gotten Cres = 0.01uf and Cres for a sych gap
> = 0.026uf and Cltr = 0.055uf.  Do these sound close?
>
> Here is a second question.  If my Cp is fixed and I can retap my
> primary at any point to adjust for a new resonant frequency (Fres),
> how will varying the height/wire size of my secondary affect spark
> length?  Will increasing the Ls and increasing Fres yield bigger
> sparks?  Is there some trade-off?
>
> Third question: If one assumes Cp fixed and I can retap primary at
> any point to adjust for new Fres, how will increasing the toroid size
> affect spark length?  From my reading increase the toroid size
> increases Cs so Fres will go down.  Lp will have to increase and this
> will drop the secondary output voltage.  However, increasing the
> toroid size, by increasing Cs will allow for a greater breakout
> voltage which should increase the spark size.  Where is the "sweet
spot"?