Re: Capacitor Size and BPS

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Peter,

WOW! Very Impressive!!! The 6" coil IS amazing!! Sparks to certainly 
be proud of!

Well, I went through your specs. Hard to say what the power input is. 
I note you are not ballasting the MOT's, but you did mention 250V in, 
220V at variac at 20A, so I'm guessing if 4 MOT's are series'd, then 
output is about 10kV @ 567mA. That was with 92nF cap (MMC & rolled), 
so say about 7.3 tap on the 14 turn primary? The toploads are 
certainly "goodly" sized for the coil and I see slight breakout points.

When I input the above transformer data and then ARSG info for the 
9000 RPM motor (50 Hz), you are certainly at 1200 bps. In Javatc, the 
output spark length prediction for the RSG coil was 108", so I guess 
that actually is about what you are getting. I guess that is due to 
the 1380 joule*sec across the gap!

It doesn't appear to "me" that the gap losses have increased all that 
much (if at all) with a break rate 10 times the nominal 120 (or 100 
in your neck of the woods). I did notice a blower? Is that additional 
cooling for the thoriated tungsten electrodes?

Anyway, WOW again!
Excellent photo's and thanks for pointing me to your data.

Bart


Tesla list wrote:

> Original poster: "Peter Terren" <pterren@xxxxxxxxxxxx>
>
> For my high BPS coil, I used 4 series MOT's under oil probably 
> saturating with variac up high (or full).  1280 turns in 32 inches 6 inch diam.
> Note the cap is across the transformer, not the gap, unlike most
> people. Cap was part CD MMC and part rolled cap to total 92nF.
> Topload was double and big.
>
> I think it worked well because of the fast bps and big double top 
> load to prevent primary strikes.
> Details are here.
> http://tesladownunder.com/tesla_coil_6inch.htm
>
> Peter
>
> > Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
> > Hi Peter,
> > I've always been interested in these high bps achievements. Could 
> > you send me some basic specs on your coil setup? I would just like 
> > to know the transformer and cap specs if it's not too much trouble 
> > (I assume the coil is 32" length or near?).
> >
> > I agree with your last statement. The burst rate and it's affect on 
> > growth with comparison to input power may allow for other tradeoffs 
> > (like longer sparklengths with smaller cap size). Just curious on 
> > the specs if you have them.
> >
> > Take care,
> > Bart
> >
> > Tesla list wrote:
> >
> > > Original poster: "Peter Terren" <pterren@xxxxxxxxxxxx>
> > > My coil has best performance at 1200BPS (9,000rpm, 8 electrodes) 
> > > and achieves 8 foot sparks, 3 times the secondary length.
> > > The screaming jet philosophy works for me. Efficiency is difficult 
> > > to determine at >5kW at the time as I didn't have the true RMS 
> > > wattmeter that I have now. But that was a secondary consideration 
> > > to spark length. I am still not sure we really have a good idea of burst
> > > frequency and length to get optimal spark growth.
> > >
> > > Peter