RE: Re[2]: Capacitor Size

["Tesla list" <tesla@xxxxxxxxxx>]

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


Hi Sebas:

There's no formula that can calculate the BPS of 
a static gap coil.  The gap firing voltage and 
the NST charging current dynamics are far too chaotic.

The only measurements that I have recorded were 
for my mini coil, using a 4kV/20mA NST, with 
120VAC/60Hz in.  The mains-resonant cap value for 
this NST is calculated to be .013uF. This NST has 
had some of its shunts removed for a 38mA 
short-circuit current.  Not sure if this affects the mains-resonant cap value.

Using a digital storage scope, I scoped the field 
coming off the secondary over a 400 msec interval 
with a scope probe hanging about 8 feet from the 
coil.  I tried 3 different cap sizes:
Cap	BPS
.012uF	297 BPS
.02uF	207 BPS
.025uF	157 BPS

I should also have pointed out that I could have 
achieved 120BPS with any of the cap values if I 
Variac'ed the NST voltage down, but no 
performance peak occurs at any reduced Variac 
setting - it's downhill all the way.

I've not tried it with my mini coil, but with my 
larger coil, I have found that at a low Variac 
setting, I have been able to achieve a 60BPS mode 
of operation that sounds distinctly 
different.  It seems to be stable for a few 
seconds, but quickly reverts to chaotic 
mode.  Must be those butterflies in Brazil.

Regards, Gary Lau
MA, USA.



> Original poster: Illicium Verum <sebas@xxxxxxxxxxxxxxxx>
>
>
> Hello Gary,
>
> Thanks for pointing out. I to thought a static
> sparkgap fired always at 120 BPS.
>
> Is there a formula to calculate the BPS of a SSG?
>
>
> I'm curious, what speed did you measure?
>
> Best regards,
>
> Sebas.
>
>
> Thursday, October 6, 2005, 10:08:55 PM, you wrote:
>
>
>  > Original poster: "Lau, Gary" <<mailto:Gary.Lau@xxxxxx>Gary.Lau@xxxxxx>
>
>
>  > Hi DC:
>
>
>  > I assume you meant to say "0.016 at 60 mA".
>
>  > Have you actually scoped a coil with a static gap
>  > that operates at 120 BPS? Every static gap coil
>  > that I've scoped ran at a far higher rate than
>  > that.  I probably could have achieved 120
>  > (chaotic average) BPS, but I would have had to
>  > open the gap to an unsafe setting.  Since I tend
>  > to use a 2X mains-resonant cap size, I would see
>  > an even higher BPS had I used a 1.57X cap.
>
>  > In my early naïve days of coiling I thought that
>  > 120 BPS was the natural and normal mode of
>  > operation for a static gap.  I know better now
>  > and don't wish to perpetuate that misunderstanding.
>
>  > Regards, Gary Lau
>
>  > MA, USA