Re: Main spark gap across one or both transformer legs?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,

At 03:35 PM 10/3/2006, you wrote:
> Hello, I have two questions. I am in the middle of gathering 
> materials and designing my first coil SGTC.
>
> What is a better design....having the main spark gap across the two 
> transformer's legs...and have the cap bang on 1 leg...or have the 
> spark gap connect across 1 leg and have the cap bank connect across 
> the 2 legs of the transformer?

"Always" put the spark gap across both legs of the transformer.  When 
the spark gap shorts, it will tend to keep the high frequency stuff 
out of the NST.


> Also, if I plan on using a transformer around ~9kv 30mA   is it 
> completely necessary to have a full protection filter such as 
> <http://www.classictesla.com/download/NST_Filter.jpg>http://www.classictesla.com/download/NST_Filter.jpg 
>
> or can I just make two chokes, wrapping wire around an extremely 
> small diameter PVC pipe along with a safety gap?

Don't bother with chokes since they are useless.  A safety gap will 
be fine.  It really helps if you use an "LTR" cap size of 
13.3nF.  That will give the best arcs and prevent the NST from going 
over voltage.  The fancy filter is "cool", but you can live without 
it if you are careful.  If you do "everything right", the safety gap 
is probably not needed.  But if something messes up you need 
it...  "Never use" the "resonant" cap size (8.8nF in your case).  It 
has killed countless NSTs!!!!!!!!

Cheers,

        Terry



> Thanks.