RE: Best cap size for a sync gap

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Lau, Gary" <gary.lau-at-hp-dot-com> 

Hi John:

I don't have another 15/60 NST to compare against mine, but I do have a 
pair of 15/30's.  It would indeed be interesting to compare results.  My 
to-do list is growing daily, it may be a long time before my coil ever 
produces sparks!

BTW, I'm not sure I saw the voltage reversal mode you spoke of at any time 
with all of the differing Cp's.  I did note that when the phase was way out 
of whack, I would see the gap firing at 60 BPS, with the voltage 
necessarily reversing polarities, but I assume you were talking about 
something occurring at 120BPS?  The mains current at 60BPS was 
breaker-tripping!

Regards, Gary Lau
MA, USA


 >Original poster: FutureT-at-aol-dot-com
 >
 >Gary,
 >
 >Interesting results.  It would be interesting to do the same type
 >of experiment using other NST's.  I suspect that various NST's can
 >behave very differently than others.  I've seen the need for widely
 >varying phase settings for different NST's.  Some give their max
 >output when firing at the peak voltage.  Others give their utmost
 >when firing after the peak as you mentioned.  If the NST you used
 >is the one that you usually use (the one you re-potted), it may
 >happen to be a robust NST.  Results at 140V tends to be somewhat
 >different in nature than at 120V, but I don't have good records
 >of what I did in that area.  In any case I think the ideas about
 >"2.8 x the resonant value", etc. are just guides.  What's really
 >best will depend on the particular NST I think.  I've found
 >that NST's vary widely in their characteristics across brands,
 >and across voltage/current ratings.  Some NST's are also more
 >prone to problems of running in the notorious voltage reversal
 >mode.
 >
 >John