Re: Best location for spark gap

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

Original poster: "Harold Weiss by way of Terry Fritz <teslalist-at-qwest-dot-net>" <hweiss-at-new.rr-dot-com>



 > Original poster: "J. B. Weazle McCreath by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <weazle-at-hurontel.on.ca>
 >
 >
 > At 06:08 PM 06/01/03 -0700, you wrote:
 >
 >  >Original poster: "Lau, Gary by way of Terry Fritz <teslalist-at-qwest-dot-net>"
 > <Gary.Lau-at-hp-dot-com>
 >  >
 >  >If I may be the devil's advocate for a moment...
 >  >
 >  >I fully agree that when using NST's, having the gap across the power
 > supply >lowers the high frequency stresses applied to the NST.
 >  >
 >  >But when using a power supply that is not current limited - a
distribution
 >  >or potential transformer, I wonder if the placement of the gap affects
the
 >  >ballasting requirements?  I've never used such a power supply.  Has
anyone
 >  >who has tried it both ways?
 >  >
 >  >Regards, Gary Lau
 >  >MA, USA
 >  >
 >
Hi All,

Tesla said that the parallel system is very hard on components, but it did
give longer sparks.  Think of it as a high rate quartershrinker firing into
the primary.  I think if driven with a pig, you could keep adding
capacitance up to the point that the pig couldn't charge it anymore with a
given break rate.  I might be wrong on this.  On my older coils, I could add
capacitance up to a point, about the area of an LTR cap, before performance
would start to drop off or stay steady with further addition.  This was with
NST powered coils (6-9/30) that used leaky foil/sw caps.  The corona off the
caps severely cut performance, so that may account for a bit of the drop
off.

Quenching of the gap will be most important.  As I see it, we want to dump
all the energy to the primary without it returning back to the cap.  This is
probably the reason I would get a 24" streamer at powerup, which immediatly
dropped back to 18" for the rest of the run.

Something that might be useful in this circuit, is a SCR or triac controlled
charging.  What would be needed is to only allow charging during the first
90 degrees and from 180-270 degrees.  At all other times the charging system
would be off.  It just occurred to me that a DC/triggered gap system would
work well too.  A DC/trig would provide faster breakrates that AC.  In any
case the cap is going to kick back at the charging system so be prepared.

David E Weiss