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Re: Results of new single static gap

Hi Richard and All,

This post was very interesting to me since I am now studying these things.  

	Apparently, small-spaced multiple gaps can be made to provide excellent
quenching in that the many small gaps will stop conducting at the first
notch and trap maximum energy in the secondary.  However, that is not the
full story. 
 
	If there is poor air flow through the gaps, the firing voltage will be
low.  The very first cold gap firing is perfect and fires at the peak of
the cycle but then the gap will heat and the firing voltage will decrease
to maybe 70% of the maximum voltage available (that decreases available
energy by 50%!!).  This causes the firings to occur a few milliseconds too
soon (which can play havoc with precise computer designed coils like mine
:-))  If the gap fires too soon in the cycle, the charge timing gets all
screwed up and basically energy is being eaten alive by the poor charging
circuit's performance under these conditions.  

	Now if we have a way to cool the gap by blasting it with air or by a
rotary arrangement, then the gap should fire much closer to the peak of the
charging cycle and the performance should improve dramatically.  Perhaps
this is why blasting air through the gap helps performance, not so much
because of good first notch quenching but because the gap is firing at
higher voltage levels closer to the peak of the 60 Hz charging voltage.

	I suspect that an optimal gap will be able to fire the gap right near the
peak of the charging cycle and also provide good first notch quenching with
relatively high coupling.  Perhaps the forced air cooled multi-gap gaps
will do this or a "refined" rotary system.  A combination gap may also do
the trick as well.

	I personally am not convinced that a very high break rate is important but
I still have much to learn about all this.  After starring at scope
captures of these waveforms for a few hours this evening, I see many things
that need investigation and improvement.  The gap is not doing what I and
the computer models want it to do (obviously, the computer and I are right
and the gap is what's wrong :-)).  
   
	I may be restating known principles here but I think the subject of what
goes into a good gap, what factors are important, and why is poorly
understood by most.  I feel that once the principles are understood, we can
concentrate on how to turn these principles into simple reliable gaps
designs that have excellent performance.  We now have the analysis and
measurment tools that allow use to get very good REAL data as to what is
going on in our gaps (and at least in my case, it ain't pretty).  Any
further insight, hints, etc. by you or others who have been down this road
are very welcome.  

Thanks,

	Terry Fritz  (Yes, I really do read the posts too :-)) 



>From: Richard Hull <rhull-at-richmond.infi-dot-net>
>
>At 10:33 AM 8/29/98 -0400, you wrote:
>SNIP............>
>Sorry for the delay,  I've been out of town.
>
>The static gap fires strictly based on spacing per unit gap.  Thus you can
set
>it to fire much more critically than most any rotary gap although with
>considerable jitter.  Who cares though, right!?  It just doesn't mean beans.
>
>The theory is that we want, ideally, two pops per power freq cycle or we are
>accepting less than the full capacitor energy....  Thus. the lock in on sync
>rotaries.  It is totally un-important.  Those who have been around doing
instead
>of theorizing will have long ago realized it is the time ordered energy
>throughput that makes sparks and not max energy fired between huge
expanses of
>time.  This time interval is well in excess of most significant air ion
>lifetimes.  Thus, the sparks might not extend on a 120 BPS sync rotary to the
>same distance a similar powered 400bps system with smaller cap might.
>
>The static gap can be made to fire four times per half cycle quite easily
with
>good design.  These four pops can be anywhere on the sine.  Most long
sparks are
>created when the firings occur between 45 and 135 degrees into each half
cycle.
>Four pops anywhere in this region will supply a hell of a lot of repeated
energy
>to any spark channel.  The blasts will never ever be evenly or temporally
>repeatedly spaced!!!!!!!!!   Again, who cares!?
>
>I have managed to achieve static gap 6 firings per half cycle in small
systems
>with an occasional 8 pops per half, but it is tough to go that fine
without lots
>of gaps.  Also the small capacitor demanded limits input power, regardless.
>
>I have fired systems from 30 degrees to 150 degrees per half cycle  They all
>worked great.  Each system has a unique characteristic with advantages and
>disadvantages.  In most systems I have at least 1 or two pops per half
cycle at
>or very near the peak quadrature points.  If not, then I am guaranteed two
pops
>between 80 and 110 degrees in each half cycle, which for spark purposes,
might
>be bettter!!!!
>
>The bottom line is that no static gap system will consistenetly fire at
just the
>points you would like, but the time ordered average is real close.  Try
>splattering you firings all over the sine.....you'll like it.
>
>Richard Hull
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