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Re: Sold state IGBT disruptive coil spark gap idea

Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi John,

Interesting, on my static gap TC, I scoped the primary and most bangs were 1st or 2nd notch quenched. Now that Im using a rotary, its not as obvious on the scope. I dont remember seeing any subsequent notches even though the mechanical dwell time would support it. Maybe this is because the gap separation is so small that voltage at the rsg gap doesnt change noticably. Maybe I need to monitor the voltage at the cap/primary node. If what you say is true, then maybe this 1st notch quenching is not as important as it seems.

I wonder how accurate JAVATC's predicted k is and if this can be a basis for comparing different coils and avoid the measurement.

Gerry R.

Original poster: FutureT@xxxxxxx
In a message dated 4/30/06 8:49:09 AM Eastern Daylight Time, tesla@xxxxxxxxxx writes:

CASE 2: Streamer formation - no ground hit:  A certain percentage of
the energy making it to the secondary will go into the streamer
leaving the remainding energy to be transfered back to the
primary.  One could create a series function to see how many
transfers it takes until the existing streamer can not be sustained..
>From this, one can figure the ratio of the total streamer energy to
initial primary energy (efficiency).  One can figure the efficiency
for 1st, 2nd, 3rd notch quench, etc, and figure how may primary
notches until the streamer is no longer sustained.


It's possible that the streamer length is determined more by
the peak initial energy transfer, than by the overall amount of
energy transfered to the streamer.  This would explain why
most folks obtain longest streamers with tightest coupling,
despite more notches occuring using such tight coupling.
In other words a less efficient (less total energy transfer)
setup may actually give longer streamers....  Assuming that
more notches actually results in less total energy transfer.  Then
there's Bert Hickman's suggestion that subsequent energy transfers
back to the secondary (during one bang) actually help the sparks
to grow.  But in any case a disadvantage of delayed quenching is
that it gives the caps less time to charge before the next bang.

In contrast to much of what I say above, Dr. Resonance has obtained
his longest streamers using a looser coupling.  Looser than what
his coil can physically withstand without getting racing sparks.
Maybe the special glyptol coating he uses permits him to
tighten his coupling far beyond what most folks can achieve
without getting racing sparks.  Maybe this is what has permitted
him to see what others have failed to see.  To determine what's
happening, it would be necessary to know the measured
coupling of the Dr.'s coils to compare with other folks' coils.
It would also be necessary to use the same method for
measuring the k of the various coils, or at least a method that will
give the same results.  Some coupling measurement methods
give incorrect results, making the coupling appear tighter than
it actually is.  This is especially true at tighter couplings.