Synchronous rotary gaps (srg)
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>From mmdf-at-wwnet-dot-com Thu Apr 25 01:13 MDT 1996
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Date: Wed, 24 Apr 1996 20:56:20 -0700
From: Skip Greiner <sgreiner-at-mail.wwnet-dot-com>
To: tesla ml <tesla-at-grendel.objinc-dot-com>
Subject: Synchronous rotary gaps (srg)
Richard Quick and the group
To kind of answer your questions
I have never personally run a good quenched static gap and in particular
I have not run one on my present setup.
Being an engineer and I know that many in the group are engineers I have
always liked things nice and neat. I know that static gaps work well and
you in particular have taken the art of static gaps to a very high level,
and your explanation of how they work is well accepted. It has always
seemed to me that there is a lot of reliance on the air in the gap and
hopefully a lack of debris. Alas, air changes temperature, has humidity,
and varible pressure and even may have impurities which can change when
the gap fires. One thing I have never understood about static gaps is how
many firings per cycle are expected when using a neon and this discussion
only involves neons since I have never had the pleasure of running a pig.
If there is only one then we would want it to be at the voltage peak, but
if more, then what? The voltage will certainly be at less than the peak
and then comes the discussion as to how much power are we actually
transferring to the TC and how can power be maximized.
With a srg I have complete control. I can set dwell time, firing point,
firings per half cycle. By setting firing point I control the maximum
voltage which the cap sees and also the resonant charging voltage which
the neon sees. I mentioned in my previous post that since going to srg
I have not lost a neon or a cap. Surprisingly the gaps become worry free.
I use .75" aluminum rod to hold the .25" or .31" brass pin contacts
which only get a little warm after 5 minutes of running . The matching
contacts in the linen or canvas filled phenolic rotor wheel are cooled by
the rotation in the air and they get hot but do not burn the phenolic.
These things automatically quench so no strange phenomenon appear.
The scope traces look like they came out of a text book.
There is only a little erosion and the contacts need dressing or
adjustment after about 30 minutes operation. I use motors that I have
found for about $12.00. I sent Harry Goldman the source. Overall the gap
system costs about 20 to 25 dollars.
So, where does this lead? First we get complete control of the most
important part of the TC..the gap. With a repeatable gap system I have
been able to concentrate on the relationship between the five elements of
the TC, ie. the neon, the cap, the primary, the secondary and the
terminal capacity. I am of the opinion that for a given driver
transformer, there should be an ideal primary, secondary, cap and
terminal capacitor. We all know that we can make virtually any secondary
work, but......do we know we are getting the most out? I have personally
progressed from about 12" discharges to 48" to 54" discharges using a
15kv 120ma neon. I do not know the limit but I do know I am not getting
all of the neon power into the TC yet. Thus my need for help on
determining how much power is actually being transferred and with that
known, the next step should become apparent.
I have rambled on quite a bit and I would certainly appreciate your views
and the views of everyone in the group. Who knows...the results of my
playing around may have some application to firing those pigs that you
For bigger and bigger sparks and less smoke
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