Help in calculations
Subject: Help in calculations
From: richard.quick-at-slug-dot-org (Richard Quick)
Date: Tue, 23 Apr 1996 05:31:00 GMT
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Quoting Skip Greiner <sgreiner-at-mail.wwnet-dot-com>:
> I have been working on shunt or neon transformer driven TCs
> with some moderate success. I have spent some time reviewing
> the archieves for the numerous references in the past and they
> have been quite enlightening...
Thank you for the nice comments. I did read your recently
published paper on SRGs (synchronous rotary gaps) as applied to
neons in the _NEWS_. I was impressed. In addition, I received two
calls from people (not on-line as of yet) requesting my
comments/input on your work. Since I have never run SRGs on
neons, I referred them to you. You may receive an inquiry or
two by snail-mail on this topic.
> ... I have continued to pursue longer discharges using
> synchronous rotary gaps (srg) and now am now using a 15kv,
> 120ma neon. I have found several advantages in using a
> srg. For one thing I can actually control the voltage across
> the primary capacitor by setting the firing point in the input
> sine wave. It also appears that maximum discharge can be
> achieved by adjusting the exact firing phase of the gap(s).
> Right now I am using a srg with one firing for each half of
> the input sine wave. It is not obvious to me that I am
> achieving maximum power transfer with only one firing per
> half cycle. It is certainly possibe to add gaps or contacts to
> add another firing per each half cycle but would I gain
I have to stop and ask. I have often wondered about the
advantages/disadvantages of the work you are doing, in particular
with the neon. My question is: do you honestly think that the
performance gained using the SRG on the neon is significantly
greater than that obtainable with fast quenching static gap set
for Vmax breakdown? I am using Vmax to mean maximum voltage.
> My question(s) to the group are for help in trying to determine
> the voltage across the primary capacitor at any time "t". My
> problem is how to handle the current limiting / impedance of
> the neon and how to fit this into the classical capacitor
> charging time constant.
> For instance...If I set the first gap to fire when the voltage
> across the cap is at .707 of the peak, how long will it take
> the cap to recharge to .707 of the peak again? Will it even
> get there during the same half cycle? If I can know the time
> constants involved, it is obvious that the srg can be set up to
> fire at the right times. Also if I know the the maximum
> voltages to which I can get the cap charged, it becomes trivial
> to determine if additional fires per half cycle will gain any
> increase in power transfer.
> Why do all this? Basically I believe that bigger discharges can
> be wrung out of neons and this may be one way of doing it.
Please don't take this as criticism. It is not. I am asking you
to comment and expound on where you feel your results are taking
you, and in the process to educate me a bit more on the art of
synchronism. I am not an expert working with the equipment you
are currently using (I love that pun)...
OK, here goes:
I am a "let nature take it's course and aid it where we can" kind
of guy. Synchronous gaps seem kind of particular and rigid, which
may very well be what is required to force the last 10% possible
out of a neon. But when it comes to consistantly obtaining Vmax
firing on a spark excited Tesla tank circuit, I tend to side with
the theory that letting the tank circuit capacitor decide when
Vmax occurs is best. When the voltage peaks (meaning the cap is
fully charged and the line voltage rises due to the reduction in
current flow into the capacitor), the static gap should fire if
it is properly adjusted. The peak power should be delivered if
the gap is rapidly quenched after firing.
Having worked with very high performance static gaps (air blast
and vacuum) I would tend to think that squeezing the last 10% out
of a neon is perhaps more easily achieved using static gaps than
using SRGs. The only problem is that I have insufficent exper-
ience with SRGs (especially on neons where I have none) that I
can not say for sure one way or the other, lacking your
experimental data. How much experience do you have with high
performance static gaps in the same tank circuit?
... If all else fails... Throw another megavolt across it!
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