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Re: Optimal Quench & Update
Subject:
Re: Optimal Quench & Update
Date:
Tue, 1 Apr 1997 14:23:11 -0500 (EST)
From:
FutureT-at-aol-dot-com
To:
tesla-at-pupman-dot-com
>> I set up a small 360 VA (12kV, 30ma neon) coil for quench testing.
> > Steady
>> first notch quenching was achieved at k = .11, k = .12, and at k = .18,
> > spark length was 36".
> >
> > Specs are as folllows; Primary is #12 standed pvc ins, 15 degree
> > inverted
>> cone, tapped at 33 turns (448uH). C = 0.007uF, polypropylene.
> > Secondary is
> > 6- 1/2" by 23" plastic form wound with #28 formvar, L = 108mH. Resonant
> > frequency without toroid is 130 kHz, with toroid is probably about 100
> > kHz or
>> so. Toroid is 4" by 17" aluminum dryer duct. Gap is a 120 BPS
> > synchronous
> > 12 point super-series quench rotary (the spark snakes through 12 gaps
> > during
>> each firing). There are 12 spinning and 12 stationary electrodes, all
> > electrodes are 1/8" dia. stainless steel. Motor is 3600 rpm, 1/10 HP
> > salient
> > pole design with ~7" rotor. Six of the gaps are "offset". Maximum
> > voltage applied to the Tesla coil transformer is 125 volts.
> <SNIP>
> John,
> Great experiment! In order to hit k=.22 without self-destructing your
>secondary, you may need to use a relatively heavy overcoating of some
>type (Behr or similar). Also, its very interesting that you were seeing
> near-linear ringdown on the secondary - this may indicate that the power
> dissipation properties of heavily-conducting secondary streamers are
>similar to that observed in the primary circuit arc...
> Safe coilin' to you, John!
>-- Bert --
> <SNIP>
>> John Freau
Bert, All,
Yes, I was surprised (but glad) to see such a rapid ringdown, seemed to
show
good power transfer, maybe I just happened upon a good impedance match.
I did a few more tests which I'll describe:
First I went back and found the the magic k points that I had missed
before,
and as expected, I was able to obtain first notch quench at these other
k
values. Next, I jumpered across 6 of the 12 gaps to test the system
under
"poor" quenching conditions. This caused quenching on the 3rd notch,
and
sparks were about 20 % weaker, but coil ran poorly and unsteadily.
Back to normal operation; one time at k = .15, with input voltage at 130
volts, I thought I saw the spark hit 42", but this happened only one
time.
In general, spark is longer at k = .12 because only one streamer is
formed,
the spark regularly reaches 38" with variac set at 130 volts.
Next, I tried to achieve first notch quenching at k = .22, but the
attempt
failed, and 2nd notch quenching was obtained, along with racing sparks
which
caused some damage to the secondary. Perhaps a slightly larger toroid
would
help the quenching by increasing the loading, and might also cause only
one
(longer) streamer to be formed. I have also noticed that quenching is
easier
with multiple streamers than with one long one. At k = .22, the system
is a
real "Behr"! : )
Towards optimal coiling,
John Freau