Re: Opt. Qnch. update--1st notch

To: tesla-at-poodle.pupman-dot-com
Subject: Re: Opt. Qnch. update--1st notch
From: Tesla List <tesla-at-stic-dot-net>
Date: Mon, 14 Apr 1997 00:13:40 -0500
Approved: tesla-at-stic-dot-net
Subject: 
        Re: Opt. Qnch. update--1st notch
  Date: 
        Sun, 13 Apr 1997 17:31:13 -0400 (EDT)
  From: 
        FutureT-at-aol-dot-com
    To: 
        tesla-at-pupman-dot-com


> Hi John,
>           I have to thank you so much for the excellent experiments 
> you are doing. This latest post really caught my eye and in 
> particular, the last bit:
 
><big snip>
>> Adjusted sync-gap phase for more power input, now neon trans draws 11A
> > at 240
> > V, (2640 VA), multiple streamers are produced, and sparks reach 65"+.  I
> > tried adding external ballast to this 15kV, 60ma neon trans, but it
>> still
> > draws a lot of power, and sparks are greatly weakened.  In general,
 >> quenching
 >> occurs on the second notch, but moves to the third notch when a
streamer
> > strikes a ground.
 
>This all shows evidence that it takes a discharge to affect quenching 
> - i.e. the system is coupled *during* secondary discharges. More 
> interesting though is the shift of the quench when the discharge 
> becomes heavy. This is the first evidence I've seen outside my own 
> experiments that the lowered terminating impedance reflects back to 
> the primary as a higher feed impedance. I am extremely interested in 
> these results. I'll stick my neck out and hazard a guess that an even 
> greater primary surge impedance at this k would improve that quench
> (or a lower k for the same primary).
 
> Please keep us posted.
 
> Regards,
> Malcolm
  >>

Hi Malcolm, All,

Thanks (Malcolm) for the nice comments and interest in my work.  I did a
few
new experiments which lend additional support to the above:

First, I moved my scope further from the TC, and I'm having less
problems
with triggering.   I observed the quenching more carefully, and it now
appears that I am getting steady 1st notch quenching, (no changes to
system,
so it was probably quenching on first notch on the last test also).  If
the
spark hits a ground, the quench moves to the second notch.  I must admit
that
I was surprised by this effect since I thought that the heavy loading of
a
ground hit would help to improve the quench.  I was not familiar with
the
high reflected impedance effect that you mentioned, I'd be interested to
hear
more about this.   The calculated frequency of the primary tank is about
74kHz, so the ~125uS beat period (visible during 2nd notch quenching), 
and
the 175uS free ringdown (after the quench -- 1st notch quenching) seems
about
right. (measurements may have been at less than full power).  Seems like
a
loaded Q of about 18.

Next, I turned down the input variac to about 120V (instead of 130),
sparks
shorten to about 42", still quenches on 1st notch and only one streamer
is
now formed.

Turned down variac to about 110V, sparks shortened to about 28", quench
alternates between 1st and 2nd notch in a random fashion, probably due
to
insufficient streamer loading.  After about 10 seconds, the spark moved
to
the third notch (and stayed there) and the audible pitch of the TC
increased.
 Probably the gaps were heating up because not enough energy was being
drawn
out by the steamers, also the gap was probably only firing at 60 BPS at
first, then as the gaps got hot, they fired at a lower voltage, thus the
TC
was able to run at 120BPS,  (upon shut-down, gaps were warmer than usual
which supports the above scenario).

Turned down variac to about 105V, sparks shortened to about a 22" spark,
quench varied, 2nd or 3rd notch.

Turned down variac to about 100V, sparks shortened to about an 18"
spark,
quenched on the 4th notch.

I suspect that I may have enough "leeway" in the system to increase my
coupling and maintain 1st notch quenching.  That will be the next test. 
If
my quench fails at a certain k value, then I could increase my primary
surge
impedance as you (Malcolm) suggested, but I'd probably have to rebuild
the
primary and secondary if I want to keep my cap size constant. 
Unfortunately,
I don't have the room to install a giant toroid and crank up the power
to see
what happens quenchwise. 

BTW, in my earlier experiments using the 360VA neon trans, my spark gap
electrodes were narrower than 1/8" at their tips.  Now I'm using
electrodes
that are at least 1/8" at the tips.  So I have no way of knowing if the
improved quenching I'm seeing now is due to the gap improvement, or to
greater spark and toroid loading at this higher power level.  I'll have
to go
back to the 360VA set-up to do a true comparison.

Towards optimal coiling,

John Freau