From: Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: Tuesday, September 23, 1997 2:49 PM
To: Tesla List
Subject: Re: Primary Qs
You're observing M on a learning curve here...
> From: FutureT-at-aol-dot-com[SMTP:FutureT-at-aol-dot-com]
> Sent: Tuesday, September 23, 1997 4:53 AM
> To: tesla-at-pupman-dot-com
> Subject: Re: Primary Qs
> In a message dated 97-09-22 22:31:39 EDT, you write:
> << There is no doubt my neon was killed by a "kickback". For
> > months/years I have been wondering how a voltage higher than that
> > generated by the transformer could appear across the transformer
> > terminals (resonant charging and wide-set gaps aside). The answer
> > lies in the impedance of the transformer at the RF frequencies. If
> > some energy still remains in the sec of the coil after the gap has
> > gone out, it is coupled back to a series-tuned primary which is now
> > in series with an ultra high impedance presented by the transformer.
> > My filter setup prevents the transformer ringing with the filter caps
> > but in the process, I have boosted the impedance across the
> > transformer terminals. I should have used filter caps big enough to
> > limit the rise of a moderate amount of energy that could be fed back
> > while at the same time ensuring an unfavourable ring frequency with
> > the transformer. The only simple answer I have right now is bigger
> > filter caps. Back to the lab.
> > :(
> > Malcolm
> Malcolm, all,
> I have seen horrific kickback in both pulsed spark-gap and pulsed
> tube type coils. Static gaps which fire intermittently, or quench
> strangely may be causing a similar effect. Sub-optimal spark-
> loading of the secondary/toroid may also allow the secondary to
> ring longer than desired, and couple more energy into the high
> impedance series neon circuit as you said. In my TC, I obtain
> rather fast resonator ring down...less time for the neon tar to
> If it's kickback that's doing the damage, then maybe resonant
> charging is relatively completely safe. Have you estimated the
> peak voltages of the kickback in your system?
About 20kV+ judging by the "safety" gap setting. It was as if a small
amount of energy suddenly ran into a brick wall. I used to think that
resonant charging was the problem until I saw this. I still think
overvolting is a problem but letting resonant charging take one up to
peak o/c transformer voltage would seem to be just fine.
> Would simple 3k ohm resistors in series with the neon output
> leads reduce the RF enough, esp. with some bypass caps to
I had my much loved "filter" board in the line when all this happened.
> Just tossing out some thoughts here,
Thanks. This one deserves to be cracked. It is a problem for
everybody. I'll do more work on it when I get another neon.