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Neons and Sync Gaps
From: Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: Wednesday, September 24, 1997 3:32 PM
To: tesla-at-pupman-dot-com
Subject: Re: Neons and Sync Gaps
Hi John,
> From: FutureT-at-aol-dot-com[SMTP:FutureT-at-aol-dot-com]
> Sent: Wednesday, September 24, 1997 3:11 AM
> To: tesla-at-pupman-dot-com
> Subject: Re: Neons and Sync Gaps
>
> In a message dated 97-09-23 19:41:51 EDT, you write:
>
> <<
> > Might be time for the scope again. I've never seen it quench with
> > energy still in the primary. I wasn't using airblast as such - just a
> > gentle breeeze from a fan. Can your rotary quench first notch with
> > no output streamer? Wherever that energy is coming from, it doesn't
> > need to be a great deal to seriously overvolt the neon. It was very
> > low judging by the safety gap discharge. 1/2 inch "safety" gap
> > setting is no real safety at all.
>
> > Still tryin' to crack it I guess,
> > Malcolm
> > >>
>
> Malcolm,
>
> My TC requires full power output streamers to get 1st notch quench,
> even at half power I get 6th notch quench with the 2 series gap series
> rotary (not sure about the 8 gap series rotary at half power). With no
> output streamers, I never get 1st notch quench. I agree, any gap is
> unlikely to quench when there's any energy in the primary.
>
> Was your 1/2" safety gap 1/2" total, or 1/2" on both sides of trannie?
> I assumed you meant 1/2" total.
>
> John Freau
It was 1/2" total. Total main gap setting was 1/4". There might be a
rule of thumb emerging out of this as you can see. The safety gap
wouldn't fire beyond this setting. I would therefore expect that a
1/2" main gap would cause a safety gap to fire up to 1" or so. That
being so, it becomes clear that if a transformer is designed and
wound to spec, the secondary should be able to withstand 2x o/c
output voltage impressed as a fast risetime impulse across its
secondary. For real safety, I'd say a 3x rating would be something of
a guarantee. It is becoming very clear why the neons are inherently
weak in Tesla service as Richard Hull eloquently puts it.
BTW, I'm part way through unpotting my unit. I will persist to
the death and am going to modify the core (which appears to be E-I
lams on my unit) to build a robust 2kVA unit. I am planning to cut
the centre leg of the E's and make bobbins to fit at opposite ends
of the core a la:
--------------------------------------
| |
| ------------------------- |
----------------- --------------------
| | | |
| | | |
----------------- --------------------
| ------------------------- |
| |
---------------------------------------
This gives a huge winding window and would allow for the insertion of
shunts if so desired. BTW, the secondary wire in the original is not
as small as I thought but based on what I've seen so far, the enamel
they've used is no match for modern polythemaleze. I am not surprised
it failed given what I know now. They sure didn't build them for
Tesla service.
BTW, the unpotting is a horribly messy business. However, I'm
indebted to Richard Quick for the information he provided which gave
me the inspiration I needed.
Lastly, the gap distances and known o/c peak output voltage of
the transformer suggests the 35kV/inch rule is a very useful guide
for these sorts of distances.
I am going to place a caveat on this. I regard the above guide as
true for sharpened wire ends. However, nice rounded electrodes should
have this figure doubled IMO. I think based on observation (plus
information from Glasoe and HPE) that 70kV/inch is far more realistic
for a typical gap electrode. In other words, if you static gap is set
at 1/2", you are probably firing at 30kV+ so watch those transformers.
I have Jason in mind while saying this. According to this then, my
setup was firing at around 17kV which was the o/c peak transfromer
voltage. Sorry for equivocating once again :(
Malcolm