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RE- Safety Gap


From: 	Vivian[SMTP:V.C.Watts-at-btinternet-dot-com]
Reply To: 	Vivian
Sent: 	Wednesday, November 19, 1997 11:12 AM
To: 	Tesla List
Subject: 	Re: RE- Safety Gap

>TL>Hi All,
>TL>        Having read various comments in the list I feel I should have a
>TL>safety gap to protect my neon especially as I want to open up my spark
gap.
>TL>I currently have two 3mH inductors one in each leg of the neon
transformers
>TL>secondary.  The connections goes transformer, inductor, capacitor,
primary
>TL>coil, inductor, transformer.  The spark gap is across the two inductors
>TL>which closes the capacitor - coil circuit.  Their is clearly no point
>TL>putting another gap across the spark gap so the logical place would be
>TL>directly across the neon.  However I cannot see how this helps, as any
>TL>energy to get into the neon has to come through the inductors which
already
>TL>have the gap between them, limiting the potential.
>
>TL>Can anyone explain.
>
>TL>Viv Watts UK.
>
>
>        Most anyone could explain -- if they have availed themselves
>        of some electrical knowledge in advance of coiling,  =before=
>        turning on the high-voltage.   (Pretty radical idea, huh?)
>
>                                - - - - - -
>
>        1) -- The safety gap is set  =wider=  than the main gap by
>              an RCH or two.   Thus the safety gap fires infrequently
>              if at all, if everything is cool and copacetic.
>
>              Or, to state it otherwise, the slightly wider safety
>              gap establishes an upper gap-limit for the system,
>              in case you get a bit too frisky with the main gap.
>
>        2) -- Those chokes:  Their impedance at the 60-Hz frequency
>              of the input power is rather low - maybe 5 to 10
>              ohms each.
>
>              At the frequency of the output power - say 200-KHz,
>              their impedance is around 4000-ohms each.
>
>              So - 60 Hz power from the transformer travels into
>              the system rather easily, while 200-KHz power from
>              the system does not flow so easily into the trans-
>              former.  (The way God [and Dr. Tesla] intended).
>
>              The other aspect of this: the safety gap and the
>              main gap are isolated from each other by 8000-ohms
>              in the example given, and thus not reduplicative
>              of each other.
>
>
>                                           Phyi ... (uh - you know
>                                           the litany by now!),
>
>
>                                           Robert Michaels
>                                           Detroit, USA
>


Thanks for the response Robert but I don't think you have answered my
question.  As I implied in my question I understand the action of the
inductors in protecting the transformer by their effect at 200Khz rather
than 60Hz (50 in my case).  But I am trying to understand where this extra
voltage that exceeds the neon output is coming from or more particularly,
requires extra protection.

My thoughts are that it is coming from the tank circuit (where else) but the
chokes are meant to prevent this from passing on.  When the gap is firing
what voltage is across it?  I assume it is low otherwise no energy would be
in the tank.  But when the gap ceases to conduct the primary acts as an open
ended resonator.  Hopefully this energy goes into the secondary, but if not,
would create its own emf in the primary which may cause the gap to fire
again but under its own steam.  This may account for the different sounds
the gaps make reported by some coiler's.  But even so the chokes are meant
to prevent this excess from passing through.

My chokes are 3mH and represent an impedance of around 4000 Ohms at 200Khz.
My transformer at 50Hz has an impedance of 200KOhms at 200KHz it could be
800MOhms!  Obviously its not, because of the capacitance of the neon comes
into play.  But even at 200K a protection of 8000Ohms does nothing as a
potential divider.

I can understand the inductors might ring but it seems to me that the extra
gap is basically their because the choke protection is not very good.

So from someone who has some electrical knowledge but is not afraid of
asking dumb questions  (to see if the answer is not obvious) > you say
Robert

"the slightly wider safety gap establishes an upper gap-limit for the
system,  in case you get a bit too frisky with the main gap"

Does this mean a neon cannot be operated open circuit without risk of its
insulation breaking down.  The reason I ask is, can I set a safety gap with
no load on the neon so it just doesn't fire.  That way I can open my main
gap to Max without worrying about tweaking two gaps.

Viv Watts UK.