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Re: Spark gap varients




From: 	Peter Electric[SMTP:elekessy-at-macquarie.matra-dot-com.au]
Reply To: 	elekessy-at-macquarie.matra-dot-com.au
Sent: 	Friday, November 07, 1997 2:26 AM
To: 	Tesla List
Subject: 	Re: Spark gap varients

After having tried all of them on my 6" 15KV 60Ma coil, here are my
thoughts on gaps.

Unquenched static gaps are crap! - 12" spark or less.
Quenched multiple static gaps using a muffin fan (ala Richard quick) are
OK - 28" or so
Forced air quenched single gap (compressor at 20psi or Vacuum motor) is
excellent - around 38"
Synchronous rotary gap, 100 PPS with 4 gaps total is the best - 42" so
far.

Details of my forced air quench static are - two 3/4" rods with flat
faces mounted in a 6" drain pipe with forced air blown through. Air can
be further directed using a plastic funnel. Gap set at 5/8". These are
the easiest gap to build for the best performance IMO.

Details of sync rotary are - 1/10 HP modified motor with 6" phenolic
disk (like 1/2" thick circuit board). Don't use a low melting point
plastic for the rotor as the electrodes can get very hot and launch
themselves! I have four fixed and two rotating electrodes at 3000 RPM
giving 100PPS. Electrodes are 3/8" by 2" with flat faces. Gaps are set
very close, 5/1000" each. With these gaps the phasing is very critical
and must be reset for each Cap/Transformer combination. It has to be set
right within about 10 degrees to work well.

My two pesos worth,

Cheers,  Peter E.


Tesla List wrote:

> From:   Mike Harrison[SMTP:wwl-at-netcomuk.co.uk]
> Reply To:       wwl-at-netcomuk.co.uk
> Sent:   Wednesday, November 05, 1997 10:29 AM
> To:     Tesla List
> Subject:        Spark gap varients
>
> Although there's tons of info on building caps and coils on the net,
> there seems to be a lot less on gaps (maybe there's nothing to say..?)
>
> I have a few queries :
> Is there a preferred electrode shape - pointy, flat or round ?
> There are several references to using multiple gaps in series, and
> using a fixed gap in series with an RSG, and also using the 2 sides of
>
> an RSG as series gap pairs - what's the reason for multiple gaps?
>
> I'm considering designing a motor controller for an RSG which can
> phase-lock the gap to the mains cycle, with adjustable phasing - any
> comments on whether this is worth doing ?
>
> Anyone tried a linear reciprocating gap, using a solenoid ? - may be
> easier to build than a rotary, and real easy to synchronise (i.e. run
> the solenoid from AC), but would it move too slow? Perhaps you could
> use the primary current spike when the gap fires, through a second
> solenoid winding, to pull the gap apart rapidly,  to speed quenching.
> I suspect the main problem would be keeping the mass low enough to
> move fast but heavy enough not to melt!