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Re: sparks



   Is there not a relationship between spark length--or at least characterics,
and operating frequency?
(Have the schematic John. Thanks. Working on 833A sockets.)
Dave Hartwick

Tesla List wrote:

> Original Poster: FutureT-at-aol-dot-com
>
> In a message dated 99-02-08 06:05:50 EST, you write:
>
> << My question is this: I've read many previous posts about people getting
> > 50"-60" sparks and more from a 6" secondary. The most I've been able to
> > obtain is about 36"-40" my specs are below:
>
> > 15K/60 ma NST
> > 16 turns of 1/4" copper primary spaced 3/8"
> > 6.5" X 28" secondary wrapped with 20awg
> > 4" X 20" toroid
> > 3 rolled poly caps in series = .01 uF
> > RQ design circular static gap -6"pvc/1-1/4"copper tubes with muffin fan
>
> > Did I blow it using 20awg? Is there something I can do to improve spark
> > length? Or is this the best I can expect from 60ma? Any suggestions from
> > the more skilled coilers out there is appreciated.
>
> > Bob V
>   >>
>
> Bob,
>
> The biggest contributor to spark length is input power.  The size of
> the secondary has a much more modest effect.  However the inductance
> ratio between the primary and secondary does seem to be relatively
> important.  The spark length you are obtaining is about normal for that
> size NST.  If you are getting multiple streamers from your toroid, that
> will reduce their length somewhat.  But folks often prefer multiple
> streamers...it looks more exciting.  (A larger toroid will produce
> fewer streamers).   If you widen the spark gap spacing
> you might get longer sparks, but you'll probably destroy the NST.  It's
> best to keep the spark gap spacing reasonable and accept the present
> performance.
>
> If you add another identical NST in parallel, and double your capacitor
> size, and use a larger toroid, you should get about 40% longer sparks,
> if your gap can still quench OK, at the higher power level.
>
> I use a low break rate (120bps) with a synchronous rotary gap, and
> a larger (6" by 26") toroid, to obtain 64" sparks using a 15kV, 60ma
> NST.  The secondary is 4 1/4" by 24", wound with #28 wire.  This
> secondary is running on the edge of breakdown however.  The
> cap is .014uF.  In an earlier experiment, I used a static gap and
> obtained only 48".  The main reason for using a large secondary
> on a powerful TC, is to prevent voltage breakdown, and to reduce
> toroid to primary strikes.
>
> John Freau