Re: Rotary Spark Gap Design

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Hi,

If you reside in a fairly humid location, the wood will almost certianly
end up conducting electricity when exposed to multiple kVs. And once
a carbon "path" has been established, the electricity will promptly go
for the carbon track that has already been established which in turn
produces more heat and consequently, a bigger carbon path - a
viscious cycle that will effectly ruin any dielectric qualities that the
wood MAY have had at one time. I think some folks in the really
dry climates are able to sometimes get away with using dry wood
as a primary insulator. BUT, wood would NEVER be a good choice
for a RSG disc for reasons that have already been addressed by
others responding to this thread....

David Rieben

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Thursday, November 25, 2004 8:19 PM
Subject: Re: Rotary Spark Gap Design


> Original poster: "Harold Weiss" <hweiss@xxxxxxxxxx>
>
> Hi,
>
> I'll second that, and add that plywood glue is conductive.  I've had
tracks
> form right down the glue lines in plywood.  And that was at 3KV to ground.
>
> David E Weiss
>
>  > Original poster: "Dr. Resonance" <resonance@xxxxxxxxxx>
>  >
>  >
>  > 440 VAC won't be enough to operate your sparkgap.  You do need a NST is
> you
>  > are running a classic HV circuit and not SSTC.  The lowest reliable
>  > potential is 3 kV min.
>  >
>  > Don't use a wooden disk.  Most wood contains some moisture (3-5%) and
will
>  > not hold off the high voltages -- especially RF voltages which like to
> track
>  > across surfaces such as wood.  Or, worse, it might start smoldering
>  > internally.  Then, you shut off the lights, go to bed, and wake up to
>  > discover your shop or home on fire.  Use type CE or LE phenolic or G-10
>  > phenolic plate for the rotor.
>  >
>  > Be safe!!
>  >
>  > Dr. Resonance
>  >
>  >  >
>  >  > Dear forum members,
>  >  >
>  >  > I'm planning to build a rotary spark gap:
>  >  > 8 spinning electrodes mounted on a wooden disc,
>  >  > 2 stationary electrodes,
>  >  > brass bolts used as electrodes.
>  >  >
>  >  > I have seen in some Tesla coil designs that the AC input voltage is
>  > stepped
>  >  > up to few kilo volts
>  >  > (using NSTs/PolePigs), rectified and then fed to the tesla coil
circuit
>  >  > that is using the spark gap.
>  >  > Can I run the tesla coil without stepping up the AC input voltage ?
I'm
>  >  > planning to use
>  >  > 440VAC input, rectify it and then feed this DC voltage to the tesla
> coil
>  >  > circuit which uses a
>  >  > rotary spark gap. Any advice ?
>  >  >
>  >  > Thanks in advance,
>  >  > Rajesh.
>  >  >
>
>
>