Re: Rotary Spark Gap Design

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Black Moon" <black_moons@xxxxxxxxxxx>

Heh, you really need to research tesla coil design..
At 440v, you'd need a giant non polarized cap, expensive and hard to get, 
and hence you'd have no primary turns.
also, tesla coils don't operate on 'dc' themselfs. theres not even any need 
to rectify if your BPS (bangs per second) is 120 or over. they operate by 
chargeing a cap from a high Z source, then the sparkgap breaks down, and 
the whole cap and primary form a LC osilator that rings.
As stated below, you need high voltage. And we know your making a classic 
hv tesla coil, as tube and SSTC coils don't use sparkgaps.
And as stated by many people, wood is bad, you want plastic, perferabley 
thick strong uncolored plastic :P And you have to balanace it extreamly well.

> 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.
> >
> >
> >