RE: MOT w/doubler question

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "David Dean by way of Terry Fritz <twftesla-at-uswest-dot-net>" <deano-at-corridor-dot-net>

Hi Pete,

I have given a bit (not much though) of thought to this. My instinct would
be that it may reduce the current some but would probably reduce the voltage
more. Instincts can be wrong however. I will try to find time this weekend
to do some modeling with that circuit and a TC in Microsim. The key word
here is try, as so far this week I have hardly been able to read some of my
email, let alone respond to anything, trying right now to catch up on five
days worth.

You are wanting to use a static gap, correct?

If so, then I would suggest using resistive or inductive ballast in series
with the primaries of the MOTs to limit the current rather than trying to do
it on the secondary side. With the level shifter circuit that should work
because the caps are used to cause a DC offset in the AC voltage so that the
negative peak of the positive supply hits zero as the positive peak of the
negative going supply hits zero so the supply will behave like an AC supply
rather than a DC one. While there is no true "zero crossing", the fact
remains that the mechanism is in place to allow quenching, that is the
lowering of voltage across the gap to below that required to sustain an arc.
If on the other hand you were to have a true DC supply with filter
capacitors, they (the caps) will store energy which will be drained when the
gap fires. In that case the filter caps would have to be isolated from the
spark gap / tank circuit by either a resistor, a charging choke, or a
special rotary gap design. If not, then the gap will continue to conduct
until all the energy is removed from the storage capacitors thus defeating
the purpose of having a DC supply in the first place.

later
deano

> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Tuesday, January 23, 2001 9:18 AM
> To: tesla-at-pupman-dot-com
> Subject: RE: MOT w/doubler question
>
>
> Original poster: "Peter Lawrence by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <Peter.Lawrence-at-Eng.Sun-dot-com>
>
>
> Deano,
>       can I current-limit my voltage doubler by using a smaller cap?
> Stands to reason, but I think I have to ask. As it came from the microwave
> the circuit has a 0.65uF cap, thats 67 times the size of my 9.6nF
> NST-Res-sized tank cap, enough for a lot of gap-arcing energy.
>
> -Pete.
>
> > Hi Pete,
>
> > It looks as though you have the hang of it. For more information on the
> > subject, go to www.corridor-dot-net/deano . There you will find a
> file called
> > diode.zip that has the basic theory on DC power supplies. This
> level shifter
> > circuit works quite well with a SRSG running at 60 BPS. With a
> static gap
> > you will probably need more current limiting than provided by a
> T.F. style
> > filter circuit. The current will still tend to be rather high
> making the gap
> > hard to quench.
>
> > later
> > deano
>
>
>