Re: DC powered Coil single phase 14.4KV 5KVA pig DCPTC ?-)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: tesla@xxxxxxxxxxxxxxxxxxx

This has been my approach. I like the idea of being able to fire the gap
anytime I want, and not having to wait around for the 60Hz cycles to be
lined up just right. Proof that this is a big deal is that people use
synchronous spark gaps.

I don't see the point to ballasting with a DC power supply either. The
tank circuit of a tesla coil can be isolated from the power supply with
extra contacts on a sparp gap. With this, there's no dead shorts across
the power supply and no need to try to battle this. I've done this with an
AC coil, but without the rectification and filtering of the power to the
coil, there's really no point to trying to use variable break rates on
your spark gap.

I kept blowing out diodes, even with two 15kV 30mA transformers. There's
apparently lots of ugly ringing that destroys them pretty fast.

I've run out of space to work on my DC coil for the time being. I'v got
some compensated-like recitifier stacks and a tube of fast, and fast
avalanche rectifiers to try out. There will be lots of blue smoke fun when
I clear some space to work in again.

KEN

> Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>
>
> Greeting All,
>
> I am considering building a full wave rectified and filtered DC supply to
> enjoy the perceived  luxury of have a variable speed RSG. Materials on
> hand:
> 14.4KV @ 5KVA Pig, 250 amp arc welder ballast, Powerstat (1256d (0-280)
> 7500
> VA max) for power up. Proposed is to wire the Powerstat between the mains
> and the series ballast. I purchased (24) stackable 7500v 1.4amp diodes
> from
> alltr? planning on stacking six per leg for the bridge. I plan to float
> the
> Center tap and ground the transformer. I seem to remember varying opinions
> on whether this should be done to Mains or RF ground. I have a typical 8?
> X
> 36? coil and numerous pulse capacitors but my present focus is on the
> Power
> Supply. I don?t plan on ever running past 500ma out. Open for discussion
> are
> filter cokes, charging inductors, and of much concern Protection of the
> Bridge or it?s robustness for that matter.
>
> I?m a signal level guy? For starters what is an appropriate filter
> capacitor
> and suggested sources and should it be preceded by a filter choke? It
> would
> seem that multiple smaller Caps would be safer then one big boomer. Please
> forward to the list if the thread would be of interest to the group.
>
> Thanks Much,
> Jim Mora
> Fillmore School District, Retired
> Ojai, Ca.
>
>
>