Re: Thyristors and TCs

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

Original poster: "David Sharpe by way of Terry Fritz <twftesla-at-qwest-dot-net>" <sccr4us-at-erols-dot-com>

Ben, John

In short, yes it can be done, however, you better have deep pockets.
Terry was infact was working on an optically isolated IGBT solid state
spark gap (SSSG), cost for power semiconductors alone was in excess
of  $2k.  << Terry jump in with info on this work.>>    :^)

http://hot-streamer-dot-com/TeslaCoils/MyCoils/SolidStateCoil/

There are commercial parts (IGBT's to 6.9kV, SCR/Thryistors to
15kV), but they must be (1) optically isolated by fiber optics, (2) control
power supplied by small PT's capable of holding off applied HV,
(3) should be inverse parallel for full wave control, (4) very high speed
control electronics (<<1usec switching speeds) in a very high ambient
electrical noise environment, requires extreme care in circuit layout,
shielding, construction and design techniques, and grounding.
These points all add up to very esoteric (read expensive)
electronics.  However, I can remember about 7-8 years ago that there
were NO commerical electronics to perform this task at ANY price
(what the military/federal agencies/national labs had at that time is
anyone's guess).

My bet is someone will successfully build and operate a SSSG
replacement within the next 10 years when parts become more
available, surplus industrial power electronics becomes available at
scrap yards, and power electronics and controls become more
integrated, user friendly and reasonable in first cost.  The
cost will still be out of reach for probably 75% of us though.

A static spark gap can be built for <<$20, a RSG even with machine
shop time can be fabricated for <$1k.  A SSSG today would be at
least $5-10K or more, depending on HV input, and power
processing capacity, control requirements, etc. etc.

Regards
Dave Sharpe, TCBOR
Chesterfield, Va. USA

Tesla list wrote:

> Original poster: "Ben McMillen by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <spoonman534-at-yahoo-dot-com>
>
> Hi all,
>    I also had a simial question but it appears that John beat me to it..
;) Is
> this at all possible? I remember a thread awhile back that discussed using
> MOV's as spark gaps, but the eventual conculstion was that they were
ultimately
> too slow.. Does the same apply here? I think these SCR's will handle alot of
> current, but in order to hold off the voltage they'd have to be seriesed and
> possibly paralled for more current.. while a single one is quite fast,
putting
> several in a network would make them slower.. at least I think.. Anyone have
> any ideas?
>
> Coiling in Pittsburgh
> Ben McMillen
>
>   Tesla list <tesla-at-pupman-dot-com>
> >
> >  wrote:
> > Original poster: "by way of Terry Fritz "
> >
> > Hi guys! I have in my possession 12 Westcode thyristors.The bummer is i
don't
> > have the "stats" on them.Westcode hasn't answered my mail yet.These are 3/4
> > hockey puck size,hefty little guys.They came out of some monster power
> > supplies.Has any one thought of making a solid-state gap with one (or
more )
> > of these?Is it possible?
> >
> > john in nyc
> >
> >
> >
> >
> >
> >
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