Re: SSTC

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

Original poster: "Jolyon Vater Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>

How about replacing the spark gap with a chain of zener diodes/ does this
work?

Jolyon
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, December 19, 2002 7:42 PM
Subject: Re: SSTC


 > Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
 >
 > Hi Herwig,
 >
 > At 11:31 AM 12/18/2002 +0100, you wrote:
 >
 > >Hi SSTC coilers,
 > >
 > >Spark gaps are said to cause up to 1/3 of a TC system's losses. In
 > >order to reduce these and as NSTs are rare in this part of the world,
 > >I'm planning on substituting the static spark gap of my small 2"
 > >system with silicon. Of course the system needs to be redesigned.
 > >
 > >1. Does John's formula "input power vs streamer length" still hold or
 > >could I expect a distinct improvement?
 >
 > Assuming the SSgap is very good, you could almost expect 50% more power to
 > the streamers so maybe the equation would be:
 >
 > L = 1.7 x SQRT (input power x 1.5)
 >
 > Hard to say for sure since it depends on a number of things, but it should
 > certainly do much better than a conventional gap.
 >
 >
 > >2. Are there any drawbacks (besides of $$ of course)?
 >
 > It is tricky trying not to blow up the silicon.  A nice scope and
 > current/HVvoltage probes really help.  One maybe big problem is that a
 > small coil will run at pretty high frequency so the losses may be higher
 > than say my 36.5kHz OLTC.
 >
 > John Freau mentioned "So far there has been no efficiency improvement if I
 > remember correctly. "
 >
 > The gap itself is very efficient.  It can switch 3 joules at 120BPS (2500
 > amps!) while barley getting warm.  My problem was much more silly
 > convention secondary low Q losses since I have so much small wire on a
 > lossy cardboard form.  The gap part works great!!  I also loose some power
 > having to switch like 2500 amps, but my stupid secondary is most of the
 > problem.  Should have been plastic...  However, as time goes on and it
gets
 > drier and drier, the Q is constantly getting significantly better ;-))
 >
 > I still have not manage to run it at really full power (240VAC
 > in)...  Hopefully, some other projects will get finished up soon and I can
 > get back to it ;-))
 >
 >
 > >3. Searching the archives I've found that half wave rectification is
 > >used often. Wouldn't full wave rectification result in a higher
 > >throughput? Could one of the experts please enlighten me?
 >
 > Half wave seem to work very well if the input is DC.  AC switching may not
 > really work better since a fixed diode for the reverse direction is pretty
 > efficient and simple.
 >
 >
 > >Cheers
 > >
 > >Herwig
 > >---------------------------------------
 > >Greed is the root of all evil!
 > >---------------------------------------
 >
 >
 >
 >