RE: Self-Resonant SSTC topologies

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

Original poster: "David Trimmell" <humanb-at-chaoticuniverse-dot-com> 

Thanks for the suggestions. I think it'll be some time before I get
burned out on SSTC's, but you never know ;-)

I wound my current transformer on a core of type 77 material with 60
turns #24 magnet wire and used one turn of the RF ground lead. After
trying this I am done with antennas, as this works wonderfully!

I see that Dan M has the idea of trying the Magnifier configuration, now
that should be quite interesting. Using the RF ground current
transformer for self resonance should work nicely. Once I clear some
space I an going to try this with my small driver.

Regards,

David Trimmell

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Saturday, May 15, 2004 8:23 PM
To: tesla-at-pupman-dot-com
Subject: Re: Self-Resonant SSTC topologies

Original poster: "K. C. Herrick" <kchdlh-at-juno-dot-com>

David-

Before I became "burned out" on SSTCs, I successfully used as feedback a
signal derived from the return end of the secondary.  Just feed that
through a low resistance (10-50 ohms perhaps) to ground.  Couple the
(sine wave) voltage across that resistance through 1K ohms or so to a
pair of back-to-back diodes, also to ground.  Take the voltage across
those diodes, amplify it, and use it to drive the MOSFETs or IGBTs.

You may need to connect a capacitor across the low resistance in order
to
shift the phase appropriately.  Also, of course, you must be sure that
the amplified signal is in phase and not 180 degrees out, for driving
the
transistors.

This technique causes the system always to be in tune with the
secondary's Fr.  Also, it's self-starting, with sufficient amplification
to allow noise to do that job.  I used it with an untuned primary; with
a
tuned primary...I don't know.

Good luck.  Be sure to provide a big enough container for receiving your
burned-out transistors.  I'd suggest a 55 gal. oil drum.

Ken Herrick
Oakland, CA USA

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