RE: Self-Resonant SSTC topologies

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

Original poster: "Steven Ward" <srward16-at-hotmail-dot-com> 

David,

The reason my ISSTC is "Self-starting" is because when I ENABLE the 
inverting gate driver, its output goes high.  This pulses the GDT and turns 
1/2 of the IGBTs ON, this in turn starts up the oscillation.  You can 
modify most SSTCs to be self starting by using gate drivers with enable 
inputs (or you could make up a logic based scheme).  If you plan to run it 
with half-wave input you will need a staccato (like a VTTC staccato) to 
send out a high signal just *after* the zero crossing.  Im working on a 
SSTC (which uses base current feedback) that works in this manner.  So far 
i had it working great, then something happened, and while it will 
oscillate and make sparks, something isnt right with it (some odd behaviors).

So does that clear it up for you?  If not, let me know.

Steve


>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Self-Resonant SSTC topologies
>Date: Thu, 13 May 2004 16:20:39 -0600
>
>Original poster: humanb-at-chaoticuniverse-dot-com
>
>Hello, I have a couple questions to the folks who have
>used the "current feedback" methode of driving their
>SSTC's. Does this provide a "self-starting" coil? While
>using a antenna on my self res driver, I need to touch
>it in order to get the thing started (no oscillator
>IC). Schematics of the self-res ISSTC show no starter
>circuitry, so I assume this to be the case. Also, is
>phasing just a matter of changing the direction of the
>RF ground loop?
>
>I am using a half-bridge of the HGT1N30N60A4D IGBT's as
>a test bed. While running without an interruptor
>circuit I get 4-5 inch Hot CW plasma discharge (180
>VDC) pulling 5 amps (panel meter) from the AC line into
>filter. With a P-4 heatsink and fan everything runs
>stone cold, even with 5-6 minute continuous runs. But
>the coil does get nice and warm (4" wound with #28).
>Seems that #28 wire may be on the thin side, at least
>for a non-interrupted system.
>
>For a Picture:
>http://209.210.231.220/webdoc2.htg/SSTC/Pictures/Self_res_proto1/H-res_proto_lash7.jpg
>
>Future work will include adding the Interrupter
>circuit, and looking at adding the series res cap.
>Also, what about a Magnifier version? With all those
>primary to secondary flashovers, that would be a nice
>solution, no? I allways wanted to make a VTTC Magi, but
>never got around to it, hmm... Well, one step at a time!
>
>Regards,
>
>David Trimmell