Re: Self-Resonant SSTC topologies -Morining after.

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

Original poster: humanb-at-chaoticuniverse-dot-com 

Well I messed with my lashup DRSSTC till I blew a IGBT.
I added a larger topload, but failed to account for the
need to adjust the tank C, DUH! Overall I am very
happy. I definitely will be getting some refrigerator
tubing, as the #10 wire gets hot. I am very far from
anything even remotely efficient, as I was pegging my
15 amp panel meter with only 80-100V into filter. But
these sparks are some gnarly nasty suckers! Before
killing the IGBT I was getting 24"+ sparks to free air,
would suspect that I'd get longer to a ground target
(just guessing). So I will rebuild this weekend with a
"calculated" tank (not just guessing ;-)), and clean up
the wiring (maybe actually solder those caps
together!). I will draw up a schematic with component
values as soon as possible, but basic setup is as
follows:

Half-Bridge design from Dan M:
http://www.easternvoltageresearch-dot-com/datasheets/sc2045_sheet1.pdf
But I am only using 1.5 ohm gate resistance (should I
increase this?). Also, I am using two 1.5KE180CA in
series across each IGBT (to clamp at 360V). Two
HGT1N30N60A4D's that I consider expendable ;-P (will
use the  HGT1N40N60A4D's when I get the design down).

Secondary with topload and breakout resonates at 280KHz.

Driver is on a Protoboard and is basically Steve W's
design for his miniSSTC with the interrupter circuit
using 1uF cap and two 10K pots (this needs to be better
as my pulse width is too long, I think). And finally I
have a tank cap of .05 uF. The driver is floating and
not earth grounded, and so fare with no EMI protection
it was pretty stable.
Steve's driver:
http://hot-streamer-dot-com/srward16/MiniSSTC/miniSSTCsch3.JPG

Short Windows Media video (860K):
http://209.210.231.220/webdoc2.htg/SSTC/Pictures/Self_res_proto1/DRSSTC1.wmv

Regards,

David Trimmell


On Thu, 13 May 2004 16:20:39 -0600, "Tesla list" wrote:

 >
 > 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