Experements with an SSTC

I decided to have a play with an SSTC, Having not prepaired anything or ordered anything, it had to be from parts I had lying around.

So, Taking a pre wound secondary (1.3" diameter 800ish turns), a spare 2" topload ( wodden ball covered in alu foil) an old half bridge that I never used in anything (2x irp460 and GDT) ,my last IXY mosfet driver ic , a Transformer from an old VCR (with all of its outputs seriesed to give me 140V at about 300mA smoothed with a 400uf 400V cap.), primary of two turns of 4mm^2 around a 2" cardboard tube and I made a self resonant digital driver using the circuit from millie tess (bread boarded).

Powered it up and "pif!" , sparks.. total build time 2 Hours...

Mosfets get a little hot, I must add a heat sink..

The first light was not too impressive. I had the interrupter at about 1khz and 50% mark space.
After noticing that there was a much bigger spark on turn on, I decided that the PSU was not supplying enough current.
So I changed the interrupter to about 8Hz at 1:10 mark space, and got the result shown. 2" sparks.

I played around with the coupling, and moved the primary coil to the top of the cardboard roll. givein an increase to the spark length (3"), and making them much more VTTC like..

I had a thought, and shortened the breakout point to about 1/2", this really give me VTTC like sparks.. now 3.5" long.

Next A full bridge and/or 240V... Need a heat sink...

My order came for the IXY Drivers, so I now have a full bridge driving the GDT, giving me 10-12V of drive to the mosfets.

240V in, Worked for a while and then took out both mosfets.. Probably due to:-
1. I only had a two turn primary ( well youve got to push it a little..) so back to a 3T primary.
2. When the oscilator was starting up it started at about 5Mhz and only gave 5V drive via the GDT at this frequency, I changed the cap on the start up Osc, and It's run ok since.

6" Sparks !! (the coil is only 5" tall). I need a strike rail before I get any bigger ones!!!

I've had to reduce the coupling, as I was getting strikes to the primary, and this has made the sparkes more bushy, maybe its this that gives VTTCs their sword like outputs..

Next A full bridge or a resonant primary,
Oh yes... and a heat sink...

A quick play replacing the breakout with a candle.

A cool bright white plasma, with a few streamers..