SSTC Interrupter problems
Zum Beispiel, Sun Jul 15 2007, 02:31PMSo here's the deal: I finally built a "real" SSTC, nothing fancy, just a halfbridge of IRFP450's driven by the usual antenna feedback system. Power is fullwave rectified unfiltered 230V mains.
The coils resonant frequency is around 340kHz and I have a start-up oscillator running at 160kHz. The coil works just great. I get hot streamers about 20cm in lengh, and I'm drawing about 3A from mains. Still room for improvement, though
Now the problem: I want to use an interrupter, so I can get other effects than just the CW brush discharge. I made a controller that goes from 1 to 200Hz and 0 to 100% duty, but when I have it hooked up on the UCC3732* chips enable pins, the coil just won't start to oscillate! I scoped the gates with the interrupter on (with no power on the bridge, of course) and the drive signal is fine. The damn thing won't even oscillate when I have the interrupter turned to 100% duty!
If I poke the break out point with a discharge stick I get a small spark, but that's probably cause the coil is being driven by the start up osc.
So, help?
Re: SSTC Interrupter problems
thedatastream, Sun Jul 15 2007, 03:18PM
Perhaps changing your start up oscillator frequency nearer to the fres of the coil would help. Then you will get a more reliable startup when the interrupter turns on.
I can also recommend Steve's PLL Circuit - I used this in my small SSTC and interrupter with no problems. It has the advantage of it's own oscilator in circuit so removing the need for an external one.
thedatastream, Sun Jul 15 2007, 03:18PM
Perhaps changing your start up oscillator frequency nearer to the fres of the coil would help. Then you will get a more reliable startup when the interrupter turns on.
I can also recommend Steve's PLL Circuit - I used this in my small SSTC and interrupter with no problems. It has the advantage of it's own oscilator in circuit so removing the need for an external one.
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