Re: SSTC bridge driver

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

Original poster: "Shaun Epp" <scepp-at-mts-dot-net> 

David,

The snubber circuit was an addition, I left the 1kohm in place.
The ringing on my board was so bad that it fired the mosfets on and off.  To
see if you board does this, scope the output and use a light bulb as the
load.  If you see sharp spikes on the waveform then it's a problem.  The
snubbers fix this.

On another post, and where I've read elsewhere was that the leakage
inductance is the
culprit, but I twisted my three wires together before I wound them on the
core and I kept the leads short as possible to the circuit board.  I don't
think that that was the problem.  I also increased the value of the coupling
capacitor from the driver chips to the gate transformer.  I went from 0.1 uF
to 1.0 uF polypropylene.  I did this after playing with the snubbers, It
makes the waveform look more square and clean.

Shaun

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, February 01, 2004 7:54 AM
Subject: RE: SSTC bridge driver


 > Original poster: "David Trimmell" <humanb-at-chaoticuniverse-dot-com>
 >
 >
 > Shaun, so you replaced R5-8 (1K) (PlasmaSonic II) with series 51K and
 > 1nF cap? Or was this in addition to?
 >
 > Thanks,
 >
 > David Trimmell
 >
 >
 > From: Tesla list [mailto:tesla-at-pupman-dot-com]
 > Sent: Saturday, January 31, 2004 4:57 PM
 > To: tesla-at-pupman-dot-com
 > Subject: Re: SSTC bridge driver
 >
 > Original poster: "Shaun Epp" <scepp-at-mts-dot-net>
 >
 > I've got the answer to the ringing problem.  SNUBBER circuit!  I use a
 > 51
 > ohm 1/4 watt resistor in series with a 1 nF capacitor. I put this combo
 > across the gate transformer outputs and it gives a good response.   On
 > my
 > plasmasonic board I'm running at 240 khz and the ringing was about
 > 13Mhz.
 >
 > I hope this helps,
 >
 > Shaun Epp
 >
 >  >>>Snip<<<<<<<<<<
 >