RE: SSTC bridge driver

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

Original poster: "David Trimmell" <humanb-at-chaoticuniverse-dot-com> 

Yes, my typo. The harmonics blocked wouldn't help ;-) I will add that I
think snubber's may be a good idea, I have had good results with Dan's
design as is. I did have an initial failure in the beginning (still not
absolutely sure why...), but after repairs and FET replacement things
have been very good. Also, I have found that the tda1524a IC makes for a
pretty good preamp with tone control for feeding audio from a line
source like a CD "walkman". Hopefully this post will make it through ;-)

Regards,

David Trimmell

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Tuesday, February 03, 2004 12:03 PM
To: tesla-at-pupman-dot-com
Subject: Re: SSTC bridge driver

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

Oops, I just noticed that someone replied back and said the snubber was
51K
in series with 1 nF.  NO!, that won't do anything!

Use 51 ohms in series with 1 nF for the snubbers.

Shaun


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Monday, February 02, 2004 8:56 AM
Subject: RE: SSTC bridge driver


  > Original poster: "David Trimmell" <humanb-at-chaoticuniverse-dot-com>
  >
  > Interesting. I wonder if this would have helped some situations I
have
  > seen leading to blown FETs. Dan's tests and Sims are great, but while
  > under audio mod you can get some nasties from Fr instability (how can
  > you be right on tune with loud music?). The feedback control may lag?
I
  > personally can't see what's wrong with a added snubber circuit, yes
it
  > does increase complexity and component count, but...
  >
  > Thanks,
  >
  > David Trimmell
  >
  >
  >
  > -----Original Message-----
  > From: Tesla list [mailto:tesla-at-pupman-dot-com]
  > Sent: Sunday, February 01, 2004 4:51 PM
  > To: tesla-at-pupman-dot-com
  > Subject: Re: SSTC bridge driver
  >
  > 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<<<<<<<<<<
  >   >
  >