Re: SSTC bridge driver

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

Original poster: "gtyler" <gtyler-at-drummond-dot-org.za> 

15 Ohms would not work on most of my circuit, I usually use 68R, but
then that is at about 100Khz. If you need 240Khz that resistor will need
to be smaller that 68R to get the switching times down. Then all the
stray inductances will have to come down in proportion. Using low gate
charge fets will help a lot too.(IRFP450LC, etc) If you need a snubber
then I think you have too much leakage inductance in the drive
transformer. Too reduce this I would use a small ferrite toriod, maybe
10 or 14mm, don't use more turns than you need,(calculate it!), and wind
all windings at the same time.(use triple-insulated wire)

George

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, February 01, 2004 6:15 AM
Subject: Re: SSTC bridge driver


 > Original poster: "chris swinson" <exxos-at-cps-games.co.uk>
 >
 > Shaun,
 >
 >
 > ----- Original Message -----
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Sunday, February 01, 2004 12:57 AM
 > 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
 >
 >
 >
 > http://hot-streamer-dot-com/exxos/sstc/directdrive.htm
 >
 > I'm sure im the only one whos actually read hours or testing and
results on
 > my site!
 >
 > Chris
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >  > 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
 >  >
 >  > ----- Original Message -----
 >  > From: "Tesla list" <tesla-at-pupman-dot-com>
 >  > To: <tesla-at-pupman-dot-com>
 >  > Sent: Saturday, January 31, 2004 12:31 PM
 >  > Subject: Re: SSTC bridge driver
 >  >
 >  >
 >  >  > Original poster: herwig.roscher-at-gmx.de
 >  >  >
 >  >  >
 >  >  > gtyler-at-drummond-dot-org.za wrote:
 >  >  >
 >  >  >  > to use a small (10-25mm ) ferrite toriod.I do this all the
time with
 > no
 >  >  >  > ringing problems, you always need a series gate resistor to
stop
 >  >  >  > parasitic oscillations though.
 >  >  >
 >  >  > George,
 >  >  >
 >  >  > I am using the F-114A-77 ones, Dan McCauley has recommended.
They
 >  >  > work without problems until now (knock at wood), but there is a
 >  >  > certain amount of ringing - despite I am using 15 Ohm gate
resistors.
 >  >  >
 >  >  > Cheers,
 >  >  >
 >  >  > Herwig
 >  >  >
 >  >
 >  >
 >  >
 >  >
 >
 >
 >