Re: Calculating the drain I - SSTC

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

Original poster: "S.Gaeta" <sgtporky-at-prodigy-dot-net> 

Thanks Steve,

That's a very simple solution, and I really like simple solutions!

That's why I picked this self resonant design in the first place! Well, at
least it looked simple!

Time for me to raid a garbage pail to get a LV transformer for the ICs. Sure
I can afford to buy a brand new one, but this way is more fun. I found the
whole power supply except for the LM317 by dumpster diving. Unfortanately
its transformer was N.G. - open primary. Probably sitting in the rain for
too long. :-)

Sue

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, December 28, 2003 1:09 PM
Subject: Re: Calculating the drain I - SSTC


 > Original poster: "Steven Ward" <srward16-at-hotmail-dot-com>
 >
 > Sue,
 >
 > There is a small trick to help reduce that cross conduction.  Use a 10 ohm
 > resistor on the gates of the fets, but, in parallel with that resistor
 > place a 1n5918 (schottkey, same ones in your 442X gate driver
 > protection).  Put the Anode towards the gate.  In this manner, there will
 > be 10 ohms of resistance for the RISE times, but the schottky will short
 > out for 0 ohms of resistance on the FALL times.  This should help with any
 > cross conduction at the expense of adding the 10R to slow down the rise
 > times.  Im using this method for switching my big 80N50 mosfets because
 > they turn ON faster than OFF, so there is a chance of a bit of cross
 > conduction if one fet turns on before the others turn off.  Also, there
 > will be more ringing on the falling edge of the wave because the 10R is
not
 > dampening it, so make sure to employ some 15V back to back zeners to clip
 > any negative (or possibly positive) voltage spikes.  Good luck!
 >
 > Steve