Re: Sheppard-Talyor circuit up on my website/ low Z construction technique

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

Original poster: "rob by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rob-at-pythonemproject-dot-com>


> Just an observation: it looks like using a sledgehammer to crack a
> nut. There must be something fundamentally wrong, either with the
> circuit or the way it's being implemented. No?
> 
> Regards,
> Malcolm

Yes, actually these supplies are designed to be run under closed loop
SMPS control.  With light loading the duty cycle is very small and
stresses are decreased.  When the load is increased the controller ramps
up the duty cycle.

I am trying to get a design that works open loop.  I've found that the
diodes are the culprit.  The FETS dissipate little power. Using real IR
HexFreds has made a substantial difference.  IR has an app note on how
not all 35nS turn off diodes are alike.  I now believe it.  One diode in
particular went from too hot to touch to just warm after putting in the
IR model.

I'm doing a lot of spice simulation to see if I can reduce diode
losses.  Its a challenge.  

Rob.

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