Re: Chopper max voltage? 297/298

Hello again,

To add to my earlier comments re:297/298 success:

I used the 1N4934, then 1N4936 diodes recommended at first and smoked
some chips.
Switched to MR851's and not only have not seen smoke, I can "Back
Drive" my machine(s) (steppers working as generators) without blowing
the boards. At least, so far! KOW.

I believe the power supply is a significant part of the success at
higher volts/amps. Mine use a 40,000mfd electrolytic, with a hi-freq
disk cap and bleeder resistor.

Calcs(and boards) I have seen would allow a 10k mfd cap.Or less. This
is for a typical bridge rectified linear PS. Have not had problems
with inrush current. I have heard conflicting info re: switching PS
with chopper-drives so I don't do it. Mariss???

Also like to use toroid transformers, but don't really know how much
they're helping, since I haven't compared with "box-style". Why mess
with success?

I do think the toroid helps if things are a tight fit. Their EMF is
"contained" better so it is less likely to interfere with something
else close by.

Ballendo

P.S. According to Tom Hopkins at SGS Thomson, The 6203 is the "real
gem" of their driver chips. It IS FET based.