[ARC5] Fw: Smart People: 60Hz Transformers Faster

[Robert Eleazer]

"As a designer of, among other things,  switchmode power  supplies, I will say that none of them that I have seen use  half-wave rectification. Diodes are cheaper than monster electrolytics."

I have given no thought to computer power supply design and have only examined discarded examples to see if there were any usable components.  But one junker I ran across not long ago was interesting in that it had a separate module in which they very clearly took the 125V 60 cycle wall current, ran it through a fuse and a full wave bridge, followed by some big caps and a toroid before sending it off to the rest of the power supply.  The module was complete with the male power plug socket and tests showed the DC output just as you would expect it.  I figured that with some more caps added to the output that little module would be fine to provide the kind of DC power needed to run something like my BC-652-A.  I think I may even put it in a separate little box and plug it into my Variac when needed.

And David's questions also lead me to wonder again about something.  What controls the frequency of the power output of a solid state inverter or UPS?  I built one of these once, from plans in an old QST.  It used two PNP power transistors, four power resistors, and a 24VCT secondary 115V primary transformer.  Worked the first time, too!   

Wayne
WB5WSV