On Thu, Feb 12, 1998 at 10:56:32AM -0800, Ted Lemon wrote:
> > Well, the current SMPS machines have capacitors which charge to the peak
> > value of the input voltage.  With sine wave input, the input current is
> > zero until the voltage approaches the peak voltage, then drops back to
> > zero for the rest of the half-cycle.  So, a square wave would be better
> > (the peak current would be lower, for example).
> 
> All this might make sense if the AC power was not being run through a
> step-down transformer before being regulated and smoothed to produce
> the nice 3.3/5/12V DC that your digital electronics are expecting to
> get.

True, and all power supplies used these days (except for the cheapest
and smallest toy transformers) are switched power supplies which first
rectify and filter the mains voltage, turning it into DC.  After this,
the power supply doesn't even know whether the input waveform was sine
or square wave or something in between.  So, most things you connect to
UPS really don't care.  (HiFi equipment still uses mostly linear power
supplies for less HF noise and cheaper price (everything but power amps
require only a few watts which doesn't call for SMPS yet).)

> 	|\            /|	      |\	    /|
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> 0     |	       |	      |		     |           0
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>------ |              | ------------ |		     | ---------
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Is there anything a good artist can't do with ASCII graphics? :-)

  -jm