Matt Mc_Carthy wrote in a message to WAYNE CHIRNSIDE:

 WC>  When the heck is someone going to produce a standard ATX power 
 WC> supply designed from the get go to be driven from either 120 AC or 12
 WC>  volt deep discharge batteries?

 MMC> They are _almost_ there.  The switching PSs can be run from DC, so
 MMC> just put 10 of those monster 12 volters together!  That should
 MMC> last a weekend or two... 

Actually they _are_ run from DC.  But if you're talking typical US power
the AC at the input is first run through a voltage doubler,  so you
woulndn't need ten,  you'd need _20_ of those batteries...  :-(

I had good luck with a few UPSs in the past,  but one of them did require
10 batteries -- only 1.9AH units,  but I still wasn't going to make the
investment as even being employed by that battery store at the time I was
looking at around $20 each.  So I didn't bother.  I still have the boards
though.

I've been looking at the specs for a lot of transistors lately.  While
there seem to be a number of parts out there that handle both high currents
and high wattages at moderate voltages,  there seem to be a lot *more*
parts which handle some nonntrivial power at higher voltages,  up to
several hundred volts and even higher.  THis initially came as a surprise
to me,  but I figured at first that a lot of them were horizontal output
transistors in tv sets and monitors,  and in this context I figure that a
lot of them are also going to be in switching power supplies as well.

I guess it's just easier to build stuff when you don't have to handle a lot
of high current...

---