Initial tests, DC powered computers [RE-wrenches]

[Sharkey]

	Wrenches;

	For any of you who are interested in further experiments in running PC's
on DC, I have a bit more.
	I have several old power supplies around the shop, and decided to
experiment on one this morning. Yes, the AC is converted to DC right off,
but there is also a 115/230 volt switch that connects a voltage doubler
circuit in the 115 position. The bus voltage (what the power supply uses to
convert to +12, +5, etc) is 326 volts DC when the PS is supplied 120v grid
voltage with the switch in the 115v position. Bus voltage when supplied
120v grid voltage with the switch in the 230v position is about 124v, and
+12 & +5 output voltages were normal. The voltage doubler is an AC device
and won't work with DC.
	This caused me some initial concern, as I figured that it would fail
miserably under load. What the hey.... It's an old supply, let's just smoke
it. Set the switch to 230v, power it up and try it. Applying a 10 amp load
to the +5 output didn't do a thing to the bus voltage or the +12 & +5
output voltages. The supply just seemed to work normally.
	Of course, further testing under full load conditions is warranted, and
another next step will be to feed it some DC, and then see if it will boot
a motherboard. I think it's safe to say that "overvoltage" isn't going to
be a problem, and "undervoltage" is something less than 120 VDC. Will it
overheat, blow up after a few hours or have a shorter life span with DC?
Don't know yet.
	A word about monitors. I realized that even if a monitor uses a switching
power supply, the automatic degaussing coil around the picture tube will
need to be disconnected, as it is run from AC and would probably fail AND
cause your screen to look putrid if it even sniffed some DC. More later on
this, I have access to some semi-functional monitors that I can rip into
and torture.
	Let me know if any of you are actually interested in continuing this
topic. While it *is* fun to play with dynamite knowing I won't suffer any
catastrophic losses, I could be doing something else useful, like housework...

	-S
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