sharez said:
Looking for any information on how to possibly convert a standard ATX
psu to run off of DC input (say 12-30v). I know there are commercially
available DC-DC psu's, I'd just like to make use of one or more of the
old psu's I have lying around.
Not without a lot of work.
The ATX supplies, in general want something over 300VDC into the primary
of their transformer (some 115V supplies only want about 150v, but most
use a switchable input topology, with a voltage doubler connected when
115v is selected), so conversion, would require complete redesign of the
main transformer. Not a small task.
If you are not worried about efficiency, then you could make a DC to AC
inverter, and leave the ATX supply as it is. There are plenty of circuits
for these on the web, but be prepared for how large the transformer will
need to be for a unit able to run a ATX supply.
Given that you should not need the isolation offered by the ATX supply, a
DC-DC buck inverter, would be simpler and cheaper to make, and could feed
the main PC rails. There are off the shelf IC's, which control an external
FET to give this sort of supply, which in combination with a suitable
inductor, and a couple of discretes, would give one of the rails, for only
a very few dollars. Some rails you can probably ignore (The -5v rail has
been dropped from the latest ATX specs, and many boards do not
require -12v, except for serial ports).
Unless you have a very big DC source, you might be much better off,
assuming this is to run a PC, looking at a board and processor
specifically designed for this sort of operation. A typical modern PC,
will draw about 10A at 12v, continuously, and may peak at over 30A.
Conversely, a proper 'low power' system, based on something like the
Mini-itx board, with 2.5" disk drives, and basic video card, will have
only perhaps 1/4 the performance, but typically draw less than a couple of
amps...
Best Wishes
