--- Bill Bradford <mrbill_at_mrbill.net> wrote:
> On Tue, Jul 31, 2001 at 07:00:01PM +0000, wanderer wrote:
> > Since the two bulk supplies are having 8 H744's (25A versions) I was
> > just wondering about the feasebility of replacing them with standard
> > PC XT power supplies (just for the 5V), as the usually deliver also
> > between 25A and 30A, depending on the model. The large transformer in
> > the bulk supply will then be replaced with a smaller transformer to
> > deliver the LTC, DCLO, ACLO and +15V via the power monitor module
> > which is still there.
>
> How can a normal PC XT power supply deliver 25-30A, when its plugged
> into a normal 15A wall socket? Or is the amperage way different in
> the UK?
P = IE - Power == Amps x Volts
A 300W PC PSU will pull up to ~3A _at_ 110V, and will produce something less
than 60A of the various DC voltages due to loss to heat. He means
25-30A _at_ +5VDC.
Some PSUs list on the side of the enclosure what the max draw is at a
particular voltage. Older supplies were beefier at +12VDC because of
full-height disk drives. Now, +5VDC and +3.3VDC are what the chips want;
the disk drive is <20W of +5VDC and +12VDC combined.
Would it be worth protecting the PSUs from each other through a high-power
diode? The worry is that if one goes south, it'll take the rest (and
the machine) with it.
-ethan
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Received on Tue Jul 31 2001 - 13:26:23 BST