Re: Using a PC PowerSupply as a bench power supply.

On Apr 25, 2:38 pm, w_tom <w_t...@xxxxxxx> wrote:
  Not stated if these are AT power supplies (IBM PC or AT vintage) or
ATX power supplies.  Older supplies had a power switch attached to the
supply.  Newer ATX supplies are controlled by a power supply
controller and front panel switch.

  This assumes ATX type supply.  Power supply controller ordered the
PSU on via the green wire.  Then gray wire (Power OK) would tell the
power supply controller that power supply was working.  You don't care
about the gray wire signal (unless you put an LED on it to see that
message).  But you need a non-momentary switch to connect green wire
to any black wire (to reduce green wire voltage from above 2.0 volts
to below 0.8 volts).

  Some power supplies need a minimum load.  Others do not.  Which
ones?  Only answer is provided by numerical spec sheets that came with
the power supply.  Since so many marginal supplies (missing required
functions) are dumped into the market, then very unlikely anyone has
that tech specs.  In short, nobody can answer your question.  So, if a
minimum load is needed, well Radio Shack sells some 50 ohm 10 watt
resistors. Put a resistor one of the red and yellow wires.  That
should guarantee a minimum load.

On Apr 24, 11:39 am, sid <sidwe...@xxxxxxxxxxx> wrote:



I have the need to for a cheep 5/12vpower supplyand have a lot of
out dated PC(s) that I can rob the supply from, I just had some
questions about how to set it up.

There are some articles on on-line that discuss the subject but don't
really go into specifics like, if I need to draw current from the 5v
circuit to get the PS to regulate correctly, specifically how much
current do I need to draw ?  Are we talking milli-Amps or Amps ?
Also, the power good signal. I understand that that the power-good
line must be held low, but these articles state just short it to one
of the ground wires.  Back when I had circuits we use a 470ohm
resister to hold a logic signal down ?  Right ?

How do I use the power reset ?  Can I just place a momentary contact
switch in the PS case and use it as On/Off ?- Hide quoted text -

- Show quoted text -

The article discussed minimum loads, but it I don't recall where it
stated AT or ATX.
You stated the gray (power good) wire could be ignored, but I thought
that the board needed to put a signal back on this wire to turn the PS
on for the rest of the system ?
Is this not right ?



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