On Sun, 6 Aug 2006 09:06:15 -0700, Dr. Anton T. Squeegee
put finger to keyboard and composed:

In article . com,
(known to some as ee_design) scribed...

Can any one tell me how to effect a simple on/off control of a standard
ATX type power supply to use it on bench or for other projects? How
does motherboard control this function?

It's usually a 'soft' logic switch. A momentary contact closure
toggles a flip-flop in the supply which turns it on. A continuous
closure of more than ten or so seconds usually turns it off.

The logic is on the motherboard. The PS_ON signal is 'hard', ie there
is no flip-flop in the PSU.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.