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So, a push-button switch, debounce IC, ATX power supply, and one or more
hard drives would make a happy family, huh? Hey, if there's a market
for adapting ATX cases to run without mobos, I'll start producing the
devices.
The 5W, 5ohm sounds right for 5V. The pre-made testers seem to use a
5.4ohm, 25W resistor. Sounds like they are using it on a 12V line.
(Isn't 25W too low, especially if it's encased? My calculations
suggest a 26.67W resistor. )
Tom wrote:
Paul,
The load I refered to is a "POWER SUPPLY LOAD RESISTOR, 1A" part number 113
0282. Its just a 5 Ohm, 5 Watt power resistor with a disk drive power plug.
This provides a 1 Amp load for the 5 Volt power line. The 5 V line on pin 9
is the 5VSB or 5 V standby power line. 5VSB is used to power the keyboard and
the keyboard controller (or ASIC) on the mobo so you can use the power key
on the keyboard and the wake-on-lan, etc. features. The 5VSB would be good
to use for a debounce circuit for an on/off switch. The ATX power supply
spec says PS_ON# is supposed to be debounced. I have used a piece of wire to
"jumpstart" the ATX clone power supply in a Power Computing Mac Clone
reliably. Of course the apparent lightning hit (as evidenced by the charred
modem port driver chip) probably accounted for the dead keyboard controller
chip.
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