[simpits-tech] Power Supply

[Gene Buckle]

On Wed, 24 Sep 2003, Robert Bibber wrote:

>
> I did my AC power over the weekend - I'm pretty good with regular 110V
> household electrical systems so that was no problem - now I just have to
> find a toggle switch rated for 15 - 20Amps at 120vac so I can use is as
> my Main PWR switch. From the 15 (preferably 20) amp main power I will
> split off a 10amp feed for the PC and use the rest for auxiliary power
> systems. I DO NOT want to have the PC getting starved for power and I
> think the 400W power supply in it draws like 8 amps or so. I still have
> two 115VAC cooling fans that need power as well as numerous 12VDC fans
> for circulation (I tried it out last night with only one fan and with
> the 12V lights on it got rather WARM & STUFFY in there!).
>
Instead of looking for a heavy rate toggle switch, go get a surplus relay
that has an AC coil.  Then you can use a normal toggle switch to activate
your AC mains.  It's a lot safer to do it this way as well.

 > I just tried
activating this PS like you said
but no dice. > This is Dell's proprietary power supply - not an ATX plug.
>
> When plugged in, the only pin with power is #11 (PSON). I tried
> connecting this to pin #5 (PWRGOOD) with no results. No other pin has
> power. (I have to do this stuff here at work because I FRIED my
> multitester at home and they have a NICE one here!).

When you test it, the +5V line won't show power.  The power supply will
present power on the bus until it knows it has no power good signal.
Since you haven't tied the +5v into the power good line, the power supply
comes up active for a few milliseconds before shutting down.  A consumer
level meter won't even react to a change that fast.  Unless it's a _VERY_
fast circuit, you can watch the fan inside the power supply "twitch" when
you power up the supply.  This happens as the magnetic field in the motor
begins to form, but collapses before it can fully engage the permanent
magnet in the motor.

BTW, if it's an ATX supply, how are you turning it on?

g.