Turning on computer power supply SANS computer

Ragtop

I was thinking of running my Halloween stuff off of a computer power supply without the computer, but can not figure out how to turn it on.

Tried jumping power_ok to ground and then tried PS_on to ground, but no go. Should one or the other be connecting to power instead?

Mike Green

PS_ON# looks like it would be an inverted signal (#), so it would need to be grounded. PWR_OK would be an output from the power supply that indicates that the AC input is adequate for the next few milliseconds. Many PC power supplies have a minimum +5V load requirement. It may not turn on without some load (maybe 100mA or so).

PJAllen

See about pin_14 -- http://pinouts.ru/Power/atxpower_pinout.shtml

Ragtop

Mike Green wrote: »

PS_ON# looks like it would be an inverted signal (#), so it would need to be grounded. PWR_OK would be an output from the power supply that indicates that the AC input is adequate for the next few milliseconds. Many PC power supplies have a minimum +5V load requirement. It may not turn on without some load (maybe 100mA or so).

Thank you that was it. Apparently it was "on" but I was expecting the fan to come on. When I attached an led it lite up and the fan started up.

Ragtop

Would it be safe to turn on the power supply with an Optoisolator between it and the propeller?

I am now thinking of using these as wall warts for my Halloween monsters instead of running several off one power supply with relays. I have seen a lot of computers for next to nothing
at garage sales and am now kicking myself for not getting them for the power supplies.

First test using it with a drill motor was mixed. The power supply shuts off, but if I click the power "button" a couple of times to get motor kick started it will catch and run really really fast.

xanadu

I would put a small relay between the PSU ground and PS_ON.

SRLM

Ragtop wrote: »

Would it be safe to turn on the power supply with an Optoisolator between it and the propeller?

I am now thinking of using these as wall warts for my Halloween monsters instead of running several off one power supply with relays. I have seen a lot of computers for next to nothing
at garage sales and am now kicking myself for not getting them for the power supplies.

First test using it with a drill motor was mixed. The power supply shuts off, but if I click the power "button" a couple of times to get motor kick started it will catch and run really really fast.

I've used a computer power supply to power some brushless motors. The one that I used doesn't need much, if any, current to turn on. When we flipped the power switch (soldered to one of the pins) the fan would turn on.

Additionally, I noticed that some brushless motors create a voltage spike on the power rail (12v, in our case) up to about 14 volts. This occurred whenever we commanded the motor to 0 rotation while in motion, and caused the power supply to automatically turn off. I suspect that you are encountering the same thing. You'll need to add in your own circuitry to prevent this.

RickInTexas

You usually need to have a significant load (several amps) on the 5 volt rail for it to come up and run properly.

There are about 100 articles on Insructables.com on making a bench top supply from a PC supply.

Spark fun has a kit for this, http://www.sparkfun.com/products/9774.

It appears to have mixed reviews and some comments on appropriate load resistors, which the basic SF board lacks.

Don't connect to anything important without checking the outputs for proper regulation, ripple, noise etc.

idbruce

Put a 10 ohm 10 watt resistor available from RS on the 5V rail and it will power up everytime.

NWCCTV

You can pick up a PS tester for about ten bucks. (Check with erco, maybe he can find a cheaper one). Then you can use the vairous test ports for your power. As soon as you plug in the main power cable it will kick on the power supply.