Making a power supply usable for non-computer stuff?

[GX93117]

OK, anyone know which wires to short on the powersupply so that it always think the power button is pressed on the computer? I want to use it to power some 12v stuff i have but don't know how to turn it on. I plan to just use to switch in the back to turn it on and off...but i need to know how to enable the power control signal. Btw its an old AT power supply but i guess info on an ATX one would work to. Anyone see any danger in doing this? Well, any help is appreciated =)

-GX

 

[Killbat]

Most AT-powered motherboards will only start up when they recieve a "power good" signal from the supply (I think the line starts high and then drops? ah, well), but the AT power supply itself is controlled only by the phat power switch in most instances. You must have an unusual AT supply? Does it have an additional 120V switch or something?

 

[MiniThug]

Thats an unusual idea you have there. what kind of stuff do you plan on powering. Sounds pretty interesting to me.

 

[DARRIN]

Short the green to any of the blacks. I can't remember if it's just momentarily or keep them shorted.

 

[BigLance]

I have done what you speak of,

It is the green wire and for the ATX powersullpies I used it was a constant connection that made them stay on, I just threw a toggle switch on them.

Have fun !

 

[jamarno]

ATX supplies need their green Power_On signal on pin 14 to be shorted permanently to ground (any black wire on the connector, like the two next to the signal) to turn on.

Both AT and ATX supplies really need a load of about 2 amp on the +5.0V output to provide good regulation, and some AT supplies won't put out +12V without this. This load can be provided with a total resistance of 2-3 ohms with a power rating of at least 40 watts, such as with 4 separate 10-ohm, 10-watt resistors, each connected between a red and black wire. Be sure the resistors are rated for at least triple the needed wattage because at their rated power, resistors run at 100 Celcius.

 

[GX93117]

Woohoo, thanks for all the info guys... Yeah you're right Killbat, I forgot that the AT don't have that switch in the back. That should make it even easier, you don't even have to short it i think. Well, I was planning on running some car equipment on it. Just gonna power my amps connected to two 12" subs. I know there's not gonna be enough current but should be fun to see how stron it is. I already tried it with some cheap 3A PS i made in ece class and it was louder than i ever wish to turn it on (pretty loud). Hmm...i wonder if i should use an ATX PS now?

 

[MiniThug]

Hmmm, let us know how this works out. It will be quite interesting to see. I was thinking about doing the same type of thing in my house since I have a 12" and a car amp just laying around going to no use. Didnt think it would be practical though. But if you get it to work, Ill prob give it a shot too.

 

[Killbat]

IMHO, a run-of-the-mill computer supply doesn't have nearly enough balls to run your subwoofers like a car's power system. With a common AT supply, you'll probably have 100W on the +12v line, and even then you're pushing it.

 

[DARRIN]

Should work at low volumes. Most power supplies only put out about 10amps on the 12 volt line which is 120 watts. I would not try to hook a subwoofer to it though.

 

[BowDown]

Just beware that a 250watt PS only puts out like 125watts (ruff estimate) for the 12v circut... So if you run a 200watt Car amp that draws 3->5amps of power you might fry the PS.

I have a nice 10amp electrical hobby grade redundant supply. I can adjust the voltage to the normal car voltage (13.x volts) and keep a continous amount of power going to it without strain.

Good luck with it...

 

[BowDown]

Damn you guys are quick!

 

[MiniThug]

Well are there any other cheap solutions for what he is proposing to do? You guys seem to know a lot about the subject.

 

[BowDown]

Hmm... Car battery charger would be a cheap alternative.
Or you can get a 10amp 12v PS from radioshack for like $30 I think...

 

[Killbat]

The slickest solution would be to get a dandy adjustable regulated supply, you could have 35A or more easily, and so well regulated it hurts. Cheaply, though, you could get up to 8A from a car battery charger, but I wouldn't mess with that, VERY noisy power. You're probably looking for a small 10A+ 12v supply from RadioCrack, like Bow said.

 

[MiniThug]

How many amps does a cars alternator put out?

 

[Killbat]

Enough.

Seriously, though, I think alternator ratings vary by car. Check your car's manual.

 

[BowDown]

Usually about 50 -> 120amps .