Thread: Computer supply to Servo/Wiper motor conversion

Tweet

Hi all,

I just saw this on SparkFun's site. It's an board that adapts an ATX computer power supply connector to binding posts - perfect for anyone trying to power servos or wiper motors!

Click image


- Hook

Hmm. This looks pretty cool but why does it have 5A fuses? Don't power supplies have built in load limiters? Also a 300W supply could run 25A at 12v and I'm sure you'd need more than 5A for some of the stronger motors out there. Also it lacks the load resistor, as mentioned in several comments, which, while not necessary for all power supplies, is probably still a "good idea" to have. It would be really cool to have something like this in a small external box easily clipped to the side of an ATX power supply, already set up with the resistor and no fuses so that you could simply jack the ATX plug into it and go.

Originally Posted by Xane

Hmm. This looks pretty cool but why does it have 5A fuses? Don't power supplies have built in load limiters? Also a 300W supply could run 25A at 12v and I'm sure you'd need more than 5A for some of the stronger motors out there. Also it lacks the load resistor, as mentioned in several comments, which, while not necessary for all power supplies, is probably still a "good idea" to have. It would be really cool to have something like this in a small external box easily clipped to the side of an ATX power supply, already set up with the resistor and no fuses so that you could simply jack the ATX plug into it and go.

A good high quality PC power supply would indeed have protection built in, but it's becoming less and less common as PCs become more of a commodity. I'd imagine since it's meant to convert a PS to a bench power supply they've included the relatively low amperage fuses just to be safe.

Older PC power supplies needed a shunt resistor to help regulate the switching circuitry & prevent runaway, but they're generally not needed now. The resistor is still a good idea though, as most PC supplies have some fairly large capacitors that can store enough of a charge to do some damage if you're not careful. That said, I've used them both ways with no problems. I've built a box much like you're talking about with an ATX motherboard jack & a switch - works great, & I don't have to hack a power supply to use it.

I frequently get trade in PC that I can gut. So I have a few power supplies. My question is what wires need to be shorted to turn on the supply. If someone can post that I would appreciate it. Trying to trace the connection from the motherboard is a bit tough. The majority of wires coming from the main connector are orange. black . red. There is one yellow. One blue. One thinner grey. One thinner green.


Uh nevermind. I went and did a google search. Must be 10 how to's. LOL !!!