Making a test power supply

I had an old 200W power supply from a ****ty Gateway machine lying around and as it's pretty much usless for most PC's (it doesn't even use a standard ATX mounting) I thought I'd turn it into a test PSU so I can check fans or USB powered devices, or just when I need either 12v or 5v power for something.

So here's the PSU as I started:

With it opened up you can see all the wires going to the circuit board. I don't need most of these.

So I trimmed it down to only the ground wires, the yellow 12v wires, the red 5v wires and the green wire I need to turn on the PSU.

Rather than use the original hole in the top where the wires came out before, I fed them through a small hole that was already in the end and then put heatshrink over the wires and fed it through the hole before shrinking it down. that will stop the wires from having any chance of wearing through and shorting.

I thought I still had a couple of small project boxes lying around, but if I do I don't know where, so tomorrow I'll head down to the electronics shop and pick one up. I'm going to have the wires feed straight into the small project box which I'll mount on the end of the PSU.
I'll have a couple of molex plugs, a couple of USB plugs and a couple of three pin fan plugs mounted in the project box, along with a switch for the PSU.

why don't you mount the molex plugs and others on the psu case? then its 1 neat little box instead of 2.

I see all of the wires are hanging out through that hole. The green one and one of the black ones (uh oh, there's a bunch) need to be shorted, so you may want to cut those really short, and short them inside the PSU box.

Thanks for the ideas and concern, but there is method to my madness.
Mal, the reason I'm not shorting the wires inside the case is because I want a way to turn the PSU on and off. There is no switch on the back of this PSU, so I'll be putting the switch in the project box. All the ground wires lead back to the same spot, so it doesn't matter which one I use for what.

I've just got back from the Electronics Shop, so I'll finish this off over the next couple of hours.

Quote:

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Originally Posted by Bucko

Thanks for the ideas and concern, but there is method to my madness.
Mal, the reason I'm not shorting the wires inside the case is because I want a way to turn the PSU on and off. There is no switch on the back of this PSU, so I'll be putting the switch in the project box. All the ground wires lead back to the same spot, so it doesn't matter which one I use for what.

I've just got back from the Electronics Shop, so I'll finish this off over the next couple of hours.

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Ahhh, now I see...

And I wasn't aware they all went to the same spot. Hooray, I've learned something today! It's like school all over again :p.

They all go to the same spot on this PSU anyway. Bigger and better ones may well be different.

It's all finished and working!

Here's the final few steps I took.

First off the project box with the holes roughly cut out:

Then I attached the box to the end of the PSU with a couple of screws and started on the Soldering. I attached the plugs to the box with epoxy:

A couple of shots of the finished product. I didn't end up worrying about USB connectors as they are easily available on the front of my computer anyway. I added a car cigarette lighter socket, male and femae molex plugs, two 3 pin fan plugs and on the side I got a spring loaded speaker connection if I want to hook something up to 12v which doesn't have any sort of plug.

The power switch on the other side:

And finally a shot of it happily running a fan from a 3 pin and from a molex:

Hopefully you can see why I wanted to use a project box on the end rather than try and put all that in the PSU itself. Besides, plastic is a lot easier to cut with a dremel and file it to size.

Awesome idea man! I gave you a rep in the other thread. Man, I've got so many ideas in my head right now. Little projects n stuff. I can't wait to get my own house!

Thanks. I've just finished it off with a coat of black paint. Once it's dried I'll add another picture.

Black paint to just finish it off a little:

wow that came out better then i thought it was, i though it was gonna be a smaller plastic box and not attached like it is. nice job +rep.

Nice! makes a modder's life easier! ;)

I found a cigarette lighter I got for free last year some time. I was digging through a box of goodies and found it again, so I thought it's power switch style suited this mod so I chucked it in.

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Originally Posted by Bucko

I found a cigarette lighter I got for free last year some time.

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:eek: what??? Even if I don't understand waht you're saying, you made a great job on that. If I can find mine, I'll show you, but I'm moving so everything (exept this comp) is packed. Really nice touch to paint it and power switched it. +rep

I was given that blue car cigarette lighter last year and promptly lost it when I threw it in a box of electrical bits and pieces.
I happened to come across it while looking for something else.
It is supposed to resemble a power cut off switch like you would see in a race car, but I wouldn't ever have it in the dashboard of my car. To cheap and tacky. However it kinda suits the power supply.

I like it, would be handy to have around for sure!

I've got an old ATX 230W PSU which came with my old case. I want to do something like what you did but the only cables I want are the molex ones for testing water cooling loops, fans etc. The power supply has a switch at the back but how will i go about getting the power supply to turn on with out being plugged into the motherboard?

You need to hook up the green wire that's in the 20 pin motherboard plug, and earth it to a black wire. I did that through the switch on the side and ran the green and a black wire up to it as my PSU has no switch on the back.
If yours has a switch, then the green and black can be attached together permanently and just use the switch on the back to power it up and turn it off.

Here's a link to a tutorial on it: http://www.gideontech.com/content/articles/196/1

It shows you which wires to join.

Thanks, that's a great help. Also when I snip off the extra cables I don't need do I need to do anything with the exposed wire stubs or is it safe to leave them how they are?