Another Bench PSU

[Technochicken]

After reading x88x's most recent bench PSU build, I decided I would make my own. I started out with a PC Power and Cooling Silencer 470 power supply. While it supposedly only supplies 30 watts less than the 500 watt version x88x used, it can handle significantly less on the 12 volt rail- 26 amps as opposed to 35.

As you can see, it is already pretty crowded in there:

Add a switch:

Add connectors:

The internal connections use these connectors. The blue wire is the -12V connection:

Switch:

Here are the wired connectors. I used three wires per connector, for a total of 6 12 volt wires, 6 5 volt wires, 3 3.3 volt wires, and 12 ground wires. In hind sight, that was probably overkill.

The grey wire puts out 5 V when powered on, so I put in an indicator LED:

To provide some load, I used these resistors I had lying around:

Wired up:

Closed:

On:

Voltage range:

After a little testing, I opened it back up to see how hot the resistors were getting. The 5 Ohm one at 5 volts got hot enough to melt the hot glue it, so I made a heatsink for it:

Then I mounted that, with the help of some thermal paste, to one of the main heatsinks:

Done! This should be more than powerful enough to power anything I'll be working on.

[x88x]

Looks great. I like the bolt-on jacks; makes hookup a lot easier. BTW, I ended up not putting a switch on my second one because it just felt pointless to have two power switches, and one of them ended up just always staying on anyways.

[Technochicken]

So did you just permanently connect the green wire to ground?

Those bolt on jacks were actually horribly designed. They come with insulating washers, but the bolt that goes through the casing is still metal, so if you don't insulate it you will short out the connection. I ended up having to put a small piece of heat-shrink tubing between the two insulating washers on each jack.

[x88x]

Yup. Just tied it straight to ground and use the main power switch to turn it on and off.

That's a shame about the jacks.