|
|
|
|
In order to test and run my projects, I need a regulated power supply unit. Now, to buy a lab PSU it might cost several hundred pounds, and even the type that high schools have aren't cheap. So I'm going to utilise a cheap source of PSUs- PCs- and modify them to suit my purposes.
Materials required:
This part's easy; there are usually 4 screws holding the unit to the ATX case. Unscrew these, and open the case. Trace the cables from the PSU to the MoBo, and disconnect them. It should just then just slide out of it's compartment and come straight out. Cut the connectors off the cables, leaving about 3 or 4 inches on the connectors for reuse. You now have a PSU ready to mod.
Inside the PSU case.
Unscrew the four screws on top of the PSU, holding the case together. This stage is probably the easiest to sort the wiring out, so sort the wires into colours; I had 4 orange wires, 13 black wires, 6 red wires, 5 yellow, and 1 white, 1 purple, 1 blue, 1 grey, and 1 green. You'll probably get about the same, with possibly a pink replacing a red, or a brown replacing an orange. These are feedback wires, so just make sure they're always attached to the correct color, and you can safely ignore them. Tape or rubber band each colour together, so they're easier to deal with later.
The wires sorted into colours.
If it's an old PSU, unscrew the PCB from the case and clean it off, with a blower brush, canned air or something. Then screw it back in.
In a free area of the case (check inside as well, for heatsinks, fan casing, etc), drill holes that will take the terminal posts, the LED indicator, and the power switch. Line them up first by centrepunching the holes, then enlarging them with a drill.
The finished holes
Now insert your components into the correct holes, and you should have (depending on your design) something a little like this:
The face plate
Ok, now it's time to start thinking about those wires again. here are the colours and their purpose:
And a picture, for you visual learners out there:
Bear in mind, the 5V (red) supply is the only one that is properly regulated, if you want the others to be also, you'll have to do that separately. There are ways to do it, but I don't think it's necessary for mine yet. On V.2, perhaps.
When you have them all soldered up and heatshrinked, it should look somewhat like this:
Almost ready to put the lid back on
I accidentally cut the wires too short, so I extended them using mains rated wire. This was so I could just use one wire per terminal, and it can still take any high current. You may also notice that I haven't used all the wires of some colours. I decided that only 4 per terminal was necessary. The two black terminals are for convenience, rather than to use up wire. One black wire went to the switch, another to the two LEDs.
Now you're finished, and once the case is on, it should look something like this:
Complete!
bravenet.com