After a couple of months of bitching, someone finally granted me a spare few months of spare time. In my first week of this spare time, I've been both bored, and inventive.
Sitting next to me is my now finished ATX power supply. With it, I am able to hook up my future projects to whatever voltage I desire without the need for masses of batteries, something that will no doubt save me many dollars in the future. Total cost of my money saving project: $3 plus a few hours of my spare time.
Parts required:
- That shit ATX PSU from that old PC sitting around. Under 600W, else you might as well re-sell it.
- Brain; if you have one already, then you won't need to find someone with one.
- Tools; call your nearest one over.
- Your preferred method of connecting wires (in my case, a terminal block).
- Switch; SPST is the minimum; rated to anything. You'll almost always have one in your spare parts box.
- LED's; any colour. Yes, don't lie; you do have some just sitting around.
- Two resistors; people recommend 330Ω, I used 470Ω. Reality: any that will make your LED's turn on with 5V will do.
- Heatshrink; compulsory. Yes, I know you wasted it on your last project because it's fun to use, this time you actually need it.
- Some form of non-conductive glue. Hot glue is perfect, I used bathroom sealant. Make your own choice here.
How to:
- After snipping off the assorted connectors take out your multimeter and measure the voltages from all the wires. Black is always ground, and if you don't know that, find someone to do the rest for you. After discovering that none of the wires seem to have any voltage, connect the green wire up to a black one. Try again. Oh... The green wire seems to be some sort of switch... Take note of that, as well as the voltages from all the wires. Also take note that same coloured wires are the same. Fancy that.
- Measure the internal resistance between 5V and ground. It's a switched mode power supply, and needs some sort of load to work. Mine was 100Ω. If it doesn't have a load, it might need a power resistor later on. If it works without, give yourself a pat on the back. Else you might need to look into a load later in the project.
- Leave it sit around for a couple of hours, disconnected from the mains. Anything with mains power these days is dangerous because of the quantity of components that hold power long after it is off. I've heard people recommend leaving it around for days. Your discretion here. If you feel like poking your hand around a capacitor with a couple thousand volts charged, be my guest; I take no blame for your stupidity; I did add "brain" to the parts required list.
- Open it up, once you've read the above note. Serious. I like you alive.
- Find some method for connecting a switch between the green wire and a ground one, use heatshrink to cover your shitty solder work and more importantly to prevent bare wire touching the case. Attach the switch to the outside of the PSU in your preferred fashion. I used the assorted nuts and washers that come with the switch, works a charm.
- Track down the purple, grey and two black wires and separate. Be inventive to connect up the LED's and the resistors here (series for those that are "brilliant" enough to ask). Again, heatshrink is compulsory. The purple will be your "Mains On" light; the grey your "Power Good" light. Mount. I used bathroom sealant.
- Close up that PSU. You should be done on the inside now. Test that plugging into active power lights the "Mains On" light and flicking that switch lights the "Power Good" light. Not working? See if I care, it worked for me...
- Separate the wires you want for your future projects. Can't remember what was what? I told you to write it down. Blue = -12V; White = -5V; Orange = 3.3V; Red = 5V; Yellow = 12V for most systems. Got a small brown wire? I'm informed it needs to be connected up to either 5V or 12V to work. Someone get back to me on this if that was your case. I had no such wire. Snip off the wires you don't want.
- Attach to your preferred method of connecting wires and neaten up remaining wires. I chose a terminal block because I can hook up anything with a screwdriver. I've seen people use banana plugs and mount them on the case of the PSU. It's already cramped in there in my opinion; the top of the PSU has plenty of room. If you do decide to protrude something from the case see my note before opening it up, and use heatshrink (it's like a condom for wires; protects you from shorts running around all over the place).
- Finalise... It took twenty four hours for my terminal to set in place on top of the case due to using bathroom sealant. It has a nice smell though now. Test. The case is part of the circuit, and you'll blow stuff letting wires touch it. Like the RCD in your house. It's there for your safety...
I'm now looking for more stuff to build/invent. If you have an idea of something I can build, pass it on. I have spare time and a desire to get electrocuted at least once these holidays.
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