This instructable will show how I built my benchtop power supply from the power supply unit in an old computer. This is a very good project to do for a number of reasons:- This thing is very useful for anyone who works with electronics. It supplies nice, clean DC power in a number of voltages with overload and short circuit protection built right in!- It is a very easy project. Most of the work is already done for you inside the computer. It's just a matter connecting a few wires and you're done.- It's very cheap. I got the old computer for free and the rest of the parts were under $10. A commercially built benchtop power supply like this could run you more than $150!- It's somewhat environmentally friendly since your recycling old parts to make something new.I should mention that this is not an original idea of mine. I learned everything I know about this project from other Instructables about power supplies (there are dozens). My project is unique only because of the enclosure I built for it. The guts are the same as any other one.My particular unit is capable of suppling +12, +5, +3.3 VDC and -12, -5 VDC. These 5 rails along with the Ground rail can be mixed and matched to provide many different voltages eg. the voltage between the +12 and -12 rails is 24 volts). There is also a handy on/off switch in the front with lights that indicate how the unit is operating.Since I don't have any electronics projects on the go yet, I am only able to demonstrate a simple relay circuit. Here you can see the relay powering different combinations of indicator lights based on the state of the pushbutton.
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step 1Gather Your Tools and Get Yourself an Old Computer
The things you'll need for this project vary greatly depending on your own design but you'll definatly need:- A multimeter- A pair of wire cutters / strippers- A screwdrive…
step 2Extract the Power Supply
It shouldn't bee too hard to remove the outer case of the computer. Usually there is nothing more than a couple of thumb screws holding it on. Once you have removed the fas…
step 3Get Out Your Multimeter
Each color of wire coming out of the power supply box supplies a different voltage. All wires of the same color supply the same voltage. It's your job to use the multimeter…
step 4Build an Enclosure...Maybe?
While most people seem to add a few binding posts to the case and stuff everything inside I don't recommend it since the wires could interfere with the rotation of the fan.…
step 5Making the Connections
All wires of like colors will need to be gathered and connected together. You should remove the zip ties that bundle the wires from each molex connector. Next, cut and spli…
step 6Adding the Switch and LED's
If you don't know how to solder than there are plenty of instructables on it. In any case, you'll need to break out the soldering iron and the solder for this one.Wiring up…
step 7Finished!
And there you have it, a cheap benchtop power supply out of recycled parts. In the near future I will try to start prototyping some elecronic circuits that I will need for …
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http://www.instructables.com/id/Another-Benchtop-Power-Supply-from-PC-Power-Supply/