Prices Today for a lab power supply well exceed $180. But it turns out a obsolete computer power supply is perfect for the job instead. With these costing you only $25 and having short circuit protection, thermal protection, Overload protection and varied output voltages of 3v, 5v and 12v but we will me modifying it to give out 1.5v to 24v. They are perfect for general electronics.
This is my first Instructable for what I think is a brilliant idea, I'm only 14 and i can build it
WARNING: This will void warranty's and can shock you if you don't have your wits about you
NOTE: This Tutorial is littered with bad grammar and spelling mistakes. English Teachers may want to look away now
Your going to need:
Computer PSU (I recommend 250W+)
A 10ohm, 10W or greater power resistor (Some new power supply's don't work properly without some load so this can provide that)
2 LEDs of any colour (Red and Green is the best)
If your using the leds you need a 1 or 2 330 OEM Resistor(s)
Heat Shrink Tubing
External Enclosure (Some people cram it all inside the Power supply case or you can put it in a external enclosure.)
These Depend on which method you use: (More on that later):
LM317 or LM338K Voltage regulator
100nF Capacitors (ceramic or tantalum)
1uF Capacitors Electrolytic
1N4001 or 1N4002 Power Diode
120 Ohm resistor
5k Ohm variable resistor
Step 1: Harvesting & Preping The Power Supply
BEFORE WE CONTINUE MAKE SURE YOUR POWER SUPPLY IS UNPLUGGED.
Capacitors can bite and if not give a painful shock kill you. Please discharge the power supply by letting it sit unconnected for a few days or connecting a 10ohm resistor between the red and black wires.
If you hear buzzing when you turn on the power supply it means there is a short or another serious problem. If you hear buzzing (that not coming from the soldering iron) when soldiering it mean your power supply is on. There is still power flowing through the PSU if it plugged in but not switched on
OK lets get straight into it remove the computer case and take out the screws (usually 4) at the back of the computer to release the power supply. Now take out the 4 screws on top of the case and take the wires out of the hole then group wires of the same colour together and snip off the ends.
Just To tell you , you've just void your warranty