Introduction: DIY Lab Bench Power Supply

Everyone has those older or newer ATX power supplies laying around. Now you have three options. You can throw them in your garbage, salvage some good parts or build a DIY lab bench power supply. The parts are dirt cheap and this supply can deliver more amps than some modern variable ones. Let's build it.

Step 1: Watch the Video!

The video gives you all explanation you need to build this project. But I will tell you the most important steps again, this way you can not screw this up.

Step 3: Get the Right Resistor!

You may already noticed that we have to put a dummy load on the supply to keep it stable even when we only draw small amounts of current.

I recommend the dummy load should draw at least 0.5A.

Here is the calculation if you have most of your power on 5V/3,3V rail:

R=U/I=5V/0,5A=10Ω

P=U*I=5V*0,5A=2,5W

http://www.ebay.com/itm/10W-10-R-Ohm-Ceramic-Cemen...

Here is the calculation if you have most of your power on 12V rail:

R=U/I=12V/0,5A=24Ω

P=U*I=12V*0,5A=6W

Step 4: Make the Correct Connections!

What does each wire mean and where does it connect to? You can find a schematic here which tells you how to connect the parts. Anyway here is my written version of this schematic:

Orange (3,3V) ---> 3,3V red binding post

Red (5V) ---> 5V red binding post

--------------> 10Ω 10W resistor

---------------> 220Ω resistor of 3mm green LED

White (-5V) ---> -5V red binding post

Yellow (12V) ---> 12V red binding post

Blue (-12V) ---> -12V red binding post

Brown (3,3V Sense) ---> 3,3V binding post

Purple (5V Standby) ---> 220Ω resistor of 3mm red led

Green (Power ON) ---> One side of the toggle switch

Black (Ground) ---> GND black binding post

-----------------------> Cathode of 3mm green LED

-----------------------> Cathode of 3mm red LED

-----------------------> 10Ω 10W resistor

-----------------------> other side of the toggle switch

Grey (Power Good) --> not connected

If you have most of your power on the 12V rail then you need to connect a 24Ω resistor to 12V instead of 10Ω to 5V.

Step 5: Success!

Everything works! Now you can build even more awesome electronics projects with the help of this bench power supply!

Feel free to check out my Youtube channel for more awesome projects: