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 2: Order Your Parts!

Here is the list of parts I used in this project (affiliate links):

Ebay:

5x Binding posts (red):http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x Binding post (black):http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x Toggle Switch:http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 3mm Green LED:http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 3mm Red LED:http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

2x 220Ω Resistor:http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

Shrinking tube:http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

Amazon.de:

5x Binding posts (red): http://amzn.to/1xldoN1
1x Binding post (black): http://amzn.to/1nwk0r1

1x Toggle Switch: http://amzn.to/1xleBDV

1x 3mm Green LED: http://amzn.to/1xleBDV

1x 3mm Red LED: http://amzn.to/1xleBDV

2x 220Ω Resistor: http://amzn.to/1xleBDV

Shrinking tube: http://amzn.to/1xleBDV

Aliexpress:
5x Binding posts (red): https://s.click.aliexpress.com/e/_dZftVoF

1x Binding post (black): https://s.click.aliexpress.com/e/_dZftVoF

1x Toggle Switch: https://s.click.aliexpress.com/e/_d9dxPD5

1x 3mm Green LED: https://s.click.aliexpress.com/e/_dT0Osqb

1x 3mm Red LED: https://s.click.aliexpress.com/e/_dT0Osqb

2x 220Ω Resistor: https://s.click.aliexpress.com/e/_dTPpXjt

Shrinking tube: https://s.click.aliexpress.com/e/_dXH34Rz

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

Buy it here:http://amzn.to/1xlhJzI

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

Buy it here:http://www.ebay.com/itm/2x-10W-10-Watt-High-Power-...

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