How to Build an Affordable Variable Power Supply Using an Old ATX

I made a variable power supply with an old ATX for less than $ 20 for my for my future electronic projects

Tools:

1. 3D printer
2. Equipment for soldering electronic components
3. A drill
4. A glue gun
5. Screwdrivers

Material used:

1. 1 old ATX power supply
2. 5 red female banana connector
3. 4 black female banana connector
4. 1 green female banana connector
5. 2 switch
6. 1 linear potenciometer (b10k)
7. 2 3mm red led
8. 2 330 omh resistors
9. 1 40mmX40mm fan
10. 5 3A fuses and their cases
11. Mini Digital Voltmeter with 10A/0 to 100VDC Ammeter, 3 Digits, 0.28"
12. DC-DC Step Up e Down Xl6019
13. hot glue and heat-shrink tubing to protect the circuit
14. PLA
15. 8 screw with bolt (here is 5mm screw)
16. 1 Perfboard Prototype Universal Board

You can reuse the wires removed from the ATX.

If you don't have a 3D printer, you can use other methods to create the case.

As we can see, each color has a specific meaning. Regarding output voltage, we are interested in the yellow and blue wires for +12V and -12V, the red for +5V, and the orange for +3.3V. The brown wire is used to sense/control the orange output. To turn on the ATX power supply, we must connect the green wire to ground. To test if your ATX is working properly, you can bridge these two outputs with a paperclip.

The purple wire is always live (powered). The gray wire is used to check if everything is functioning correctly once the green wire is grounded. Therefore, the purple wire indicates when the power supply is connected to the mains, the green wire will be connected to a switch to toggle the output, and the gray one will act as a status check. Once we have chosen the wires we need, we can unsolder the others to keep only the useful ones.

For the case, we created a 3D model with all parts attached. To make printing easier, we chose to split the case into four parts and join them using superglue. PLEASE NOTE: Do not solder the entire circuit before mounting the components into the box, as some components must be fitted into the casing first. For the knobs, we used a pre-made 3D model which you can find here. For the cooling fan, we decided to secure it with hot glue as we didn't have the appropriate screws on hand.

To solder the components, we followed the wiring diagram. Note that we used a perfboard for the two indicator LEDs. We also used 3A fuses to protect each output individually. We had to unsolder the blue potentiometer from the buck-boost module to solder the new one in its place as well.

To attach the case to the ATX power supply, we glued the parts of the case together and fixed the front panel with four screws. After that, we drilled four holes into the ATX casing. These holes are used to secure the 3D-printed case to the ATX unit. To reinforce the joint, we also used hot glue to bond the two parts together.

The power supply is now ready for use!