DIY Eurorack power supply

Specification :

  • 72W Switching power supply.
  • Over temperature protection
  • Reverse polarity protection
  • -12V at 3A (3000mA) / +12V at 3A (3000mA)
  • possible extension for +5V power supply
  • Can be configured to -15/+15V
  • About 95% efficiency at 24V input
  • 8mV ripple

Material to buy

It should cost less than 20€/$ on ebay or other sources.

  • 2 x DC/DC regulator based on LM2596 (it’s very important to use a LM2596, not an equivalent)
  • 2 x radiator for LM2596 (with electrical isolating, thermal conductive paste)
  • Strip prototyping board (about 10x16cm, 4x6inch)
  • 2 x 40 pin 2.54 dual raw male header
  • Power connector of your choice
  • 20 x 100nF Capacitor
  • 2 x Leds and 4.7K resistor (optional)
  • Electric cable

Material you should already have

  • An old laptop power supply (from 15 to 36V, 80 Watt minimum)

If you don’t own one, you can buy a generic one for cheap.

Needed tools

  • Soldering iron
  • Various hand tool, screw drivers, etc
  • Multi-meter

Instructions

  • Read all this documentation BEFORE doing anything else (read the important notes twice!)
  • Fix the radiators on the LM2596 modules, and to the board
  • The radiator need to be isolated from the LM2596 PCB in order avoid electric shortcut.

  • Cut in half the PCB board (parallel to the strip)
  • Solder the module according to this schematics:

  • Yes, I know, it’s a strange connection, but it allow to convert the positive power supply to a negative power supply.
    IN- and OUT- are connected inside the module, so you should have something that look like this :

  • Plug the power connector
  • Adjust the trimer to change the output voltage (adjust to +12V and -12V) using a small screw driver

  • Cut the pin header to get 10 piece of 2×8 pins
  • Solder this pin header one next to each other ON THE SAME RAW of the board, in order to have the electrical connection between them.
  • 1st raw (the Red one) is the -12V, 2nd, 3rd and 4th raw are the ground (they should be connected together on each connector), 5th raw is the +12V. The other raw should not be connected.

  • Solder capacitor for each header between -12V and Ground and also between ground and +12V
  • Use the 2nd half of the PCB for an extension board that you can connect to the 1st board
  • Solder the LED and their corresponding resistor if you want a visual feedback of the power supply


Important notes

  • If you only need 2A or less from the power supply, you don’t need to add the radiator.
  • If you need a 5V power supply, you can add an other LM2596 module.
  • Soldering skill is mandatory in order to build this project, don’t be overconfident about your skill, you could burn your modules.
  • If you think this guide is not well documented enough, you should ask for help.
  • Test EVERYTHING before plugging the power.
  • Double test EVERYTHING before plugging your module.
  • Triple test EVERYTHING once again before plugging your module.
  • Don’t plug all your modules in the same time, but plug them one after the other.
  • I am not responsible in case of malfunction or any consequence of this malfunction.