Specification :

48W Switching power supply.

Over temperature protection

Reverse polarity protection

+12V at 3A (3000mA) / -12V at 1A (1000mA)

possible extension for +5V power supply

Can be configured to -15/+15V

About 95% efficiency at 24V input

8mV ripple

Warning

I’ve got feed-back of unsuccessful build of this power supply. Unfortunately, without having access to the build, I was not able to help or to understand why it was not working. I hope it will work for you but I can not provide assistance.

UPDATE : Some DC/DC regulator are now based on LM2596-5 : THEY WILL NOT WORK. It is very important to check that the board is based on the LM2596-ADJ!

UPDATE2 : I was told (thanks fg) that only LM2596-ADJ jm88rp, jm74rp or jm84rphs works. hw411 board with LM2596-ADJ jm97rphs don’t works. So I did not recommend using this schematics anymore. I keep this page online only for archive.

Material to buy

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

2 x DC/DC regulator based on LM2596-ADJ (it’s very important to use a LM2596-ADJ, not an equivalent, not a LM2596-5)

2 x radiator for the 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