Bench Power Supply with Three Adjustable Outputs

Today I finished a project I started a few months ago: a three-channel desktop power supply with adjustable output voltage. In the future I would like to add an adjustable current limit, but that is a story for another time.

Laptop adapters

To convert the AC mains voltage to DC, I used two adapters from old laptops. One gives 15 V, which is a little unusual since laptops mostly use 19 V, but that is what I had and I wanted to use it. The other gives 19 V.

DC-DC modules

The voltage of each channel is set by an HW-411 DC-DC module bought on eBay, with a 10-turn potentiometer, from 1.25 V to 13.5 V. The HW-411 is a step-down converter with an integrated LM2596 and has a built-in trimmer potentiometer for adjusting the output voltage. Remove the trimmer and connect the 10-turn potentiometer in its place.

Assembly

I used three of these modules and mounted them on the front panel together with the panel meters, the binding posts and the power switch.

This is how it looks inside:

Conclusion

I wanted to show how easily you can build a device like this with little effort, from old devices that collect dust in many homes or end up in the bin but can still be useful.