Turn an Old PSU Into a Bench Supply

You aren’t still fumbling around with wall warts to power your electronics projects, are you? Finding one that supplies the right voltage and sufficient current can be such a pain. Worse yet, these power supplies are notorious for not quite delivering what they promise — the voltage may not be exact and they often can’t provide as much current as they claim.

So knock it off already! A bench power supply is one of the most important tools an electronics hobbyist owns, so it might be time for an upgrade. Sure, they can be expensive, but they certainly don’t have to be. In fact, you can even build your own for a few dollars if you put some old hardware to work. YouTuber HANDMAX Workshop just demonstrated how you can easily do this with an old computer power supply.

The build is centered around a decades-old ATX power supply unit (PSU), a piece of hardware many makers already have collecting dust. These units are surprisingly capable, offering stable 3.3V, 5V, and 12V rails right out of the box. Instead of letting that capability go to waste, the project transforms it into a polished, modern lab tool with both fixed and adjustable outputs. After disassembly, cleaning, and a fresh coat of paint, the PSU is ready for a second life — retaining its original AC input and cooling fan to ensure safe and reliable operation.

The real upgrade comes from pairing the PSU with a 120W buck-boost converter. This module allows users to dial in virtually any voltage from 0 to 36V, complete with a built-in LCD that displays voltage, current, and power in real time. By feeding the converter from the PSU’s 12V rail, the system gains flexibility that typical fixed-output supplies lack. The adjustable output is routed to both banana sockets and an XT60 connector, making it suitable for everything from breadboard prototype circuits to higher-current applications.

To bring everything together, the creator designed a set of custom 3D-printed parts, including an extended enclosure and a clean front panel. These additions provide space for connectors, controls, and a USB fast-charging module powered directly from the 12V rail. Fixed banana sockets for 3.3V, 5V, and 12V are also wired in, offering quick access to standard voltages without any adjustment required.

Once assembled, you’ll have a compact, versatile bench supply that rivals many commercial options in functionality — yet costs a fraction of the price. With adjustable output, multiple fixed rails, and USB charging capability, this project demonstrates just how much potential is hiding inside old, forgotten hardware.