Build Your Own Variable Bench Power Supply

As you go about working on your electronic projects, you’ll quickly find that components require a multitude of different voltages. One microcontroller might require 5V, while that same voltage could fry another microcontroller. Some motor drivers can only handle 6V, while others can operate on many times that. For that reason, a variable bench power supply is a very handy addition to your toolkit. You can purchase one, but they tend to be a tad pricey. An alternative is to follow this guide to create your own variable bench power supply.

This power supply was designed by Zak Kemble, who had built a similar version a decade ago. That did, however, have some small flaws which Kemble has addressed with this new design. While many consumer variable bench power supplies have current-limiting and voltage readouts, this design is a bit more basic. But it does still allow you to switch between 5V, 12V, and 19V. A current sink is implemented in order to overcome the minimum load of the voltage regulator ICs, so you can use this variable bench power supply even with very small loads like a single LED.

Unlike the previous design, which was built on a stripboard with through-hole components, the new version utilizes a custom PCB and many surface-mount components. In addition, there is a large heat sink and fan to dissipate the heat from the voltage regulators. The regulators are controlled by a Microchip ATtiny10 microcontroller and DC power to the board is provided by a standard laptop power supply through a 2.5mm DC jack. It may not be as fancy as a variable bench power supply you can order from somewhere like Amazon, but the total build cost should only be half as much. Kemble has also made all of the design files available, so you can customize this power supply to fit your individual needs.

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