Bench Supplies Get Smaller Thanks To USB-C

Bench power supplies are an indispensable tool when prototyping electronics. Being able to set custom voltages and having some sort of current limiting feature are key to making sure that the smoke stays inside all of the parts. Buying a modern bench supply might be a little too expensive though, and converting an ATX power supply can be janky and unreliable. Thanks to the miracle of USB-C, though, you can build your own fully-featured benchtop power supply like [Brian] did without taking up hardly any space, and for only around $12.

USB-C can be used to deliver up to 100W but is limited to a few set voltage levels. For voltages that USB-C doesn’t support, [Brian] turns to an inexpensive ZK-4KX buck-boost DC-DC converter that allows for millivolt-level precision for his supply’s output. Another key aspect of using USB-C is making sure that your power supply can correctly negotiate for the amount of power that it needs. There’s an electronic handshake that goes on over the USB connection, and without it there’s not a useful amount of power that can be delivered. This build includes a small chip for performing this negotiation as well.

With all the electronics taken care of, [Brian] houses all of this in a 3D-printed enclosure complete with a set of banana plugs. While it may not be able to provide the wattage of a modern production unit, for most smaller use cases this would work perfectly. If you already have an ATX supply around, though, you can modify [Brian]’s build using that as the supply and case too.

18 thoughts on “Bench Supplies Get Smaller Thanks To USB-C

        1. I’ve a similar looking device but with only one full size usb input. The UI / UX is the reason why i barely use it – it’s too easy to mess up the voltage / max current by accident.

          I hope they improved it or use a different on the unit you’ve ordered.

    1. Yes. Also a home to live in, and some basic furniture. Possibly also clothes and shoes. And you will probably need to eat and drink something while working on it, and then wash your hands somewhere. The costs really escalate quickly.

  1. I have that same buck-boot module. It’s ok for the price, but don’t expect it to replace a real lab power supply. The current limit is managed by the microcontroller in the display module (Nuvoton N76E003 ), and therefore slow.

    Don’t expect it to protect delicate components from overcurrent/overvoltage.

    It’s ok for charging, though.

  2. I just can’t bring myself to celebrating USB-PD. It adds ridiculous complexity to something as simple as supplying a device with power. And it doesnt deliver on the “use any suppy for any device with any cable” promise. Instead all plugs only look the same on both ends, so you can never ever guess what will work with what. I wonder if it will get better over time.

    1. This has not been my experience at all. I’ve been steadily moving my gadgets and DIY projects over to USB-C, and have never had a case where I couldn’t just grab whatever charger was handy.

      Unless you’re talking about situations where you try to plug a low wattage supply (like a phone charger) into a high drain device that needs more power? I admit that could be annoying, but I certainly wouldn’t call it complex. It’s not hard to figure out your phone charger is probably not big enough to charge a laptop.

  3. Other poor load regulation and poor line regulation and poor PARD (noise) levels and no reverse voltage protection and no surge protection, looks ok to be used as a ‘bench’ power source…

    1. I mean, a professional is going to use professional tools. If you are just trying to power your hobby project with some power with tolerances in the +-5% range, it’s probably fine.

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