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bogidon | 4 years ago

I have a poor understanding of electrical engineering so I am not sure this would actually work. But I've wondered if one could make a fairly cheap gadget for turning a decent USB-PD supply into a somewhat useful hobbyist variable voltage DC power supply.

Especially with USB-PD 3.1 which has an adjustable voltage supply mode [1] so you are not constrained to only a handful of power profiles. I think in theory you could offer 5V, 9V, and 15-48V.

It would be cool because it would be much easier to carry (keep in your backpack) and I imagine cheaper than a benchtop power supply so long as you have access to a capable USB-C charger. But I'm not sure what you'd be missing out on versus a proper benchtop.

[1] https://www.usb.org/usb-charger-pd

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varenc|4 years ago

Like Op, I also have been tinkering with USB-C PD and found another hobbyist tool on Tindie that does exactly like you describe! You can specify the voltage and current needed, and it'll then make sure you get that power from a compatible charger.

This is the one I got a while ago it and it works great: https://www.tindie.com/products/clarahobbs/pd-buddy-sink/ though there's several other options out there

bogidon|4 years ago

Oh that’s awesome. Thanks for sharing.

vatys|4 years ago

You might be better off getting a fixed power profile from the brick and regulating down to your desired voltage separately. While it's possible the brick will be well regulated, it's likely to have some noise and output voltage variability. Even for a hobbyist, the DC supply should be clean and well regulated, or you might be stuck debugging your hobby design only to realize it was a power issue all along.

A small board/box with a DC to DC regulator, knob, and display, could still be quite a bit smaller than a big bench supply, and provide reasonable performance. USB-C in (at a fixed power profile) to an output from a variable buck supply, for example.