this post was submitted on 10 Sep 2026
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I keep a box of just old power bricks. Some are pretty normal like 12vdc@2a but some are weirder. What needs 19.5vac@5a? I don't know but when it needs it I've got it.
I have a bench variable-voltage power supply. Mine is a very low-end one, doesn't even have an integrated voltmeter, so you need a multimeter or oscilloscope or something to set the voltage.
But...if you need some kind of exotic power at a given voltage and don't have time to wait for an order to come in, one of those will fill the hole for all kinds of fixed-voltage power supplies.
I have only very rarely needed it. I've used it to provide 5V power to a PIC project that I was breadboarding, and another time tried checking whether it was low voltage causing a problem with a given battery-powered device. Maybe one or two other occasions.
If you specifically want barrel plugs, you can get "universal" adapters that will adapt one cable to various diameters and polarities.
I think that USB is also kind of increasingly filling the hole here as a universal standard for DC power on newer products.
19.5v is pretty common for stuff that needs more power, but I'd bet there's some threshold at 20v that means a device is no longer "low voltage".
But AC? Are you sure? That would be exceedingly unusual.
I think it was for a printer