So here, I did a thing the other day.

I have an old Tandy 1400LT (as opposed to what, a new one?) which is in really good condition bar a couple of things - no battery, and no DC power supply. I’ve previously had it running with a benchtop power supply hooked up to the battery terminals, but that pretty much restricts where I can use it and more critically takes up my benchtop power supply.

With a lot of focus in the MNT Pocket Reform community of late on the USB-C PD functionality of the sysctl, this got me to thinking - surely there’s a way of just doing the power negotiation to get a fixed DC power supply. Welp it turns out there’s a really cheap and simple way of doing that in the Adafruit HUSB238.

This is a really simple install. You get the thing, you solder on the battery terminals, cut the traces for the default supply (5V, 1A) then bridge the pads for the supply you actually want (in my case 15V, 2A) and hook that bad boy up.

Of course, it being simple meant I had a couple of minor difficulties. Firstly, it would only negotiate 15V once I actually bridged the pads for 2A despite open meaning 3A (and in theory the device should be able to draw what it wants?). I think this might be because the supply I was using was only 45W and the default voltage was just over 5V so I guess it was trying to draw over 45W? Thing was I also tried it on a 100W supply and it failed more differentlier than that. Whatever, got it working. The second issue I had was when I finally figured this out I still wasn’t getting a 15V measurement because I’d left the multimeter on continuity mode.

Go figure.