I needed USB PD to barrel jack with multiple voltages.

This project was started when Deviant Ollam posted a video about using a USB PD trigger to barrel adapter with a barrel adapter kit instead of sorting through a bin of power bricks. The issue was that USB PD trigger only output 19V, which not all devices will tolerate.


So I found this USB PD trigger module with solder jumpers for voltage and made a shitty enclosure for it. You short the three pads to make different voltages.

Voltage│Short pad
        A│B│C
     20│0│0│0
     15│1│0│0
     12│0│1│0
      9│1│1│0
      5│0│1│1

Prototype

Just threw it together, it worked fine:

Enclosure

I got a friend to model something close to good enough in fusion 360, and then I edited in blender to adjust for tolerances.

My final STL

Assembly

The hardest part was soldering the tiny wires to the pads without shorting anything.

  1. put 30AWG wires on the trigger module
  2. glue the wires down (by the end I had found that superglue worked the best because hot glue left too much of a bump)
  3. put the dip switch and voltmeter and trigger module in the enclosure
  4. trim wires to length to reach the DIP switch
  5. strip wires
  6. solder wires
  7. put in wires for voltmeter
  8. Tune voltmeter so it’s a bit above instead of a bit below (showing 8.9V for 9V is more annoying than showing 9.1V)
  9. Pot dip switch in epoxy or superglue or hot glue
  10. put in output wires (14AWG speaker wire was just what I had lying around)
  11. glue in display and dip swith with something fast curing (my first one had epoxy leak out the front and look bad)
  12. pot the back with epoxy

Next Steps

I did monday evening when I was leaving tuesday afternoon for defcon, so it could be a lot better

  • label switches with voltage table
  • better enclosure
    • less glue, actual back
  • A more permanent barrel jack (the non-screw ones I had couldn’t fit the 14AWG)

If anyone wants to help improve this I’m happy to update this post with better stuff and credit you.

Parts