USB current probe
Sometimes it is necessary or at least ingesting to know how much current your circuit is drawing when connected to the USB port. You could detach it and hook it up to another power source but this can be cumbersome if you’re changing things around and doing programming / debugging at the same time. So I made myself a small USB extension cord with a 2 pin male header so I can attach the mulitimeter.
Bill of materials
- 1 USB cable. I had a bunch of small 10” male / female USB extension cords so I used one of those.
- 1 small piece of strip board
- 1 two pin male header
- 1 pin jumper, I pulled one of an old hard disk (the ones for selecting master / slave etc.)
- Optional a small box to make it more solid.
It’s not much of a build really as you only need to cut the cable in two. Solder each color to the strip board so the colors match up. For the red power wire you cut the strip and use the header to breach the connection. That’s really it. Now with the jumper on the 2 pin header it works like any regular USB cable. Remove the jumper and attach your mulitmeter to measure current drawn by you circuit. As long as the mulitimeter is attached you can program and debug the device as usual and have the current reading at the same time.