This is Rev AB of the OpenCurrent, found on the sidebar. Design is completely open, and is a clone of Dave’s uCurrent. I wanted a uCurrent but he was always sold out, so I designed it using his circuit, then made it, as a short weekend project (Hahaha). It ended up taking about 3 months to get the boards in, but now they are in, and its assembled, and it works.
I tested it on the VDay card project, and it indicated it was pulling 58mA, which seems pretty spot on. Without the XBee in, it indicated 6mA. When I switched to the uA position, it read 1.5v, which I think means that it is out of its range, because in order to display the right value, it would have to display 6V. Since it’s powered by a 3.3V CR2032 battery, thats not going to happen.
Glad to finally have this project done, but I do see areas in which I can improve the OpenCurrent Design. The drill holes need to be bigger for the case screws. Shorter Banana posts need to be chosen (I had to cut these with a dremel). I accidently left the labels for the posts and some parts on, so you’ll see a J1-4. That’s pretty much it though, so I’m really happy to have it done and working 🙂
Mini update on VDay project
I’m using a RTTTL example program for Arduino, and I found about 35 ringtones to put on it (putting all of them adds 10k of flash). I have successfully made it interrupt based, so playing music can happen in the background. I will later tie the LED’s to the same interrupt (on Timer 1) so that the LED’s can flash in the background as well. Go progress!
Update: Tested it with a regulator that is supposed to have a low 2uA current, and with the open current I read 2.5 uA. My BK Precision 2709B read 2.7 uA, and the Fluke 87V read 2.5 uA. Maybe that verifies its measurements, but as far as I know, the multimeters will have a decent sized voltage drop across them that effects the measurement.