Based entirely on µCurrent by David Jones at EEVBlog.
µCurrent allows accurate measurement of micro and nano amps with a low burden voltage by outputting one millivolt per micro/nano amp. See the link above for all kinds of awesome if you want to know more.
This is a slightly simplified variation on µCurrent that allows for measuring micro and nano amps only. I used DPST switches and remove the milli amp measurement and the battery test (I can just probe the battery). The board is layed out for single sided home PCB manufacuring. I used a few through hole resistors for the non precision components to avoid extra jumpers.
I've included a 3D printed case as well. Just melt the tabs down once the PCB is in place.
The crazy thing is that you can measure very low current things, for example an LED will generate current! I got about 160na when pointed at an indoor light. My project running on a PIC10LF320 in sleep mode is using only 560na. Cool!
You can also hook this up to a scope for even more sensitive measurements and detail. The amplifier used is very accurate and low noise.
| Part | precision | size | qty |
|---|---|---|---|
| 100R | 5% | 1/4w | 3 |
| 100K | 1% | 0805 | 2 |
| 1K | 0.1% | 0805 | 1 |
| 75K | 0.1% | 0805 | 1 |
| 24K | 0.1% | 0805 | 1 |
| 10K | 0.1% | 0805 | 1 |
| 10R | 0.1% | 0805 | 1 |
| 100nF Capacitor | 0805 | 3 | |
| SPDT Slide Switch | PCB .1" | 2 | |
| Lithium Battery | CR2032 | 1 | |
| SMT Battery holder mouser part | 20mm | 1 | |
| MAX4239ASA+ Opamp | SO8 | 1 | |
| LMV321AS5X Opamp | SOT23-5 | 1 |
I used some springs I scavenged from some old RadioShack learn electronics kits instead of banana jacks or binding posts.