An essential companion when working on a ultra-low-power projects! If you’ve ever used a portable multimeter (even your $300 Fluke!) to measure sub-uA currents – say for a low power microcontroller or sensor project – you may notice that you’re not getting the precision you expect, or that your project is acting finicky.
How is this possible? – It’s called Burden Voltage. Many people are aware of Burden Voltage, but few people are aware of how bad this effect can be in practical circuit current measurements with a multimeter. Don’t believe it?, take this simple test with your multimeter:
- Try to measure 190mA on the 200mA current range (pretty simple huh?)
- Read your manual to find out your meters “burden voltage” (I bet you don’t know it off the top of your head) (e.g. a Fluke 87V is 1.8mV/mA)
- Do the simple math to see what voltage your meter is dropping (e.g. 190(mA) * 1.8mV = 0.342V
- Now calculate what effect this drop has on your circuit at 5V, 3.3V, or something like today’s modern devices that need 1.2V supplies.
Is your 1.2V circuit going to work the same at 0.86V?, or your 3.3V circuit at 2.96V?, or even your 5V circuit at 4.66V? That’s what a high-end Fluke 87V meter will do to your measurement!, and that’s a GOOD meter. Even if your circuit “works”, what will that change in voltage do to your current consumption?
The solution? Use a precision op-amp circuit designed specifically for measuring ultra-low currents. That’s what the uCurrent is! Keep it handy for when you need to tackle those low-power projects.
Each order comes with a pre-built and tested Rev 3 uCurrent adapter. Australian Made ABS box. Fully assembled and tested in Australia. PCB is made in New Zealand by CircuitLabs. No test leads are supplied, you have to supply your own for your own purpose.
Have an amazing project to share? Join the SHOW-AND-TELL every Wednesday night at 7:30pm ET on Google+ Hangouts.
Join us every Wednesday night at 8pm ET for Ask an Engineer!
Learn resistor values with Mho’s Resistance or get the best electronics calculator for engineers “Circuit Playground” – Adafruit’s Apps!
Maker Business — Exclusive interview with Fred Dart – CEO of FTDI @FTDIChip #FTDI @adafruit
Wearables — Stabilize your Project
Electronics — Damp Sponge vs Drenched Sponge
Biohacking — “8-Hour Sleep Album”
No comments yet.
Sorry, the comment form is closed at this time.