Good multimeter for uA current range readings?

Other Hardware General Electronics
1

Hi all,

I need an affordable (say under £100.00GBP) that will give good readings of very low current consumptions as I try to get low power arduino projects working.

I have thought that maybe the Fluke 17B+ would be a good candidate, but what others are there that are good for low power DC current?

Thanks

2
3

Google "op-amp current meter" for some ideas that might save you £100.00GBP. :slight_smile:

4

If you use a 1kohm resistor as shunt between +battery and +Arduino,
and measure voltage across that resistor, then 1mV = 1uA.
mV value measured is also volt drop between battery and Arduino. See if that's still acceptable.
If not, 1mV = 10uA for a 100ohm shunt.
Leo..

5

I think ebay sells simple cheap led current meters for like $5.00? Haven't got one yet, but was curios.

6

skywatch:
Hi all,

I need an affordable (say under £100.00GBP) that will give good readings of very low current consumptions as I try to get low power arduino projects working.

I have thought that maybe the Fluke 17B+ would be a good candidate, but what others are there that are good for low power DC current?

Thanks

One technique I've used on occasion is add a diode in series with the load, and measured the
forward voltage across it - a logarithmic proxy for the current, and you have to do some calibration, but
unlike a 1000 ohm shunt a diode can handle high currents when are required without dropping
much more voltage. In particular this worked for measuing a micropower wireless data sender
circuit which was a few uA on sleep mode, but 50mA on transmit - even a 100 ohm shunt would have
been too high for transmit, but too low for low uA readings.

You do need to allow for the input resistance of your meter though, but a 10Mohm meter measuring
0.25V Vf for instance is only 25nA out.