EX300 Micro Amps

[jyaan]

I'm getting weird readings when I try to measure uA with my EX-330. When measuring with the mA mode I get 3.9, and when measuring across a shunt resistor I also get 3.9mA. But when the meter is in uA mode, I get around 1000uA. What's going on??? I recall Dave saying the closer you get to the limits of the meter, the more you're affected by burden voltage -- and the circuit also ran on 3.3v. But the mA mode was pretty close, so what's really happening here?

[alm]

I assume that the uA range goes up to 4mA. The uA mode probably has a much higher shunt resistance than the mA mode (see DMN manual). The higher burden voltage is screwing up your circuit, which you didn't mention, somehow.

[jyaan]

The "circuit" is just an LED and resistor. I originally supplied 3.3v from a USB development board, and also tried two AAs and a 9v, but they all had similar results. Oh well, maybe I should consider getting a uCurrent.