anyone ever used a uCurrent reader from eevblog?

Other Hardware General Electronics
1

Hello,
I've seen a few mentions on this forum of the uCurrent reader from eevblog. I'm still a newbie at electronics, and I could use some clarification on how to not overload this device.

From the PDF for the uCurrent, it saids not to put more current than the range for that current selection, or else you might blow the shunt resistor. This is the top end for each range selection.

300mA [mA range]
1mA [uA range]
1uA [nA range]

Let's say I have a microcontroller that sleeps for 10 seconds, wakes up and lights up LED, and then sleeps for another 10 seconds. I want to measure sleep current. I would keep the selector switch in [uA range] to measure the sleep current consumption. But when the microcontroller wakes up, the wake up activity consumes more current than the 1mA allowed in the [uA range]. Would that blow the shunt resistor? Would I have to move the selector switch from [uA] to [mA] quickly before the microcontroller wakes up? It seems like a pretty risky operation. Wondering if my understanding of overload current is correct, and if there's a better way of making this measurement?

Also, if you opt to use 3xAAA, would you solder wires from the AAA battery holder directly to the coin cell contacts? Or is there a better way I'm not seeing?

Thank you.
Jason

2

I have never heard of an ucurrent reader - the one i have is a simple frontend for your multimeter/scope which is the readout.

The few mA your circuit will use won't damage the uCurrent. What is warned about is something that may use 100's of mAmps or even several Amps which will damage the unit.

// Per.

3

The way I use to do this is to connect a switch in the supply and the multimeter in uA range
across the switch (which is normally closed). When the device is in sleep mode I open the switch
so the current goes through the meter.

4

Why not ask this question on the eevblog forum?
New people are welcome, and there is a beginner's section for just this sort of question.