A cheap way to compare DC microamp readings in multimeters.

[camurgo]

Hi everyone,

I would like compare the accuracy of the readings of my multimeters in the DC microamp range. I would also like to accomplish this in the cheapest way possible.
To carry this out I assume I need some sort of adjustable electronic load (I have of one these, https://www.aliexpress.com/item/ATORCH-150W-Constant-Current-Electronic-Load-200V20A-Battery-Tester-Discharge-Capacity-Tester-meter-12V24V48V-Lead-acid/32821877897.html?spm=a2g0s.9042311.0.0.78854c4dKUizpX  and it works fine for the amp range) or current source, but I couldn't find one so far that goes below the miliamp range.

Does anyone have tips/suggestions to achieve this?  Thanks.

[ArthurDent]

You can compare one meter against the other to see how closely they agree but that tells you next to nothing about the accuracy of the meters, unless one is of known high accuracy. Also an electronic load like you've shown probably isn't that useful, especially for low level currents.

If you had a known accurate power supply voltage with a known accurate resistor you could check the known current accuracy of your meters. Without knowing 2 of the variables in the equation E=IR you can't accurately calculate the third. Also the R in the equation is the known accurate resistor plus the meter resistance.

[6PTsocket]

Hi everyone,

I would like compare the accuracy of the readings of my multimeters in the DC microamp range. I would also like to accomplish this in the cheapest way possible.
To carry this out I assume I need some sort of adjustable electronic load (I have of one these, https://www.aliexpress.com/item/ATORCH-150W-Constant-Current-Electronic-Load-200V20A-Battery-Tester-Discharge-Capacity-Tester-meter-12V24V48V-Lead-acid/32821877897.html?spm=a2g0s.9042311.0.0.78854c4dKUizpX  and it works fine for the amp range) or current source, but I couldn't find one so far that goes below the miliamp range.

Does anyone have tips/suggestions to achieve this?  Thanks.

What is your reference standard? If it is an accurate microammeter, put the meters in series, adjust current for mid scale and full scale readings on the reference meter and compare. If it is an accurate voltmeter, buy  a resistor to the accuracy you require and mesure voltage drop across the resistor. Ohms law will take it from there.  Select values that will be on the upper part of the ammeter range. Linearity is a factor. Meters can be dead on at one part of the range and off in another. There is no need for some super accurate source, as long as it is adjustable to get your meters to read on scale. Remember, these are microammeters so keep current limiting in mind.

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