measuring very small resistances

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I'm trying to figure out how to check the resistance of a load. It is very small, varying between 0.14 - 0.17 ohms depending on the temperature. The minimum delta that I should be able to detect reliably is 0.01 ohms. Is this feasible??

Last Edited: Thu. Oct 19, 2017 - 12:00 AM
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I suspect this Thread might get a better reply if a Moderator moved it to the General Electronics Sub-Forum.

 

JC

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Well, with a current of 1mA that's 10µV. You will need an amplifier with very low offset (chopper stabilized, probably).

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Put a few amps through it, you can produce enough voltage drop to get above the noise floor (the brute force way)!!...Or use better amplifiers, such as the mentioned chopper-stabilized that can go down to microvolt offsets, perhaps even use a synchronous approach to better reject noise.

 

Use kelvin metering connections to minimize the effect of the measuring leads  (one pair provides the signal, the other pair performs the measuring).  

 

If the load is already powered by something, things may be more complex, especially since the drive signal could be noisy or ill-suited for measuring purposes.

When in the dark remember-the future looks brighter than ever.

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Google silicon chip esr meter
Works a treat both for checking caps but also measuring low R like short circuits on pcbs etc.
There’s extensive discussion on the operation and other versions on the interwebs. The technique is uses is fiendishly simple.

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I found a solution, a 0.001 ohm current sense resistor in series with the resistance to be measured, and a component INA199 which is precision amp for just this purpose, 0.15 ohms becomes 2 volts with that sense resistor and 100x amplification. Thank you for ideas!