trying 4 wire method on 2 wire RTD

Discussion in 'General Electronics Chat' started by, Jun 2, 2014.


    Thread Starter Member

    Feb 27, 2014
    I am trying to do 4 wire RTD measurement method on 2 wire RTD or thermistor.
    as in picture attached. (Zoom out picture, if not clear)

    AIN0 is channel used as current source.
    AN1 & AIN2 are differential channels across which measurement is done.
    R3 is used put measurement in common mode level.

    1. Question is when I use AIN0 as current source on power up, current will rush through capacitor across R1. (forget to mentioned its name in picture)

    Will it cause trouble in measurement?

    2. So can I do 4 wire measurement like this for 2 wire RTD or thermistor?
    • pic.pdf
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  2. Sensacell

    Well-Known Member

    Jun 19, 2012
    The differential output voltage across the RTD depends of the accuracy and stability of the driving current source, I do not understand the circuit as drawn?

    How does the output pin become a precision current source?