How do you get the resistance value from a calibrated Wheatstone bridge circuit? I want to build a Wheatstone bridge to get the resistance of a pressure sensor. The unknown resistance in the Wheatstone bridge is the pressure sensor. I know that you can't use the connected multimeter in the Wheatstone bridge to get the resistance of the pressure sensor because the resistance here is very small to get an actual value, so you must use the Voltage parameter instead and get the resistance value somehow from that. You can't use the V=R/I equation because you cannot use the current parameter as well. So how is it that one can get the Resistance from the output Voltage parameter in the Wheatstone bridge?

  • $\begingroup$ Are you asking how to do the circuit analysis, or do you want some sort of handbook equation given known values in the bridge? $\endgroup$
    – TimWescott
    Commented May 12 at 15:57
  • $\begingroup$ More like a handbook equation. I need to know what would be a simple way to get resistance from voltage measurements after each step adding the pressure onto the sensor. My goal is to get a ΔR/R versus pressure change for this pressure sensor but getting ΔR and R I'm not so sure. $\endgroup$ Commented May 12 at 16:05
  • $\begingroup$ @Acrobatic-Ad-168 think about this, the left and right halves of the bridge are isolated from each other $\endgroup$
    – jsotola
    Commented May 12 at 17:30
  • $\begingroup$ The purpose of the bridge circuit, is that you don't have to measure ΔR/R, since measuring that ratio requires high dynamic range. Instead you'll get a small voltage that's approximately proportional to ΔR itself. Since building an amplifier with the necessary voltage gain is easier. Thus the calibration is in ΔV/V_excitation , rather than ΔR/R. Moreover, practical calibrated bridge elements have extra resistances added to trim balance (zero), and sometimes also to compensate tempco ... $\endgroup$
    – Pete W
    Commented May 15 at 2:10
  • $\begingroup$ could you share references to the above comment? $\endgroup$ Commented May 17 at 19:31


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