Wheatstone bridge

Discussion in 'The Projects Forum' started by dsp_redux, Mar 5, 2010.

  1. dsp_redux

    Thread Starter Active Member

    Apr 11, 2009
    Hi, I'd like to build a Wheatstone bridge to measure a resistance with precision. The thing is, all the examples I have seen are for Wheatstone bridges where you need to manually balance the bridge with a potentiometer. Since I'm "reading" the resistance (in fact a precision temperature probe) on a regular basis, I wanted to hook that bridge to an acquisition card (DAQ) to read the output voltage. Is it possible for the bridge to give me between 1V and 10V if the unknown resistor is from 24880 to 29860 ohms ?
    Last edited: Mar 5, 2010
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    With only one variable resistance, life might be simpler using a fixed resistor in series and a very stable voltage supply. Take the changing voltage at the junction between the two resistors and apply an op amp to span the desired offset and response.
  3. russ_hensel

    Well-Known Member

    Jan 11, 2009
    The idea of the bridge is to bring it into ballance. What you would end up with would not be a bridge really.
  4. DickCappels


    Aug 21, 2008
    Yes, it is possible to process the output of the bridge so that the output voltage will be between 1V and 10V when the resistance being measuerd varies from 24880 to 29860 Ohms.

    if you bridge is DC, and the output is already referenced to ground, so much the better.

    For the most part, its a matter of resistors and opamps.
  5. dsp_redux

    Thread Starter Active Member

    Apr 11, 2009
    DickCappels: Got it! I'll be using an AD623. Thx everyone.