INA125 Amplifier on Quarter Bridge

Discussion in 'The Projects Forum' started by persian, Mar 28, 2010.

Thread Status:
Not open for further replies.
  1. persian

    Thread Starter New Member

    Mar 26, 2010
    12
    0
    Hi there,

    I am having a problem with my circuit.I am using the INA125 amplifier. I am using a single supply voltage about 12 v and using the voltage regulator to give me 5v on to a quarter bridge. I have been using a 10 ohm/25turn potentiometer as my strain gauge plus 340 fixed resistor. I have been checking that for each turn on the strain gauge the voltage should change in a certain amount.but my results are half off.

    calculation =((4.98*0.4*#of turns)/(2*(2*365+0.4*# of turns)))

    results after each turn starting from 0

    trial 1 trial 2 actual amount calculated
    0 0 0
    0.437 0.492 1.36006
    1.2 1.226 2.718632
    2.08 2.091 4.086433
    2.57 2.62 5.445599
    3.35 3.41 6.803279
    4.05 4.13 8.159476
    4.73 4.79 9.519476
    5.32 5.35 10.86743

    I set each potentiometer to 25 each so that r1 to r3 is 365 while the r4 is 370. I balance the circuit and then I turn the 10 ohm potentiometer set as 5.I am using 1000 gain. I am not using a load between 11 and 5 only because the voltmeter it self has resistance
     
Loading...
Thread Status:
Not open for further replies.