Load Cell Amplification INA125 Problems

Discussion in 'The Projects Forum' started by Tommyvdp, Oct 25, 2014.

  1. Tommyvdp

    Thread Starter New Member

    Oct 24, 2014
    2
    0
    Hi,
    I am trying to read an amplified load cell signal from the load cell SBO-2K (link below). See the attached schematic.

    http://www.transducertechniques.com/sbo-load-cell.aspx

    I am using the INA125 amplifier from TI:

    http://www.ti.com/lit/ds/symlink/ina125.pdf

    I am unable to get any feedback from the load cell at all. When it is plugged in it reads about 100mA, and when disconnected about 4.1 V, but it never changes, even though I have verified that the load cell is being excited and responding as expected (changes a few mV when I press on it). The amplification should set the output to about 0-1V from the 0-30mV signal from the load cell, but like I said, I get no response at all in the output.

    Any help would be greatly appreciated. I am not an expert, so feel free to tell me how wrong this circuit is! I just tried to follow the datasheet.
    Thank you,
    Tom
     
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,503
    380
    hi tommy,
    The pins 10 and 11 of the INA125 are connected to [analog] , what does that mean .?

    The INA125 connections seem to be incorrect.
    E
    EDIT :
    This image shows the connections for a similar project using a single voltage supply
     
  3. Tommyvdp

    Thread Starter New Member

    Oct 24, 2014
    2
    0
    Hi,
    See page 10 of the datasheet, 10 and 11 are connected as the voltage output, that is my Analog signal to a microcontroller.
    The unit excites the load cell, the cell responds properly, but there is just no amplification or change in the output voltage when the load cell voltage changes. Do you have a more specific suggestion for what is connected incorrectly?
    Thank you,
    Tom
     
  4. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,503
    380
    hi,
    Is your load cell connected as shown in this image.? also have you tried the circuit as this image.?

    E
     
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