Strain gauge bridge amps

Help & Support Robot Parts
1

Two questions for the experts (I am clearly not one):

  1. I have some ONL-38 bridge amps for use with strain gauges. The units I inherited have the 1 kHz low pass filter. I want to change the cutoff frequency to maybe 5 kHz. Should I attempt to change the surface mount resistors and capacitors, is it better to order new amps with the correct components?

  2. It would be nice to have the strain gauge readings be linear; i.e., to use a nulling bridge amp. Is there a Robot Shop part for that? If not, any suggestions?

4

Hi,

Thank you for posting on the RobotShop’s Community and sorry for the delay.

  1. Indeed, the Load Cell Shield comes with a low-pass 2nd order Bessel filter with a cut-off frequency of 1KHz. The filter can be adjusted by replacing the surface mount resistor and/or capacitor values for a specific required frequency. R1_1, R1_2, C1_1 and C1_2 are related to channel one (First number of component indicates the channel number it is associated with). Component names R2_1, R2_2, C2_1 and C2_2 related to channel 2. You can use the freeware FilterLab to calculate the required values of the filter for a cut-off frequency of 5KHz.
  2. We unfortunately don’t offer such a part. Please note that the Load Cell shield, has also two onboard potentiometers (one for each channel), to set the reference voltage and offset the output signal if need be. Please also note that we offer this Strain Gauge Module
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