Hey everyone,
I have built a small amplifier to run a strain gauge. Here is the circuit:
The problem I am having is that the piece of metal my strain gauge is mounted on does not deform very much and the change in output is very small. The INA131 has a built in gain of 100 and at that setting I can barely notice a difference in voltage, I added a variable resistor over terminal 1 and 8 to change the gain higher. The problem I am seeing is that since I have the 5v regulator in there I can't set the INA131 higher than 5v output.
I turned it up to about 3V output (G=1000ish, the strain gauge outputs about 3.5mV) at rest and added 150lbs of load, this gave me only 0.2V in change. I would like to see 1V of change for every 100lbs, as you can see I am nowhere near the gain setting needed and since I can't go past 5V I am stuck.
What do I do? Is there a way to shift my voltage back down to 0V so I can keep cranking the gain up? I probably need something closer to a gain of 10000.
I have built a small amplifier to run a strain gauge. Here is the circuit:
The problem I am having is that the piece of metal my strain gauge is mounted on does not deform very much and the change in output is very small. The INA131 has a built in gain of 100 and at that setting I can barely notice a difference in voltage, I added a variable resistor over terminal 1 and 8 to change the gain higher. The problem I am seeing is that since I have the 5v regulator in there I can't set the INA131 higher than 5v output.
I turned it up to about 3V output (G=1000ish, the strain gauge outputs about 3.5mV) at rest and added 150lbs of load, this gave me only 0.2V in change. I would like to see 1V of change for every 100lbs, as you can see I am nowhere near the gain setting needed and since I can't go past 5V I am stuck.
What do I do? Is there a way to shift my voltage back down to 0V so I can keep cranking the gain up? I probably need something closer to a gain of 10000.