It gives me a change from 120 ohms to 120.3 - 120.4 ohms change

With 5V on the bridge and three 120 ohm bridge resistors (which give the maximum voltage change with change is resistance) the bridge voltage change is only about 4mV, so you will need a high-gain, low-drift amplifier to get a decent output signal.

 

With 5V on the bridge and three 120 ohm bridge resistors (which give the maximum voltage change with change is resistance) the bridge voltage change is only about 4mV, so you will need a high-gain, low-drift amplifier to get a decent output signal.

@crutschow I actually use two 1k ohm resistors and one 120 ohm resistance along with the strain gauge. So does this setup too give a low voltage? If so, can you suggest me a good Op-Amp?

 

hi,
The LM358 is configured as a Differential amplifier, see attached link.

The 3 resistors and the strain gauge [R2 in that circuit] form a quarter Wheatstone bridge.
The simulation steps the value of R2 [strain gauge] through a small range of resistance values.
E

https://www.electronicshub.org/differential-amplifier/

Thanks @ericgibbs , will sure simulate the given circuit and try out implementing it practically!

 

Hello @bassbindevil , can you mention the series of the INA InAmp which you used?

INA121P, $7.41 Canadian at the time. The price seemed very low compared with some Analog Devices instrumentation amps I'd used in the past, and was negligible compared to the total cost of the project.