I am trying to amplify the I/P voltage of 0.001-0.133 using opamp 741The circuit in #14 has issues. Any input offset voltage and/or bias current errors will be multiplied by the gain of the circuit.
To the TS:
What power supply voltages are available for the opamp?
What is the frequency range of the input signal?
What do you mean by "not able to get constant gain"? What gain does your circuit produce? In what way is the gain changing?
Please post your original schematic. While the 741 is not very good by today standards, there is no reason why its gain should vary in your application. Maybe we should solve the problem with your circuit before changing it to something else you don't understand.
ak
I am biasing with 12v power supply