Here is complete specification of transducer, with all parameters. Point is that the transducer gives 2.524V at 0A. I have to do some limitations, and it would be much easier when it would be 0V at 0A, and of course 5V at maximum current (3A), which is not satisfied, because transducer gives 4,627V at I=20A, so i can only operate with about 0.212V... If using simple voltage subtractor (diferential amplifier) the CMRR gets high, so at 0A have 0,6V. I tried R2 adjustments, but it affects only about 0.1V...
Of course, as i wrote before, when i connect in amp to indipendent regulated voltage source - no problem...
2.5V is supplied from voltage devider, 10V devided by 4700Ohm and resistance from potentiometer (about 17KOhm)...
Now i have a new problem which is same type - when trying to gain up the signal from voltage devider 21V/0.1V and then 0.1V to 5V with ordinary opamp gain is ok and is 10. In second case, when the voltage from shunt resistor (0.05 Ohm * 3 A = 0.15 V) is being gained to 5V, can't get more than 3V??????
Does this have something to do with matching source (shunt res as voltage source) and load (opamp) impedance? If does, how can it be achived?