If you change in this circuit the 741 opamp with LM741CN opamp the circuit doesn't function normal (at the output some kV results... I get results that are bigger then my dc supply can someone help me out?)
The opamp model with incorrect results must not have the output voltage clamped to the positive and negative rails (through diodes). I am not too familiar with MultiSim ... is it possible for you to view the model (netlist) of the subcircuit for the malfunctioning opamp. If you can post that model, I might be able to point out where the problem is originating from.