ORCAD PSPICE : LM324 Help !! I am making a simulation of my project on Intercom using LM324 opamp as preamp and before Power amp ckt. But I am having trouble with that. I tried making an inverter using LM324 with pin 11 as ground. But this does not give correct result. Although the datasheet shows that pin 4 is +Vcc and pin 11 is GND. The tutorials I could find on internet used a negative supply at pin 11 though it should have been ground. Please help.