Hi everybody I'm a newbie and working on LM324 to learn Op-Amp. this is my circuit: http://img4.uplood.fr/free/qx3o_20150425_172843.jpg [Broken] One of the resistors is 217ohm and another 978ohm. then the gain should be 4.50691 as you can see. so far so good. I know this is for ideal Op-Amp. I applied 0.15v to the input and got 0.94v in the output. then the gain is 6.26667. again I applied 0.35v to the input and got 2.03v then gain should be 5.8!? again I applied 1.86v and got 10.31 then the gain is 5.54301! holy crap! why isn't the gain stable? because of input offset voltage? How can I stabilize it?