LM324 is a series having low cost and having quad operational amplifiers. These amplifiers have true differential inputs. When concerning single supply applications, this type is more beneficial than the standard operational amplifiers. These can work at the voltage range of 3V to 32V. The current is also sufficient. Some of its features includes protection from short circuit, low input biased current, internally compensated, four amplifiers come in a package, industry standard pin-points, there is a common mode range that extents to the negative terminal, and many other exciting features. You can download LM324 DATASHEET from the link that is given above.