LM324 is a 14pin IC consisting of four independent operational amplifiers (op-amps) compensated in a single package. Op-amps are high gain electronic voltage amplifier with differential input and, usually, a single-ended output. The output voltage is many times higher than the voltage difference between input terminals of an op-amp.
These op-amps are operated by a single power supply LM324 and need for a dual supply is eliminated. They can be used as amplifiers, comparators, oscillators, rectifiers etc. The conventional op-amp applications can be more easily implemented with LM324.
Pin Description:
 Pin No |  Function |  Name |
1 | Output of 1st comparator | Â Â Â Â Output 1 |
2 | Inverting input of 1st comparator | Input 1- |
3 | Non-inverting input of 1st comparator | Input 1+ |
4 | Supply voltage; 5V (up to 32V) | Vcc |
5 | Non-inverting input of 2nd comparator | Input 2+ |
6 | Inverting input of 2nd comparator | Input 2- |
7 | Output of 2nd comparator | Output 2 |
8 | Output of 3rd comparator | Output 3 |
9 | Inverting input of 3rd comparator | Input 3- |
10 | Non-inverting input of 3rd comparator | Input 3+ |
11 | Ground (0V) | Ground |
12 | Non-inverting input of 4th comparator | Input 4+ |
13 | Inverting input of 4th comparator | Input 4- |
14 | Output of 4th comparator | Output 4 |