I recently bought a 20 pack of lm324s (quad op amp ic), and wanted to test them so I know they work before I put them in my projects. So I decided to build this circuit which test each one, then by probing the final out put, I know if they are all working. Each one has a gain of 2, and the square wave is generated by a 555 timer in a stable mode in my case (represented by the square wave generator in the circuit, but a function generator using any signal can be used), in my test circuit I used the voltage divider to step the the square wave to a smaller one that outputs voltages lower than the 555 can operate at to be amplified by the op amps, not to exceed the power supply voltage and cause clipping.
