Power amplifier using op amplifier LM324
Electronic

We're now going to produce a loud sound by combining the op amplifier and two transistors. The schematic shows you that the signal source is a phase-shifting CR oscillator.

The op amplifier is used as an inverting amplifier, Q2 and Q3 cause the speaker to make a loud sound. This circuit is called an SEPP (Single Ended Push-Pull) circuit.

Turn power ON and press S1. You'll hear loud sound from the speaker.