Inverting amplifier LM324
We're now going to make an inverting amplifier using the op amplifier. The signal source is a phase-shifting CR oscillator using a transistor, which generates a sine wave.
In this project, we'll amplify the signal from this oscillator to activate the speaker. Gain A of the inverting amplifier is expressed by the following formula:
A = RB/RA
This means that the gain becomes greater if RB is increased or RA is decreased.
When you finish wiring up the equipment, turn power ON and see what happens when you press S1. You can hear a clear, high-pitched sound from the speaker. You can practice sending Morse code by pressing S1 intermittently.