Power Amplifier Using Operational Amplifier
Électronique / Electronic
Now we're going to produce a loud sound by combining the operational amplifier with two transistors. After you complete the wiring, set the switch to position ON to turn on the power.
When you press the key you hear a loud sound from the speaker. The signal source for this sound is a capacitor-resistor oscillator.
The operational amplifier acts as an inverting amplifier, and transistors Q2 and Q3 cause the speaker to produce the sound. This circuit is called a single ended push-pull circuit (SEPP). You have learned about push-pull circuits. Single ended means the circuit has only one output. Most amplifiers have a second output that is connected to the negative ( - ) side of the battery.