Chapter -1

 

 Amplifiers

1. Explain the purpose and importance of transistor biasing. (3 Marks)

• Definition: Applying proper DC voltages to ensure the transistor operates in the active region.

• Purpose: * To produce distortion-free output.

  • To ensure a stable output and maintain thermal stability.

  • To control the amplifier gain.

2. Compare Voltage Amplifiers and Power Amplifiers. (4 Marks)

• Voltage Amplifier: Increases the signal's voltage level; used as a small-signal/driver amplifier; utilizes RC coupling and high output impedance.

• Power Amplifier: Increases the signal's power level; used as a large-signal/output amplifier; utilizes transformer coupling and low output impedance; requires high-power transistors with heat sinks.

3. Describe the Public Address (PA) System using a block diagram. (4 Marks)

• Microphone: Converts sound waves into audio (electrical) signals.

• Mixer: Combines and balances multiple audio input signals.

• Voltage & Power Amplifiers: Successively increase the voltage and power levels of the signal.

• Loudspeaker: Converts the final amplified electrical signals back into sound waves.