Draw a circuit diagram of a full-wave rectifier using p-n junction diodes. Explain its working and show the input-output waveforms.
Show Hint
Uses both half cycles
Output frequency doubles
Can be centre-tapped or bridge type
Solution and Explanation
Concept: A full-wave rectifier converts both halves of an AC input into pulsating DC output using p–n junction diodes. It provides higher efficiency than a half-wave rectifier.
Circuit Diagram (Centre-tapped full-wave rectifier): Components:
Centre-tapped transformer
Two diodes \( D_1, D_2 \)
Load resistor \( R_L \)
Connections:
Anodes of diodes connected to the ends of secondary winding
Cathodes joined together and connected to load
Centre tap connected to other end of load
Working: Positive half cycle:
Upper end of secondary becomes positive
Diode \( D_1 \) forward biased → conducts
Diode \( D_2 \) reverse biased → off
Current flows through \( R_L \) in one direction
Negative half cycle:
Lower end of secondary becomes positive
\( D_2 \) conducts, \( D_1 \) off
Current again flows through load in same direction
Thus, both halves of AC are rectified → full-wave rectification. Input–Output Waveforms: Input waveform:
Sinusoidal AC wave
Positive and negative halves symmetric
Output waveform:
Both halves appear positive
Pulsating DC with double frequency of input
Graph description:
Input: sine wave about zero axis
Output: series of positive humps (no negative portion)
Key Features:
Output frequency = \( 2f \)
Higher efficiency than half-wave rectifier
Less ripple
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