Question

Draw a circuit diagram of a full-wave rectifier using p-n junction diodes. Explain its working and show the input-output waveforms.

Hint:

Full-wave rectifier facts:

Uses both half cycles
Output frequency doubles
Can be centre-tapped or bridge type

Answer 1

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