Question

With a neat circuit diagram, explain the working of a full-wave rectifier. Draw the input and output voltage waveforms.

Answer 1

A full-wave rectifier is a device or circuit that rectifies both half of each alternating voltage cycle.

Electric circuit: A transformer with a centre-tapped secondary coil (S₁S₂) and a primary coil (P₁P₂) receives the alternating voltage that has to be rectified across it. The two p-regions of two junction diodes D₁ and D₂, respectively, are linked to the secondary terminals S₁ and S₂. The ground is connected to the centre-tap T. Connected to both the ground and common n-regions is the load resistance R_L.

Full-wave rectifier circuit

Terminal S1 of the secondary is positive and S₂ is negative with respect to ground (the centre-tap T) throughout the one-half cycle of the input. Diode D₂ is reverse biased and does not conduct during this half cycle, whereas diode D₁ is forward biased and conducts. The direction in that current I_L travels through R_L is indicated.

Voltage waveforms for a full-wave rectifier (a) input (b) output

S₁ turns negative with respect to T and S₂ turns positive during the subsequent half-cycle of the input voltage. Sending a current I_L through R_L is now conducted in the same manner as before by diode D₂. D₁ doesn't conduct anymore. As a result, whether the input is received in half or in its entirety, the current through R_L flows in the same direction, or in a unidirectional manner. We refer to this as full-wave rectification. The output voltage is fixed in polarity and fluctuates between a maximum value and zero on a time-dependent basis. The input and output voltage waveforms are displayed in Figure. A full-wave rectifier's pulsating dc output voltage is twice as often as its ac input.