Question

With the help of a circuit diagram, explain the use of a p-n junction diode as a full-wave rectifier. Draw the input and output waveforms.

Accepted Answer

P-n junction diodes can be used to make a full-wave rectifier:

The a.c input signal is fed to the primary (P) coil of the transformer. The p-region of both the diodes $D_{1}$ and $D_{2}$ are connected to two ends of secondary coil (S). The load resistance ( $R_{L}$ ) across which output voltage is obtained is connected between the common point of n-regions of diodes and a central topping of the secondary coil.

When the positive half cycle of input A.C signal flows through the primary coil, induced emf is set up in the secondary coil due to mutual induction. The direction of induced emf is such that the upper end of secondary coil becomes positive while lower end becomes negative. Thus, $D_{1}$ diode is forward biased and $D_{2}$ is reverse biased. So, current through $D_{1}$ flows through circuit in a direction shown. During negative half cycle of input a.c signal, diode $D_{1}$ is reverse biased and $D_{2}$ is forward biased. The current due to $D_{2}$ flows through circuit in a direction shown. Since, both the halves of input a.c (wave) are rectified, so the junction diode is called Full-wave rectifier.

With the help of a circuit diagram, explain the use of a p-n junction diode as a full-wave rectifier. Draw the input and output waveforms.

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