Draw the circuit diagram of a half wave rectifier and explain its working.

Explanation

The half wave rectifier circuit. The circuit consists of a transformer, a p-n junction diode and a resistor. In a half wave rectifier circuit, either a positive half or the negative half of the AC input is passed through while the other half is blocked. Only one half of the input wave reaches the output. Therefore, it is called half wave rectifier. Here, a p-n junction diode acts as a rectifying diode.

During the positive half cycle:
When the positive half cycle of the ac input signal passes through the circuit, terminal A becomes positive with respect to terminal B. The diode is forward biased and hence it conducts. The current flows through the load resistor `R_L` and the AC voltage developed across `R_L` constitutes the output voltage `V_0` and the waveform of the diode current. During the negative half cycle: When the negative half cycle of the ac input signal passes through the circuit, terminal A is negative with respect to terminal B. Now the diode is reverse biased and does not conduct and hence no current passes through `R_L`. The reverse saturation current in a diode is negligible. Since there is no voltage drop across `R_L` the negative half cycle of ac supply is suppressed at the output.
The output of the half wave rectifier is not a steady de voltage but a pulsating wave. This pulsating voltage is not sufficient for electronic equipments. A constant or a steady voltage is required which can be obtained with the help of filter circuits and voltage regulator circuits. Efficiency `(eta)` is the ratio of the output dc power to the ac input power supplied to the circuit. Its value for half wave rectifier is 40.6 %