This pulsating voltage cannot be used 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 (η) is the ratio of the output DC power to the AC input power supplied to the circuit . Its value for half wave rectifier is .
%. If the direction of the diode is reversed, the negative half of the AC signal is passed through and the positive half is blocked. Note ii) Full wave rectifier The positive and negative half cycles of the AC input signal are rectified in this circuit and hence it is called the full wave rectifier. The circuit is shown in Figure .
(a). It consists of two p-n junction diodes, a centre tap transformer and a load resistor R L . The centre is usually taken as the ground or zero voltage reference point. With the help of the centre tap transformer, each diode rectifies one half of the total secondary voltage.
During positive half cycle When the positive half cycle of the AC input signal passes through the circuit, terminal M is positive, C is at zero potential and N is at negative potential. This forward biases diode D and reverse biases diode D . Hence, being forward biased, diode D conducts and current flows along the path MD ABC During negative half cycle When the negative half cycle of the AC input signal passes through the circuit, terminal N becomes positive, C is at zero 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 and the waveform of the output voltage is shown in Figure . (b). 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