Rectifier is an electronic device which converts alternating current (AC) into direct pulsating current (DC). Rectifiers are of two types, namely, Half wave rectifier and Full wave rectifier.

Full Wave Rectifier :-

A Full wave rectifier is a circuit which allows a unidirectional current to flow through the load during the entire period of input voltage cycle. Circuit for full wave rectifier goes like this,

In above circuit diagram, D1 and D2 are the two diodes and R to the base L (RL) is load resistor.

Working of Full wave Rectifier :-

1. During the positive input half cycle of secondary voltage, diode D1 is forward biased and diode D2 is reverse biased.
2. As a result, diode D1 conducts some current whereas diode D2 does not conduct i.e. it is OFF
3. The conventional current flows through the diode D1, load RL and the upper half of the circuit diagram, i.e. path A-D1-RL-C-A.
4. During the negative input half cycle of secondary voltage, diode D2 is forward biased and diode D1 is reverse biased.
5. As a result, diode D2 conducts some current whereas diode D1 does not conduct any current.
6. Thus, the conventional current flows through diode D2, load resistor RL and the lower part of th circuit i.e. follows path of B-D2-RL-C-B.
7. The output waveforms are shown in the above figure.
8. It may also be noted that current through load RL flows towards the same direction during both positive and negative half cycles of AC input voltage.
9. Therefore, output voltage developed across load RL is full wave rectified.

Advantages :-

1. The DC output voltage and DC load current values are twice than those of the half wave rectifier.
2. The Ripple factor is much less (0.482) than that of half wave rectifier.
3. The rectification efficiency is twice than that of half wave rectifier. For full wave rectifier, maximum  rectification efficiency is 81.2% and that for half wave rectifier is 40.6%

Disadvantages:-

1. Output voltage is half of the secondary voltage.
2. Peak inverse voltage of diode is twice of the diode used in half wave rectifier. So, diodes used must have high peak inverse voltages.
3. It is expensive to manufacture a center tapped transformer.