Full Wave Bridge rectifier each half cycle of input produce current pulses.As disadvantage of the center-tap full wave rectifier is that because only half of the secondary winding is used at anytime the transformer has to produce twice the voltage required. The problem does not arise if four diodes are connected as a bridge network.
If A is positive with respect to B during the first half cycle, D2 and D4 are forward biased and the current takes the path A,D2,R,D4,B. On the next half cycle when B is positive (with respect to A), D1 and D3 are conducting and the current follows the path B, D3, R, D1, A. The current through R is in the same direction during both half cycles of input and a varying DC output is obtained.
All four diodes are available in one package and the junction temperature of a diode must be kept low, therefore, in order to dissipate the heat associated with high current carrying rectifiers, they are mounted onto black painted aluminum sheet heat sinks.
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