Bridge Type Full wave Rectifier

 Bridge Type Full wave Rectifier



Above fig. shows a bridge rectifier, it is a commonly used circuit in power supplies.

It consists of four diodes connected forming as a bridge circuit.

The step down transformer lower the 230V/50Hz A.C. mains into desired value.

The secondary of the transformer drives the bridge circuit formed by diodes D1, D2, D3 and D4. The DC output is across RL.

Working:

During positive half cycle of input voltage (point A positive with respect to B), diodes D1, D2 conduct and the current flows through load resistance RL developing a voltage drop across it.The path of the current flow at this time is A D1RLD2B  as shown by the dotted line

During negative half cycle (point B positive with respect to point A) so, diode D3 , D4 conducts and the current flows through RL as shown.The path of the current flow at this time is B D3RLD4A  as shown by the in the circuit above.

 

This produces a voltage drop across RL similar to the positive half input.

Thus, rectified D.C. voltage is obtained across RL.

The D.C. output voltage across the load is given by,





–        Out of three rectifiers, Bridge type is the most preferred in power supplies.

–        Now a days, a block of four diodes embedded in a single unit is available as bridge wave rectifier, mostly used in power supplies.

–        It has four terminals as shown, two for A.C. input ant two for D.C. output. 

                                                          


–        Comparison of Rectifiers:

       

   7             Vdc output voltage                       Vm/π              2Vm/π                2Vm/π

               8              T.U.F.                                             0.287               0.693                  0.812

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