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Wednesday, October 5, 2011

FULL-WAVE RECTIFIER


FULL-WAVE RECTIFIER
AIM:-To find the Ripple factor and regulation of a Full-wave Rectifier with and without filter.
APPARATUS:-
Experimental Board
Transformer (6-0-6v).
P-n Diodes, (lN4007) ---2 No’s
Multimeters                  –2No’s
Filter Capacitor (100μF/25v) -
Connecting Wires
Load resistor, 1KΩ

THEORY:-
              The circuit of a center-tapped full wave rectifier uses two diodes D1&D2. During positive half cycle of secondary voltage (input voltage), the diode D1 is forward biased and D2is reverse biased.
The diode D1 conducts and current flows through load resistor RL. During negative half cycle, diode
D2 becomes forward biased and D1 reverse biased. Now, D2 conducts and current flows through the load resistor RL in the same direction. There is a continuous current flow through the load resistor RL, during both the half cycles and will get unidirectional current as show in the model graph. The difference between full wave and half wave rectification is that a full wave rectifier allows unidirectional (one way) current to the load during the entire 360 degrees of the input signal and half-wave rectifier allows this only during one half cycle (180 degree).





CIRCUIT DIAGRAM:-

                   
PROCEDURE:

1.        Connections are made as per the circuit diagram.
2.        Connect the ac mains to the primary side of the transformer and the secondary side to the rectifier.
3.        Measure the ac voltage at the input side of the rectifier.
4.        Measure both ac and dc voltages at the output side the rectifier.
5.        Find the theoretical value of the dc voltage by using the formula Vdc=2Vm/П
6.        Connect the filter capacitor across the load resistor and measure the values of Vac and Vdc at the output.
7.        The theoretical values of Ripple factors with and without capacitor are calculated.
8.        From the values of Vac and Vdc practical values of Ripple factors are calculated. The practical values are compared with theoretical values.


THEORITICAL CALCULATIONS:-


                                  Vrms = Vm/ √2
                                  Vm =Vrms√2
                                  Vdc=2Vm/П
(i)Without filter:
                             Ripple factor, r = √ ( Vrms/ Vdc )2 -1 = 0.482
(ii)With filter:                                                                

                  Ripple factor, r = 1/ (4√3 f C RL)         where    f =50Hz
                                                                                             C =100µF
                                                                                             RL=1KΩ
  PRACTICAL CALCULATIONS:                                       

   Without filter:-
                                      Vac=
                                      Vdc=
                          Ripple factor, r=Vac/Vdc
    With filters:-
                                               Vac=
                                              Vdc=
                       Ripple factor=Vac/Vdc

    Without Filter:
USING DMM
Vac(v)
Vdc(v)
r= Vac/ Vdc






With Filter

USING DMM
Vac(v)
Vdc(v)
r= Vac/ Vdc




Without Filter            
                      
Vrms = Vm/ √2     ,   Vdc=2Vm/П ,   Vac=√( Vrms2- Vdc 2)   
        

USING CRO
Vm(v)
Vac(v)
Vdc(v)
r= Vac/ Vdc






With Filter

USINGCRO
V1(V)
V2(V)
    Vdc= (V1+V2)/2
Vac=
(V1- V2)/2√3
r=
Vac/ Vdc






PRECAUTIONS:

1.    The primary and secondary side of the transformer should be carefully identified
2.    The polarities of all the diodes should be carefully identified.

RESULT:-
The ripple factor of the Full-wave rectifier (with filter and without filter) is calculated.

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