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Full wave Bridge rectification

BS P-III

Institute of Phsics

Full wave bridge rectification Objects of the experiment To understand the operation of full wave bridge rectifier.

Introduction In full wave rectification the output current flows in the same direction during both half cycles of the alternating input voltage. There are two methods to achieve the full wave rectifier. • Bridge full wave rectification. • Center tapped full wave rectification. A bridge rectifier makes use of four diodes in a bridge arrangement to achieve full-wave rectification as shown in figure 1. The bridge rectifier is the most commonly used full wave rectifier circuit for several reasons. 1. It does not require a center tapped transformer, and therefore can be coupled directly to the ac power line if desired. 2. Using a. transformer with the same secondary voltage produces a peak output voltage that is nearly double the voltage of the full wave center tapped rectifier. This results in a higher dc voltage from the supply. Function generator input

5

D3

D1 = RL

D4 8

1K

D2

Fig.1 A full wave bridge rectifier

Operation: When the input cycle is positive for bridge full wave rectification, diodes D1 and D2 are forward biased and conduct current as shown in fig 2 . At this time a voltage is developed across RL which look like the positive half of the input cycle. During this time diodes D3 and D4 are reverse biased. Function generator input

D3

D1

5

= D4 8

RL

1K

D2

Fig.2 Full wave bridge rectifier during positive half cycle

When input cycle is negative, the diodes D3 and D4 are forward biased as shown in figure 3 and conduct current in same direction through RL as during positive half cycle. During the negative half cycle, diodes D1 and D2 are reverse biased.

1

Full wave Bridge rectification

BS P-III

Institute of Phsics

D1

Function generator D3 5 input

= RL

D4

1K

8 D2

Fig.3 Full wave bridge rectifier during negetive half cycle

EQUIPMENT ■ Oscilloscope ■ Function generator COMPONENTS: ■ A bread board

■ Four diodes(IN 4007series)

■ 1K

resistor

■ A few connecting hard wires

PROCEDURE: 1. Setup the function generator to a suitable frequency and peak voltage. 2. Make the half wave circuit diagram as shown in fig 1. 3. Observe the rectified output at diffrent peak to peak voltge values. 4. Calculate the ripple factor in each case. 5. Observe the ripple on the Oscilloscope, using the feature of dc/ac coupling.

OBSERVATION TABLE: S.No.

Vin (p-p)

Vout (peak)

Vavg = Vp/

= Vp

2

Ripple factor

REVIEW QUESTIONS: 1. What is full wave Bridge rectification? 2. Which type of rectifier has high ripple factor? 3. In bridge rectifier, how many diodes are forward biased during one cycle?

FINAL CHECK LIST: • •

Clean your equipment/materials and workbenches before you leave. Return all equipment and materials to their proper storage area.