very simple and clear presentation of bridge rectifier and very helpful for the student of engineering .

1. The Bridge
Rectifier
Prof Vishnu Narayan Saxena
Contact at 09584932217
Email at
vishnunarayan.saxena@gmail.com

2. CONSTRUCTION: Fig (a) show the circuit diagram of full wave bridge
type rectifier it consists of a Step down transformer , four diode D1,D2,
D3, and D4 and a load resistance connected as shown in fig.
The A.C. Voltage is first applied to the primary of transformer which is step
down with the help of step down transformer and applied to the secondary
of step down transformer

3. During Positive half cycle of applied voltage
Point A becomes at Positive potential(+) whereas Point B will be at negative potential(-).
So diode D1 and Diode D3 becomes forward bias and behaves like a closed switch
Whereas Diode D2 and D4 becomes in reverse bias and behaves like an open switch
Fig (b) Equivalent circuit of full wave rectifier During positive half cycle

4. So Current will start to flow from Point Capital A through diode D1 to
the Point small a through Load resistance RL to Point small b through
Diode D3 and finally reaches to Point Capital B.
Fig ( c ) Shows the direction of current through the load resistance RL
A-------D1-------a------RL------b------D3--------B
In this way The Direction of current through the load RL is from
Small a to Small b.

5. During negative half cycle
Point A will be at Negative Potential (-) Whereas Point B will be at Positive
Potential
So Diode D1 and D3 Comes in Reverse Bias and behaves Like an Open Switch
Whereas Diode D2 and D4 comes in forward bias and behaves like a closed
switch
Fig( d) Equivalent Circuit diagram during negative half cycle

6. So During negative half cycle the current will start to flow from point capital B
Then through Diode D2 to point small a through load resistance RL to Point
small b to Diode D4 and finally reaches to Point Capital A
Fig ( d ) Shows the direction of current through the load resistance RL
B-------D2-------a------RL------b------D4--------A
In this way again the direction of current through the load is from small a
to small b.

7. So we saw that for positive half cycle as well as for negative half cycle
the direction of current through the load is same from Small a to small b
So the Voltage which will develop across the load will be D.C.
In this way the full wave rectifier convert both cycle of of an A.C. Voltage
into D.C.