1. Lecture – 4 Full wave rectifier
Mathematical Exercise of Full wave rectifier.
Special purpose Diode ( Zener Diode )
Mathematical exercise of Zener Diode.

2. Full- Wave Rectifier ( Circuit Details )

3. Full wave Rectifier ( cont. )

4. Full-Wave Rectifier (Cont.)
Advantages:
(i) The need for centre-tapped transformer is eliminated.
(ii) The output is twice that of the centre-tap circuit for the same secondary voltage.
(iii) The PIV is one-half that of the centre-tap circuit (for same d.c. output).
Disadvantages:
(i) It requires four diodes.
(ii) As during each half-cycle of a.c. input two diodes that conduct are in series, therefore, voltage drop in the internal resistance of the rectifying unit will be twice as great as in the centre tap circuit. This is objectionable when secondary voltage is small.

5. Question : A full-wave rectifier uses two diodes, the internal resistance of each diode may be assumed constant at 20Ω. The transformer r.m.s. secondary voltage from centre tap to each end of secondary is 50 V and load resistance is 980 Ω. Find :
(i) the mean load current (ii) the r.m.s. value of load current

6. Special Purpose Diode ( Zener Diode )
Definition:
A properly doped crystal diode which has a sharp breakdown voltage is known as a zener diode.

7. Zener Diode ( Cont. ) Characteristics of Zener Diode:
(i) A zener diode is like an ordinary diode except that it is properly doped so as to have a sharp breakdown voltage.
(ii) A zener diode is always reverse connected i.e. it is always reverse biased.
(iii) A zener diode has sharp breakdown voltage, called zener voltage Vz.

8. Question: For the circuit shown in Fig .(i), find :
(i) the output voltage (ii) the voltage drop across series resistance
(iii) the current through zener diode.

9. Thank You