1. Lecture No# 4 Prepared by: Engr. Qurban Ali Memon
Incharge of Project Lab.

2. LAB EXPERIMENT NO # 04
To understand the operation of full wave center tapped rectification by using breadboard.
Components: 1. Bread board 2. two diodes (1N4001) 3. step down transformer 4. Load resistor (1kΩ) 5. Oscilloscope 6. Few hard wires.

3. Bread board: A breadboard is used to connect any circuit temporary.
The breadboard has many holes into which circuit components like IC and resistors can be inserted
Breadboard

4. Step-up transformers converts low voltage into high voltage.
A transformer is used to convert high voltage into low voltage or low to high.
Types of transformers:
1. Step-up:
Step-up transformers converts low voltage into high voltage.
2. Step-down:
Step-down transformers is used to convert low into high voltage.
Most electronic circuits operate on lower voltage than the AC line voltage.

5. Transformer

6. Oscilloscope:
An oscilloscope is an abbreviation Cathode ray Oscilloscope (CRO).
The oscilloscope is a versatile instrument.
The main function of Oscilloscope is used to measure the dc/ac voltage, dc/ac current and also we can check two or more waveforms on the screen.
We can observe the input and output on Oscilloscope . Oscilloscope is used to show the graphically signals on screen.
Oscilloscope:

7. Full wave rectification:
Full wave rectification is the process which converts ac input voltage into dc pulsating with two output pulses for each input cycle.
The full wave rectifier consist of two diodes and a load resistor .
Input

8. Operation:
During the positive half cycle of a.c input voltage, point P1 is positive and point P2 negative.
This makes the diode D1 is forward biased and diode D2 reverse biased.
Therefore D1 conducts the current and D2 does not conduct the current, so current will only flow across D1 through the load resistor and shows upper half cycle in fig. below
During the negative half cycle of a.c input voltage, point P2 is positive and point P1 negative.
This makes the diode D2 is forward biased and diode D2 reverse biased.
Therefore D2 conducts the current and D2 does not conduct the current, so current will only flow across D2 through the load resistor in upper half cycle.

9. D1 D2 D1 D2
Output of full wave
Input of full wave

12. Peak Inverse Voltage (PIV) of Centre-Tap Full Wave Rectifier
PIV is the maximum possible voltage across a diode during its reverse biased period. Let us analyze the PIV of the centre- tapped rectifier from the circuit diagram. During the first half or the positive half of the input ac supply, the diode D1 is positive and thus conducts and provided no resistance at all. Thus, the whole of voltage Vs developed in the upper-half of the ac supply is provided to the load resistance RLOAD. Similar is the case of diode D2 for the lower half of the transformer secondary.
Therefore, PIV of D2 = Vm + Vm = 2Vm
               PIV of D1 = 2Vm