ELECTRONIC CIRCUIT DESIGN-I

INTERNATIONAL ISLAMIC UNIVERSITY, ISLAMABAD

DEPARTMENT OF ELECTRONIC ENGINEERING

FACULTY OF ENGINEERING AND TECHNOLOGY

Variable Power SupplyIntroduction:

Our project is the power supply of the trainer. It is capable of supplying constant as well as variable dual voltages to the user. It has efficiency to give current of 1A. It is small, simple, cheap and efficient circuit that is performing efficent functions. It cost 378Rs.

Working of the circuit :A main supply (220v,40Hz) is supplied directly to the center tapped transformer and transformer steps down it to about 24V.These voltages are rectified through the bridge rectifier which is at once after the transformer. Rectified signal is the continuous pulsating DC then capacitors filters the pulsating DC into

Hafiz Shahbaz Ali 1395-FET/BSEE/F10Hamza Tahir 1340-FET/BSEE/F10

Muhammad Arslan 1360-FET/BSEE/F10

ELECTRONIC CIRCUIT DESIGN-I

the smooth non pulsating DC (constant graph) .Now this DC is regulating by the IC’s.

ICLM317 regulates about 0 to 12V.IC LM337 regulates about 0 to -12V.So user can easily get the desired voltages from the output pins of the different regulators. In the circuit, we have placed the separate output pins for positive and negative voltage, and common ground pin of the whole

circuit is also available in our circuit.

Block Diagram:

Hafiz Shahbaz Ali 1395-FET/BSEE/F10Hamza Tahir 1340-FET/BSEE/F10

Muhammad Arslan 1360-FET/BSEE/F10

erTransfor

diode 4 Capacitor

317LMsOutput pin

AC sourse(220V, 50Hz)

Step down voltage(12x2V, 1A)DC output

Regulated output

Rectified output

Filtered output

ELECTRONIC CIRCUIT DESIGN-I

Circuit Diagram:

Hafiz Shahbaz Ali 1395-FET/BSEE/F10Hamza Tahir 1340-FET/BSEE/F10

Muhammad Arslan 1360-FET/BSEE/F10

ELECTRONIC CIRCUIT DESIGN-I

Component:Sr No

Components Name Quantity Rate(Rs)

Description

1 Diode (1N4007) 4 1x4=4 VRB =1000V,IF=1A2 Vero board 1 65 Use to make permanent

design using solding technique.

3 LM 317 1 20 1.5A,Adjustable positive voltage regulator

4 Potentiometer(5kΩ) 2 2x10=20 Use for changing the voltage

5 Transformer 1 145 12v step down with 1A current

6 Lm 337 1 45 1.5A,Adjustable negative voltage regulator

7 Capacitor 2 2x25=50 1000μF,50V ,use to filter the rectified AC

8 Resistor 4 4x1/4=1 100Ω9 Female connector 9 9x40/35=7.875≈8 From where we get the

DC voltage.

Total cost =378 Rs

Conclusion: In short, our circuit can serve as the variable as well as dual power supply for the user. If the user wants a particular value signal that is not available by the power supply then he will not go to the market to purchase another power supply , he can take help from the amplifier circuit available in our project circuit and can amplify the signal in the available range to do his work easily.

Hafiz Shahbaz Ali 1395-FET/BSEE/F10Hamza Tahir 1340-FET/BSEE/F10

Muhammad Arslan 1360-FET/BSEE/F10

ELECTRONIC CIRCUIT DESIGN-I

For example User wants 20vp.p but 10vp.p is available in the lab then our circuit can help the user.our circuit has ability to amplify the 10vp.p into the 20vp.p.User just apply 10vp.p as a input to the amplifier circuit and get 20vp.p on the output of the circuit.

Hafiz Shahbaz Ali 1395-FET/BSEE/F10Hamza Tahir 1340-FET/BSEE/F10

Muhammad Arslan 1360-FET/BSEE/F10