THIS IS COMPELTE VARIABLE POWER SUPPLY PROJECT, HELP YOU YOU TO UNDERSTAND. WE DESIGNED THE CIRCUIT ON PROTEUS AND ITS PICTURE IS IN PROTEUS.IT WILL GIVE YOU BOTH POSITIVE AND NEGATIVE VOLTAGE.

1. ELECTRONIC CIRCUIT DESIGN-I
INTERNATIONAL ISLAMIC UNIVERSITY,
ISLAMABAD
DEPARTMENT OF ELECTRONIC
ENGINEERING
FACULTY OF ENGINEERING AND TECHNOLOGY
Introduction:
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 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.
Hafiz Shahbaz Ali 1395-FET/BSEE/F10
Hamza Tahir 1340-FET/BSEE/F10
Muhammad Arslan 1360-FET/BSEE/F10

2. ELECTRONIC CIRCUIT DESIGN-I
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:
AC sourse(220V, 50Hz)
Step down Rectified
voltage(12x2V, 1A) output
Regulated Filtered
DC output
output output
Hafiz Shahbaz Ali 1395-FET/BSEE/F10
Hamza Tahir 1340-FET/BSEE/F10
Muhammad Arslan 1360-FET/BSEE/F10

3. ELECTRONIC CIRCUIT DESIGN-I
Circuit Diagram:
Hafiz Shahbaz Ali 1395-FET/BSEE/F10
Hamza Tahir 1340-FET/BSEE/F10
Muhammad Arslan 1360-FET/BSEE/F10

4. ELECTRONIC CIRCUIT DESIGN-I
Component:
Sr Components Name Quantity Rate Description
No (Rs)
1 Diode (1N4007) 4 1x4=4 VRB =1000V,IF=1A
2 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 1000 F,50V ,use to filter
the rectified AC
8 Resistor 4 4x1/4=1 100Ω
9 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/F10
Hamza Tahir 1340-FET/BSEE/F10
Muhammad Arslan 1360-FET/BSEE/F10

5. 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/F10
Hamza Tahir 1340-FET/BSEE/F10
Muhammad Arslan 1360-FET/BSEE/F10