1.
Under the Supervision
Of
Md. Ashraful Islam Jewel
Lecturer, Department of CSE
Submitted
by
Md. Mahfuzur Rahman 201130496
Dept. of Computer Science and Engineering
Asian University of Bangladesh

2.
 Reducing the wastage of power
 Reducing physical efforts
 Improve the system in our daily life

3.
 simple and powerful device, which uses
Transistor (BC547 NPN)
 switches ON lights (LED) when the light (i.e. day
light) decreases
 switches OFF lights when light falls on LDR

4.
 Transistor BC547
 LDR (Light Dependence Resistor)
 Resistor
 LED

5.
Transistor BC547:
 has an emitter terminal, a base terminal and a
collector terminal
 current flowing from the base to the emitter
controls the collector current

6.
LDR
 an electronic component whose resistance decreases
with increasing incident light intensity
 used in a potential divider setup with a second regular
resistor
Resistor
 resist the flow of current across the resistor device
 adjustable resistors are refers to as potentiometers

7.
 Light falls on LDR, it shows its minimum
resistance and voltage drops across LDR less
than VBE of Transistor Q1.
 So, no current will go from the collector to the
emitter and transistor remains turn off.

8.
 No light falls on LDR, it shows its maximum
resistance and voltage drops across LDR greater
than VBE of Transistor Q1.
 Now the transistor enters into ON state and at the
output side Ic current will flow through the LED.
So, the LED is ON

9.
 Energy savings
 Low cost
 Safety and Security
 Reducing physical efforts

10.
 It has a limitation of power
 Light turns on when shadow falls on LDR
 LED is a low voltage device

11.
 By using same concept we can modify this project
for commercial use
 It is possible to make the project appropriate for
high voltage of power

12.
Question ?