Needs no manual operation for switching ON and OFF.  When there is a need of light it automatically switches ON. When darkness rises to a certain level then sensor circuit gets activated and switches ON .  when there is other source of light i.e. daytime, the street light gets OFF. The sensitiveness of the street light can also be adjusted. 

3. Electrical Engineering Department
CECOS University of I.T & Emerging Sciences Hayatabad,
Peshawar
Dark activator
Lamp--------------------------------------------------------------------------------------
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PREPARED BY :
JALAL AHMED

4. CONTENTS
1. Introduction
2. Why we need it
3. Required Components
4. Circuit diagram
5. Application

6. Introduction…………
 Needs no manual operation for switching ON and
OFF.
 When there is a need of light it automatically
switches ON. When darkness rises to a certain
level then sensor circuit gets activated and
switches ON .
 when there is other source of light i.e. daytime,
the street light gets OFF.
 The sensitiveness of the street light can also be
adjusted.

7. Why we need it…..
 To save energy
 To save power
 To save economy
 To reduce the human efforts
 To make system Automaticly

8. Required Components……
 Bread board
 CD 4049 Ic
 LDR
 Led (of any colour )
 Buzzer
 Resistors ( 220 ohm )
 9v battery

9. Circuit diagram………
Note:
LDR
Resistance
low when
light fall
upon it.
And high
when no
light fall
upon it.

10. Applications……
 Used in street
lights
 To reduce road
accident.

11. Continued……..
 To save human resourses
 Cost effective