automatic street light project report

1. AUTOMATIC
STREET LIGHT
CIRCUIT
S U B M I T T E D B Y
T A R I Q K H A N ( 6 3 7 - 2 0 1 7 ) B S - E L
INDUS UNIVERSITY
University of Engineering , since and Technology

2. OVERVIEW OF PROJECT
 The main purpose of designing this project is to
prevent loss of current unnecessarily during day
time.
 During night the bulb will automatically glow .

3. ABSTRACT
 A street light that automatically switches ON when the
night falls and turns OFF when the sun rises.
 In fact we can use this circuit for implementing any type
of automatic night light.
 The circuit uses a LDR to sense the light .
 When there is light the resistance of LDR will be low.
So the voltage drop across LDR. And it keeps the
transistor ON. so the relay will be ON. The bulb will be
remain OFF.
 When night falls on LDR. the resistance of LDR Very
high.
 This makes transistor OFF. The relay
will be OFF and the bulb will be glow.

4. CIRCUIT DIAGRAM

5. COMPONENTS REQUIRED
 RELAY
 LIGHT DEPENDENT RESISTOR
 RESISTOR
 TRANSISTOR
 BATTERY

6.  Relay is an electromagnetic device which is used to isolate
two circuits electrically and connect them magnetically.
 They are very useful devices and allow one circuit to switch
another one while they are completely separate.
 They are often used to interface an electronic circuit
(working at a low voltage) to an electrical circuit which
works at very high voltage.
 For example, a relay can make a 5V DC battery circuit to
switch a 230V AC mains circuit. Thus a small sensor circuit
can drive, say, a fan or an
electric bulb.
 A relay switch can be divided into two parts: input and
output.

7. LIGHT DEPENDENT RESISTOR
 An LDR is an input transducer (sensor) which converts
brightness (light) to resistance.
 When the light level is low the resistance of the LDR is
high.
 Thus in this project, LDR plays an important role in
controlling the electrical appliances based on the
intensity of light i.e., if the intensity of light is more
(during daytime) the loads will be in off condition.

8. RESISTOR
 Resistor is a passive component used to control
current in a circuit.
 Its resistance is given by the ratio of voltage applied
across its terminals to the current passing through
it.
 Thus a particular value of resistor, for fixed voltage,
limits the current through it.
 Resistors can be either fixed or variable.

9. BC548 TRANSISTOR
 It is a general purpose silicon, NPN, bipolar junction
transistor. It is used for amplification & switching
purpose.
 Here, for switching purpose it is biased so that it
remains on if there is signal at its base , otherwise
it is completely off.

10. Advantages
 Highly sensitive
 Works according to the sun direction
 Fit and Forget system
 Night – Day mode sensing
 Low cost and reliable circuit
 Complete elimination of manpower