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1. Automatic Street Light control
using LDR
Compiled by
S.Sushmitha 13UG1A0448
S.Navaneetha 13UG1A0447
S.Mallikarjun 13UG1A0449
B.Shashirekha 13UG1A0405

2. Contents
Introduction
Existing Method
Proposal Method
Block diagram
Hardware Requirement
Description of Hardware
Working
Result
Conclusion

3. Introduction:
• Automatic Street Light Control System Is A Simple
Yet Powerful Concept, Which Uses Transistor As A Switch.
By Using This System Manual Works Are 100% Removed. It
Automatically Switches ON Lights When The Sunlight
Goes Below The Visible Region Of Our Eyes.
• This Is Done By A Sensor Called Light Dependant
Resistor (LDR) Which Senses The Light Actually Like Our
Eyes. It Automatically Switches OFF Lights Whenever The
Sunlight Comes, Visible To Our Eyes.

4. Existing Methods:
 It became essential for people work during nights and
returning back to homes late nights; also increasing
crime rate during night times.
 This can be best achieved by implementing proper
LDR based lighting system on Streets.

5. Proposal Method:
 Street light controllers are smarter versions of the
mechanical or electronic timers previously used for
street light ON-OFF operation.
 They come with energy conservation options like
twilight saving, staggering or dimming. Also many
street light controllers come with an astronomical
clock for a particular location or a Global Positioning
System (GPS) connection to give the best ON-OFF
time and energy saving

6. Block Diagram:
Micro
controller
AT89S52
POWER
SUPPLY
STREET
LIGHTS
LCD
16X2 LINES
LDR

7. Description of Hardware :
LDR:
 Sensitivity depends on
intensity of light.
 Resistance of LDR decrease
with increase in intensity of
light and vice-versa.

8. Resistor:
 It is a passive component having two terminals that are
used to manage the current flow in the circuit.
 A current that flows via a resistor is directly
proportional to the voltage that appeared into resistor.
 Two types:
(1) Fixed value resistor
(2) Variable resistor

9. (3)IC AT89S52:

10. IC
 The CA 3140 is an operational amplifier can
works on supply voltage 4V to 36V & very
low input current from 10pA to 1mA.
 Here, The CA3140 works as a comparator
and gives fast response &high speed.

11. (4) Relays
Relays is an electrically operated switch.
Current flowing through the coil of the relay creates a
magnetic field which attracts a lever & changes the
switch contacts.
It has 3-pin,4-pin,5-pin etc…but we have used 5-pin in
our circuit diagram.

12. Relay offers easy way for LED to indicate a voltage
is present at Relay coil.
As no input state,
the COM is connected
To NC & when operating
V is applied to relay coil
Gets energized &COM
Is now with NO.

13. (5) 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 , other-
wise it is completely off.

14. Working of Automatic Street Light Controller Switch
Circuit:
The working of circuit is very much easy to
understand. In this circuit, we used IC CA3140
which is basically an operational amplifier. Pins 2
and 3 of these IC are used to compare the voltage
and give us the output in return i.e. it works as a
potential divider in its inverting and non-inverting
inputs (pins 2 and 3).

15. Cont.
In this LDR and VR1 form one potential divider which
is used to provide a variable voltage at the inverting
input (that is 2) and the second potential divider is
built around non-inverting input (pin 3) with the help
of R1 and R2 which will grant half of the supply voltage
to non inverting pin.

16. Cont.
As we know property of LDR that during the time of
day resistance is low therefore voltage at the inverting
input ( IE pin 2) is higher than the voltage at the non-
inverting input (pin3) hence the output at the pin6 is
low so the transistor goes into the cutoff state which
means LED or bulb will not glow.

17. Cont.
But in dimness or in night we know that resistance of
LDR is high hence voltage at inverting input pin 2 of
the IC CA3140 decreases than the non inverting input
pin 3 as a result output pin 6 moves to high state
which make transistor to conduct and the LED or bulb
associated to it start simmering.

18. LCD:
LEDs are semiconductor diodes, electronic devices
that permit current to flow in only one direction. The
diode is formed by bringing two slightly different
materials together to form a PN junction

19. Result:
The sunlight is
off the night
mode to
activated the
LDR and street
lights will on

20. The sunlight is
on the day mode
to activated the
LDR and street
lights will off

21. Advantages:
No man power required.
Simple Construction.
Efficient method.
 Less Consumption of electrical energy.
Less maintenance.
Cheap and economical.

22. APPLICATIONS:
 Used in street light applications.
 Garden lights
 Balcony/Stair case/Parking lightings

23. Future scope:
 Wireless is the buzz of communication industry today.
The field of wireless communication is growing leaps
and bounds day by day.
 The main aim of the project is to save the power, by
using effectively we can save more power, as we know
that there is shortage of power nowadays in
everywhere mostly in villages etc.
 So to overcome that we can provide street lights
automatically with the centralized intelligent systems.
So in future we can design many more advanced
technologies to save power.

24. Softwares:
Soft wares used are:
 Keil software
 Express PCB for lay out design

25. Conclusion:
In coming days, this will prove a great boon to the
world, since it will save a lot of electricity of power
plants that gets wasted in illuminating the street
lights. As the conventional sources are depleting very
fast, then it`s time to think of alternatives.