This document presents a project on an automatic light control circuit that can switch lights on and off without manual operation based on ambient light levels. The circuit uses an LDR sensor to detect light intensity and control a relay driver IC and relay to power the lights. It includes sections describing the hardware requirements, circuit diagram, components, simulation, PCB layout, advantages, and conclusions. The system is intended to automatically control lights to save electricity while requiring minimal maintenance.

1. Presentation on
Automatic Light
control at Night
College of Engineering Science
& Technology, Lucknow
Submitted To:-
Electrical & Electronics
Department
Submitted By:-
Shubhan Raj
Karan Pratap Singh
Deepshikha Tiwari
Shikha Sharma

2. Abstract:-
 Automatic light needs no manual operation for
switching ON and OFF when there is need of light.
 In fact we can use this circuit to implement any type
of automatic night light.

3. Contents
 Introduction
 Hardware Requirement
 Block Diagram
 Circuit Diagram
 Hardware Discription
 Simulation
 PCB Layout
 Advantage
 Conclusion

4. Introduction
 Automatic light needs no manual operation for switching
ON and OFF when there is need of light.
 It detects itself whether there is need for light or not. When
darkness rises to a certain value then automatically light is
switched ON and when there is other source of light i.e.
day time, the light gets OFF.
 The sensitive of the light can be adjusted. The circuit thus
saves the electrical power as well as man power.
 The principle involves the detection of the intensity of light
with help of LDR which changes the value of resistance
across it on the basis of light.

5. Block diagram:

6. Circuit Diagram:

7. Components:
 LDR
 IC ULN2803 (Relay Driver)
 IC LM 324
 LM7805 (Voltage Regulator)
 Resistor
 Variable Resistor
 Capacitor
 Relay
 LED
 Bulb
 Connection wire
 Soldering Tools

8. LDR
 The light dependant resistor is an electronic component
whose resistance decreases with increasing light
intensity. It is also called as “Photo Resistor” or “Photo
conductor”
 The light dependant resistor uses high resistance
semiconductor material. (Cadmium Sulphide).When light
falls on such a semiconductor the bound electrons [i.e.
Valence electrons] get the light energy from the incident
photos
Description of Hardware :

9. LED
 A light-emitting diode (LED) is a semiconductor light
source. LEDs are used as indicator lamps in many
devices and are increasingly used for other lighting
 Appearing as practical electronic components early
LEDs emitted low-intensity red light, but modern
versions are available across the visible, ultraviolet,
and infrared wavelengths, with very high brightness.

10.  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
Resistor:

11. Relay Driver
 The eight NPN Darlington connected transistors in this family of
arrays are ideally suited for interfacing between low logic level
digital circuitry (such as TTL, CMOS or PMOS/NMOS) and the
higher current/voltage requirements of lamps, relays, printer
hammers or other similar loads.
 The major advantage of using this IC is that it can fulfill the
need for high voltage and high current also. This is enabled
through a low voltage and low current source to give high
voltage and high current output.

12. LM324
 LM324 is a 14pin IC consisting of four independent
operational amplifiers compensated in a single
package.
 Op-amps are high gain electronic voltage amplifier
with differential input and, usually, a single-ended
output. The output voltage is many times higher than
the voltage difference between input terminals of an
op-amp.

13. Voltage Regulator
 A voltage regulator is designed to automatically
maintain a constant voltage level
 Voltage regulator ICs are available with fixed voltage
(typically 5, 12 and 15V) or variable output voltages
 For ICs within the 78xx family, the xx is replaced with
two digits, indicating the output voltage (for example,
the 7805 has a 5 volt output, while the 7812
produces 12 volts)

14. Relay
 Relays are electromechanical switches.
 Relays have two circuits: A control circuit (shown in
GREEN) and a load circuit (shown in RED).
 The control circuit has small control coil while the
load circuit has a switch. The coil controls the
operation of the switch.

15. Capacitor
 To store electricity, or electrical energy.
 Also functions as filter, passing AC, and blocking
DC.
 Apply DC voltage- electric charge is stored on each
electrode.
 Three types of capacitor i.e. ceramic capacitor &
electrolytic capacitor and variable.
 Variable capacitors.

16. Simulation (using Proteus):

17. PCB Layout

18. Advantages:
 No man power required.
 Less Consumption of electrical energy.
 Less maintenance.
 Cheap and economical.
Disadvantage:-
In Sunny and rainy days, on and off time differ
notice.

19. 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.

20. Future Scope:-
 We can implement this project for street
lamp and also for night lamp of the room.