Light is a form of energy which stimulates the sense of vision. There are two types of light
which are natural light and artificial light. Example of natural light is sun and example of
artificial light is manmade efflorescent lamps which need power to give off light. Due to
demand of power these lamps needs high power, but when people fail to control those
lamps it tends to waste a lot of energy especially during the day where the use of artificial
power is not necessary to be used.
The problem of power consumption in our country have become a great problem, this is
due to the use of conversional switches that needs people to switch ON or OFF at required
time. This situation results the persistence lighting of the lamps as the result more energy
are consumed.
Problem statement

More energy is consumed during the day for nothing due to use of conversional
switches this is when a person forgets to switch OFF.

The objectives of the project are divided into main objective and specific objectives.
Main Objective
The main objective of this project is to reduce the problem of high power consumption
which increase the running cost to the people or user.
Specific Objectives
• To design and implement light/dark sensing circuit.
• To design and implement an automatic switching ON/OFF street light circuit.
Significances of the project
• .To minimize the cost.
• To ensure the safety of the community or user.
• To lower the energy consumption.
Existing System
Up to this time the existing system uses conversional switches which need a person to
switch it OFF or ON. This system is not better for energy conservation because when a
person forgets to switch it OFF during the day the lamps will be lighting hence consume
more energy.
Drawback of Existing System
The existing system has a disadvantage that it has a time delay of switching ON and OFF
due to human error.

Proposed System
The proposed system will use sensor to control the lighting of the lamp that is at the
presence of light and the absence of light.

Advantages of Proposed System
• Energy consumption is reduced.
• It is not costly.
• To avoid the common problem like overload, relay chattering and inductive
kickback on the relay.
• No wasting of time.
• Light switches ON/OFF in appropriate or at required time

Circuit Operation
The alternating current voltage (230 V) is stepped down to (12 V) using a suitable step
down transformer. The stepped down AC voltage is rectified to direct current Voltage
using a full wave bridge rectifier. To obtain a constant ripple-free DC voltage, a capacitor
filter is used across the circuit.
LDR offers Very high Resistance in darkness. In this case the voltage drop across the LDR
is more than 0.7V. This voltage is more sufficient to drive the transistor into saturation
region. In saturation region, IC (Collector current) is very high. Because of this IC, The
relay gets energized, and switches on the lamp. LDR offers Very low Resistance in
brightness. In this case the voltage drop across the LDR is less than 0.7V. This voltage is
not sufficient to drive the transistor into saturation region. Hence, the transistor will be in
cut-off region. In cut-off region, IC (Collector current) is zero. Because of this IC, The
relay will not be energized, and the lamp will be in ON state only [4]. Diode is connected
across the relay to neutralize the reverse EMF generated.

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