Automatic Street Light control

using LDR

SABIR ALI MOLLAH

NAME-SABIR ALI MOLLAH

ALIAH UNIVERSITY

KOLKATA

Contents

Introduction

Circuit Diagram

Hardware Requirement

Description of Hardware

Working

Bread-board Mounting

PCB Mounting

Conclusion

SABIR ALI MOLLAH

Introduction

Many of the people have a phobia of darkness, soto assist them in such situation, we have explaineda simple circuit. It will automatically turn on streetlight in the way of LEDs or bulb coupled with relay.Working this circuit is very much easy and also thepower consumed by the circuit is very low becauseof the very few components used in the circuit.

SABIR ALI MOLLAH

Circuit diagram

SABIR ALI MOLLAH

Components:

Diodes - 4

Resistor R1 (10 K) – 1

Resistor R2 (3300 E) – 1

Resistor R3 (1 K) – 1

Variable Resistor VR1 (10 K) – 1

Capacitor C1 (470uF) – 1

Capacitor C2 (200uF) - 1

LDR – 1

Transistor T1 (BC548) – 1

Relay-1

LED-5SABIR ALI MOLLAH

Description of Hardware :

(1) LDR:

Sensitivity depends on intensity of

light.

Resistance of LDR decrease with

increase in intensity of light and

vice-versa.

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(2) 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

SABIR ALI MOLLAH

(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.SABIR ALI MOLLAH

Bridge rectifier

A diode bridge is an arrangement of four (or more) diodes in a bridge circuit configuration that provides the same polarity of output for either polarity of input.

When used in its most common application, for conversion of an alternating current (AC) input into a direct current (DC) output, it is known as a bridge rectifier. A bridge rectifier provides full wave rectification from a two-wire AC input, resulting in lower cost and weight as compared to a rectifier with a 3-wire input from a transformer with a center tapped secondary winding.

The essential feature of a diode bridge is that the polarity of the output is the same regardless of the polarity at the input.

SABIR ALI MOLLAH

Capacitors

A capacitor is a passive two terminal electrical

component that stores electrical energy in an electric

field. The effect of a capacitor is known as capacitance.

While capacitance exists between any two electrical

conductors of a circuit in sufficiently close proximity, a

capacitor is specifically designed to provide and enhance

this effect for a variety of practical applications by

consideration of size, shape, and positioning of closely

spaced conductors, and the intervening dielectric material.

SABIR ALI MOLLAH

Working of Automatic Street Light Controller

Switch Circuit:

The working of circuit is very much easy to

understand. In this circuit, we used transformer

which will basically convert the high voltage at

input into small voltage. After it we put bridge

rectifier which will convert ac into dc current and

provide pure dc current.

In this LDR and VR1 form one potential divider .

Here transistor is also placed which will basically

act as switch. Transistor will be operating in

cutoff and saturation mode to act as switch.SABIR ALI MOLLAH

SABIR ALI MOLLAH

SABIR ALI MOLLAH

Advantages:

No man power required.

Simple Construction.

Efficient method.

Less Consumption of electrical energy.

Less maintenance.

Cheap and economical.

SABIR ALI MOLLAH

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.

SABIR ALI MOLLAH

SABIR ALI MOLLAH