8/9/2019 P-1644--Automatic Street Light Controller 3

1/15

1. Introduction

Automatic Street Light Control System is a

simple and powerful concept, which uses transistor as a

switch to switch ON and OFF the street light

automatically. By using this system manual works are

remoed. !t automatically switches ON lights when the

sunlight goes "elow the isi"le region of our eyes. !t

automatically switches OFF lights under illumination "y

sunlight. #his is done "y a sensor called Light

$ependant %esistor &L$%' which senses the light

actually like our eyes.

By using this system energy consumption

is also reduced "ecause now(a(days the manually

operated street lights are not switched o) properly

een the sunlight comes and also not switched on

earlier "efore sunset. !n sunny and rainy days, ON time

and OFF time di)er signi*cantly which is one of thema+or disadantage of using timer circuits or manual

operation.

#his pro+ect eploits the working of a

transistor in saturation region and cut(o) region to

switch ON and switch OFF the lights at appropriate time

-

8/9/2019 P-1644--Automatic Street Light Controller 3

2/15

with the help of an electromagnetically operated

switch.

Automatic Streetlight needs no manual

operation of switching ON and OFF. #he system itself

detects whether there is need for light or not. hen

darkness rises to a certain alue then automatically

streetlight is switched ON and when there is other

source of light, the street light gets OFF. #he etent of

darkness at which the street light to "e switched on can

also "e tailored using the potentiometer proided in the

circuit.

2. Principle

#he automatic streetlight control system operates on

-/ 0 $C supply. #he automatic streetlight controller has

a photoconductie deice whose resistance changes

proportional to the etent of illumination, which

switches ON or OFF the L1$ with the use of transistor

as a switch

.

Light dependent resistor, a

photoconductie deice has "een used as the

/

8/9/2019 P-1644--Automatic Street Light Controller 3

3/15

transducer to conert light energy into electrical

energy. #he central dogma of the circuit is that the

change in oltage drop across the light dependent

resistor on illumination or darkness switches the

transistor "etween cut(o) region or saturation region

and switches OFF or ON the L1$.

3. Block Diagram Circuit Diagram

3.1 Block Diagram

3.1.1 Individual Block Explanation

Power supply AC power supply is stepped down,recti*ed and *ltered to get almost ripple(free $C outputfor the operation of the circuit.

2

8/9/2019 P-1644--Automatic Street Light Controller 3

4/15

!ig"t dependent resistor L$% senses theillumination leel and gies the input signal as oltagedrop.

#mpli$er$arlington circuit ampli*es the input currentto get maimum current gain.

%witc" %elayswitch closes or opens electrically andautomatically, which is energi3ed or de energi3ed "ythe $arlington pair.

%treet lig"t Street light is the output of the circuit. !nthis circuit, it has "een replaced "y L1$

3.1.3 &' &(( control

#he circuit is switched ON or OFF "y the transistor in

saturation region or cut o) region respectiely, which is

controlled "y the signal from L$%. #he collector current

from the transistor toggle "etween ON or OFF modes.

3.2 Circuit Diagram

4

8/9/2019 P-1644--Automatic Street Light Controller 3

5/15

-(!dentify all of the parts re5uired for all three circuits"ellow in the parts list6

/(Before starting ensure power supply is not connected

2(7se the Frit3ing Bread"oard Layout and Schematic$iagram images to connect the components with

prototyping wires to complete 8Circuit - 9 -:;%esistorotentiometer