Automatic Street Light Control Using LDR SensorA PROJECT REPORT

Submitted in Partial Fulfilment for the degree of Bachelor of Technology in

ELECTRICAL ENGINEERING From

MAULANA ABUL KALAM AZAD UNIVERSITY OF TECHNOLOGY

Submitted byAmit Kumar

Ashish kumar SinghChandan KumarNeeraj kumar

Shubham Ghosh

Under the guidance ofMrs Tanushree Kumar

DEPARTMENT OF ELECTRICAL ENGINEERINGMCKV Institute of Engineering

243, G.T. Road (North), LILUAH, HOWRAHDEPARTMENT OF ELECTRICAL ENGINEERINMCKV

Institute of EngineeringAffiliated to

West Bengal University of Technology

NOVEMBER,2015

CERTIFICATE

This is to certify that the project report entitled “AUTOMATIC

STREETLIGHT CONTROL USING LDR SENSOR” submitted by “ AMIT

KUMAR , ASHISH KUMAR SINGH , CHANDAN KUMAR , NEERAJ

KUMAR , SHUBHAM GHOSH ” for 7th/8th semester examination have been

prepared following the guidelines of B.Tech degree in Electrical Engineering,

awarded by the Maulana Abul Kalam Azad University of Technology. They

have carried out the project work under my supervision.

Signature of the head of the department Signature of the supervisor

Prof. Chandrani Sadhukhan Mrs Tanushree Kumar HEAD OF THE DEPARTMENT SUPERVISOR

Assistant ProfessorElectrical Engineering Electrical Engineering

243 , G.T . Road(N) , Liluah 243 , G.T.Road (N) , LiluahHowrah-711204 Howrah-711204

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ACKNOWLEDGEMENT

We have taken efforts in this project. However, it would not have been possible

without the kind support and help of many individuals. I would like to extend

my sincere thanks to all of them.I am highly indebted to Mrs Tanushree Kumar,

Assistant prof. of the Department of Electrical Engineering, MCKV Institute of

Engineering for her guidance and constant supervision as well as for providing

necessary information regarding the project & also for their support in

implementing the project.My thanks and appreciations also go to my friends in

developing the project and people who have willingly helped me out with their

abilities.

-----------------------------------------------

Name and Signature of the candidate

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ABSTRACT

This project is all about to control the power consumptions and reducing the

manpower. This includes controlling with specific Sensors ( LDR) during day

and night.

Street Light Control System which operates automatically is not only easiest but

also the intelligent system. This system can be set to operate in automatic mode,

which regulates the streetlight according to brightness and dimness.

This design can save a great amount of electricity compared to streetlamps that

keep alight during nights.

The system can be widely applied in all places which need timely controlsuch

as streets, stations, mining, schools, and electricity sectors and so on.

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TABLE OF CONTENTS

CERTIFICATE 1ACKNOWLEDGEMENT 2ABSTRACT 3LIST OF FIGURES 5LIST OF TABLES 6CHAPTER-1 7.OBJECTIVE OF THE PROJECT 7CHAPTER-2 8INTRODUCTION 8CHAPTER-3 10LITERATURE REVIEW 10CHAPTER-4 12DESCRIPTON OF COMPONENT USED 124.1 DIODE 124.1.1 FORWARD BIASING CHARACTERISTIC OF DIODE 134.1.2 REVERSE BIASING CHARACTERISTIC OF DIODE 134.2 ZENER DIODE 144.2.1 ZENER DIODE CIRCUIT 154.2.2 CHARACTERISTICS OF A ZENER DIODE 164.2.3 APPLICATION OF ZENER DIODE 164.2.4 ZENER DIODE AS VOLTAGE REGULATOR 164.3 RESISTOR 174.4 CAPACITOR 184.4.1 TYPES OF CAPACITORS 18.4.5 TRANSISTOR 204.5.1 DEFINITION OF BJT 204.5.2 N-P-N BIPOLAR JUNCTION TRANSISTOR 214.5.3 P-N-P BIPOLAR JUNCTION TRANSISTOR 214.5.4 WORKING PRINCIPLE OF BJT 224.6 LIGHT DEPENDENT RESISTOR 22 4.6.1 WORKING PRINCIPLE OF LDR 23 4.6.2APPLICATIONS OF LDR 234.7 LED 244.7.1WORKING PRINCIPLE OF LED 244.8 POTENTIOMETER 254.9 DRY CELL 264.10 FUSE 27

5.1 CIRCUIT DIAGRAM 285.2 COMPONENT USED AND THEIR SPECIFICATION 295.3 WORKING OF THE CIRCUIT 30 CHAPTER- 6 37

SCOPE OF POWERING THE CUIRCUIT 37CHAPTER-7 38ADVANTAGES AND APPLICATION 38CHAPTER-8 39

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REFERENCE 39

LIST OF FIGURES

Page no. Fig.1 Symbol of diode 12Fig.2 Biasing of diode 13Fig.3 Forward biasing of diode 13Fig.4 Reverse biasing of diode 14Fig.5 Connection of diode as a zener diode 15Fig.6 Symbol of zener diode 15Fig.7 Characteristics of zener diode 15Fig.8Zener diode as voltage regulator 17Fig.9 Types of transistor 20Fig.10 n-p-n transistor 21Fig.11 p-n-p transistor 21Fig.12 Symbol of LDR 23

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Fig.13 Symbol of LED 24Fig.14 Symbol of Potentiometer 25Fig.15 Symbol of cell and battery 26Fig.16 A typical fuse used in the circuit 27Fig.17 Circuit diagram 28 Fig.18 Waveform across source 32Fig.19 Waveform after rectification 33 Fig.20 Waveform across zener diode 34Fig:-21Waveform across C2 35 Fig.22 Waveform across Emitter and Base 36

LIST OF TABLES Page no.

Table 1.Different components with their specifications 29

and price

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CHAPTER-1

OBJECTIVE OF THE PROJECT

Our objective is to reduce the power consumption and by employing this circuit

, energy consumption can be reduced considerably as the light switches ON or

OFF automatically in appropriate time.

Moreover , errors which occurs due to manual operation also can be eliminated

completely.

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The systemitself detects whether there is need for light or not. When darkness

rises to a certain value then automaticallystreetlight is switched ON and when

there is other source of light, the street light gets OFF.

The main advantages of this system consist in the reduction of the costs related

to energyconsumption.

CHAPTER-2

INTRODUCTIONBasically, street lighting is one of the important parts of a city’s infrastructure

where the main function is toilluminate the city’s streets during dark hours of

the day. Previously, the number of streets in the town and city is verysmall.

Therefore, the street lamps are relatively simple but with the development of

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urbanization, the number of streetsincreases rapidly with high traffic density.

There are several factors need to be considered in order to design a good

street lighting system such as night-time safety for community members and

road users, provide public lighting at costeffective, the reduction of crime and

minimizing it is effect on the environment. At the beginning, street lamps were

controlled by manual control where a control switch is set in each of the street

lamps. It is called first generation of theoriginal street light. After that, another

method that has been used was optical control method. Thismethod operates by

set up an optical control circuit, change the resistance byusing of light sensitive

device to controlstreet lamps light up automatically at dusk and turn off

automatically after dawn in the morning. Due to thetechnological development

nowadays, road lighting can be categorized according to the installation area,

performanceand their used, for an example, lighting for traffic routes, lighting

for subsidiary roads and lighting for urban center and public amenity areas.

Meanwhile, street lighting technology can be classified according to the type of

lamps used suchas incandescent light, mercury vapour light, metal halide light,

high pressure sodium light, low pressure sodium light,fluorescent light, compact

fluorescent light, induction light and LED light.Over the last few years, LED

street lamps have turned into real products that one can see on the road. They

makesense for many reasons, such as their compact size, high efficacy (lumens

per watt), longevity, and robustness. LEDsources also allow for interesting new

design forms, often with slimmer profiles than traditional metal halide arclamps.

LED is considered a promising solution to modern street lighting system due to

it is behaviour and advantagesas emphasized. Apart from that, the advantages of

LED are likely to replace the traditional street lamps such as theincandescent

lamp, fluorescent lamp and High Pressure Sodium Lamp in future but LED

technology is an extremelydifficult process that requires a combination of

advanced production lines, top quality materials and high-

precisionmanufacturing process. Therefore, this paper highlights the energy

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efficient of street lighting design using LEDlamps through intelligent sensor

interface for controlling and managing.The original contribution of this thesis is

to design of a streetlight node based on which the system can be set to

run in automatic mode, which control streetlight according to Sunrise and

Sunset Algorithm and light intensity. Thiscontrol can make a reasonable

adjustment according to the seasonal variation.

CHAPTER-3

LITERATURE REVIEW

Gustavo W. Denardin deals about a control network for a LED street lighting

system. The use of LEDs is being considered promising solution to modern

street lighting systems, dueto their longer lifetime, higher luminous efficiency

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and higherCRI.. In order to meet the system requirements, a wireless sensor

network based on IEEE 802.15.4TM standard is employed. Its network layer is

implemented using geographic routing strategy, which provides slow overhead

and high scalability features. However, due to well-known drawbacks of the

existing techniques, a novel routing algorithm is proposed. Simulations show

that this algorithm leads to a significant improvement of routing performance

when applied to sparse large scale scenarios, which is the case of street lighting

system. Field tests have been performed on IEEE 802.15.4-compliant wireless

control units. The obtained experimental results show that the proposed control

network is able to meet the requirements of a LED street lighting system. It

mainly deals about safer roadways with intelligent light system to reduce power

consumption. This system has automatic street light intensity control based on

the vehicular movement and switching ON and OFF of street lights depending

on the light ambiance.

A.C. deal about solar energy based street light with auto-tracking system for

maximizing power output from a solar system is desirable to increase the

efficiency. In order to maximize the power output from the solar panels, one

needs to keep panels aligned with the sun. As such a means of tracking the sun

is required. This is a far most cost effective solution than purchasing additional

solar panels. It has been estimated that the yield from solar panels can be

increased by 30 to 60 percent by utilizing a tracking system instead of a

stationary array. This paper describes an automatic tracking system which will

keep the solar panels aligned with the sun in order to maximize efficiency. The

sun tracking sensor is the sensing device, which sense the position of the sun at

the time to time continuously and it gives the sensing output to the amplifier

based on light density of the sun. Here the sun tracking sensor is LDR(light

dependent resistor). The amplifier unit is used to amplify the LDR signals,

which makes the low level signal into high level signals and this output is given

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to the comparator. The LM324 IC is used as an amplifier. Comparator compares

the signals and gives the command to the AT89C51 microcontroller. The

system presented in this paper will be an efficient method to use the solar

energy in remote areas. This system consumes very low power and high

efficient lightning. We employ the auto sun tracking system; this can improve

the energy stored in battery. This system does not affect the environment

because it is pollution free. Our system also consisting of automatic ON, OFF

control of the LED lamp, so there is no manual operation and it is not required

operators

S.H. Jeong describes about the Development of Zigbee based Street Light

Control System which control and monitor status of street lights installed

alongside load. Lights are switched to ON/OFF by this system’s control

command. Its local status information is also monitored by control system via

communication channel. Status information which is monitored are on/off status

information, energy saving mode status, control group status information and

safety related information, etc. To transfer control command and status

information between street light control system and remote street light control

terminals which installed at each light pole, various communication media and

communication protocols are using. As communication media, wireless or

power lines are used generally. Various frequency bands from tens of MHz to

Rebrands are used for wireless case. This Street light control system can save

maintenance time and costs and which can improve safety level.

CHAPTER-4

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DESCRIPTON OF COMPONENT USED

4.1 DIODEIn electronics, a diode is a two-terminal electronic component that conducts

primarily in one direction ; it has low (ideally zero) resistance to the flow

of current in one direction, and high (ideally infinite) resistance in the other.

The function of a diode is to allow an electric current to pass in one direction

(called the diode's forward direction), while blocking current in the opposite

direction (the reverse direction). Thus, the diode can be viewed as an electronic

version of a check valve. This unidirectionalbehaviour is called rectification,

and is used to convert alternating current to direct current.

A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals.

P-N junction is formed by bringing a P type material in contact with N type

material. When a P-type material is brought in contact with N- type material

electrons and holes start recombining near the junction. This result in lack of

charge carriers at the junction and thus the junction is called depletion region.

Symbol of P-N junction is given as:

Figure:-1. Symbol of diode

Biased i.e. when voltage is applied across the terminals of P-N junction, it is

called diode. Diode is unidirectional device that allows the flow of current in

one direction only depending on biasing.

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Figure:-2. Biasing of diode

4.1.1FORWARD BIASING CHARACTERISTIC OF DIODEWhen P terminal is more positive as compared to N terminal i.e. P- terminal

connected to positive terminal of battery and N-terminal connected to negative

terminal of battery , it is said to be forward biased.

Figure:-3. Forward biasing of diode

Positive terminal of thebattery repels majority carriers, holes, in P-region and

negative terminal repels electrons in the N-region and push them towards the

junction. This result in increase in concentration of charge carriers near

junction, recombination takes place and width of depletion region decreases. As

forward bias voltage is raised depletion region continues to reduce in width, and

more and more carriers recombine. This results in exponential rise of current.

4.1.2REVERSE BIASING CHARACTERISTIC OF DIODEIn reverse biasing P- terminal is connected to negative terminal of the battery

and N- terminal to positive terminal of battery . Thus applied voltage makes N-

side more positive than P-side.

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Figure:-4. Reverse biasing of diode

Negative terminal of thebattery attracts majority carriers, holes, in P-region and

positive terminal attracts electrons in the N-region and pull them away from the

junction. This result in decrease in concentration of charge carriers near junction

and width of depletion region increases. A small amount of current flow due to

minority carriers, called as reverse bias current or leakage current. As reverse

bias voltage is raised depletion region continues to increase in width and no

current flows. It can be concluded that diode acts only when forward biased.

4.2 ZENER DIODE

Zener diode it is nothing but a simple diode connecting in reverse bias. It is

mainly a special property of the diode rather than any special type of equipment.

Clearance Zener invented this property of the diode that’s why it is named after

him. The main principle of this special property is that there is a breakdown in

the circuit if the voltage applied across a reversely biased it does not allow the

current to flow across it. Now as the voltage across the diode is increased, the

temperature increases and the crystal ions vibrate with greater amplitude and all

these leads to the breakdown of the depletion layer(i.e, the layer at the junction

of p - type and n - type). And when the applied voltage exceeds anspecific

amount zener breakdown takes place.

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4.2.1 ZENER DIODE CIRCUITZener Diode is nothing but a single diode connected in a reverse bias, we have

already stated that. A diode connected in reverse bias positive in a circuit is

shown below,

Figure:-5 Connection of a diode as a Zener diode.

The circuit symbol of Zener diode is also shown below. For convenience and

understanding, it is used normally

Fig:-6. Symbol of Zener diode

Now, discussing about the diode circuits we should look through the graphical

representation of the operation of the zener diode. Normally it is called the V-I

characteristics of a general p - n junction diode.

Figure:-7. Characteristics of Zener Diode.

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4.2.2 CHARACTERISTICS OF A ZENER DIODE

The above diagram shows the V-I characteristics of the zener diode. When the

diode is connected in forward bias, this diode acts as a normal diode but when

the reverse bias voltage is greater than a predetermined voltage zener

breakdown voltage takes place. To make the breakdown voltage sharp and

distinct, the doping is controlled and the surface imperfections are avoided. In

the V-I characteristics above Vz is the zener voltage, we can say. It is also the

knee voltage because at this point the current is the current is very rapid.

4.2.3 APPLICATION OF ZENER DIODEOvervoltage protection is done by using Zener diodes because there is current

flowing through the diode after the reverse bias voltage exceeds a certain value.

This circuit provides safety for the equipment connected at the terminals.

Normally the current should not exceed normal valve but if due to any fault in

the circuit the current exceeds the maximum allowable limit, the equipment of

the system can be damaged permanently. A SCR is used, by it the output

voltage is quickly cut down and a fuse blows which disconnects the input

source power.

4.2.4 ZENER DIODE AS VOLTAGE REGULATORThe term regulator meanswhich regulates or controls. Zener diode can work as a

voltage regulator if it is introduced in a circuit. The output across the diode will

be constant. As we know if the voltage across the diode exceeds a certain value

it would draw excessive current from the supply. The basic diagram of zener

diode as voltage regulator is given below,

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Figure:- 8. Zener diode as voltage regulator

To limit the current through the Zener diode series resistance R is introduced whose value can be chosen from the following equation

Resistor value (ohms) = (V1 - V2) / (zener current + load current)

The above diagram is of a shunt regulators because the regulating element is parallel to the load. The Zener diode produce a stable reference voltage across the load which fulfils the criteria of regulator.

4.3 RESISTORA resistor offers resistance to the flow of current . The resistance is the measure

of opposition to the flow of current in a resistor. More resistance means more

opposition to current . The unit of resistance is ohm and it is represented as Ω.

When one volt potential difference is applied across a resistor and for that one

ampere of current flows through it, the resistance of the resistor is said to be one

Ω. Resistor is one of the most essential passive elements in electrical and

electronics engineering.

It is some time required to introduce electrical resistance in different circuit to

limit the current through it. Resistor is an element of circuit which does the

same. Such as series connected resistor limits the current flowing through the

light emitting diode (LED). In addition to that resistors serve many other

purposes in electrical and electronic applications.

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The most essential requirement of a resistor is that its value of electrical resistance should not vary with temperature for a wide range. That means resistance variation with temperature must be as minimal as possible for a wide range of temperature. In other word the temperature coefficient of resistance of must be minimum for the materials by which a resistor is made of.

4.4 CAPACITORCapacitor is a passive element that stores electric charge statistically and

temporarily as an static electric field. It is composed of two parallel conducting

plates separated by non-conducting region that is called dielectric, such as

vacuum, ceramic, air, aluminum, etc.

The capacitance formula of the capacitor is represented by,

C is the capacitance that is proportional to the area of the two conducting plates

(A) and proportional with the permittivity ε of the dielectric medium. The

capacitance decreases with the distance between plates (d). We get the greatest

capacitance with a large area of plates separated by a small distance and located

in a high permittivity material. The standard unit of capacitance is Farad, most

commonly it can be found in micro-farads, pico-farads and nano-farads.

4.4.1TYPES OF CAPACITORSThere are mainly two types of capacitor-

A) CERAMIC CAPACITORConstruction of ceramic capacitor is quite simple. Here, one thin ceramic disc is

placed between two metal discs and terminals are soldered to the metal discs.

Whole assembly is coated with insulated protection coating.

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B) ELECTROLYTE CAPACITOR

Very large value of capacitance can be achieved by this type of capacitor. But

working voltage level of this electrolyte capacitor is low and it also suffers from

high leakage current. The main disadvantage of this capacitor is that, due to the

use of electrolyte, the capacitor is polarized. The polarities are marked against

the terminals with + and – sign and the capacitor must be connected to the

circuit in proper polarity.

A few micro meter thick aluminium oxide or tantalum oxide film is used as

dielectric of electrolyte capacitor. As this dielectric is so thin, the capacitance of

this type of capacitor is very high. This is because; the capacitance is inversely

proportional to thickness of the dielectric. Thin dielectric obviously increases

the capacitance value but at the same time, it reduces working voltage of the

device. Tantalum type capacitors are usually much smaller in size than the

aluminium type capacitors of same capacitance value. That is why, for very

high value of capacitance, aluminium type electrolyte capacitors do not get used

generally. In that case, tantalum type electrolyte capacitors get used.

Aluminium electrolyte capacitor is formed by a paper impregnated with an

electrolyte and two sheets of aluminium. These two sheets of aluminium are

separated by the paper impregnated with electrolyte. The whole assembly is

then rolled up in a cylindrical form, just like a simple paper capacitor. This roll

is then placed inside a hermetically sealed aluminium canister. The oxide layer

is formed by passing a charging current through the device, and it is the polarity

of this charging process that determines the resulting terminal polarity that must

be subsequently observed. If the opposite polarity is applied to the capacitor, the

oxide layer is destroyed.

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4.5 TRANSISTOR

4.5.1 DEFINITION OF BJTA bipolar junction transistor is a three terminal semiconductor device consisting

of two p-n junctions which is able to amplify or “magnify” a signal. It is a

current controlled device. The three terminals of the BJT are the base, the

collector and the emitter. A signal of small amplitude if applied to the base is

available in the amplified form at the collector of the transistor. This is the

amplification provided by the BJT. Note that it does require an external source

of DC power supply to carry out the amplification process.

The basic diagrams of the two types of bipolar junction transistors mentioned

above are given below.

Figure:-9. Types of transistor

From the above figure, we can see that every BJT has three parts named emitter,

base and collector. JE and JC represent junction of emitter and junction of

collector respectively. Now initially it is sufficient for us to know that emitter

based junction is forward biased and collector base junctions is reverse biased.

The next topic will describe the two types of this transistor.

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4.5.2N-P-N BIPOLAR JUNCTION TRANSISTORAs started before in n - p - n bipolar transistor one p - type semiconductor

resides between two n - type semiconductors the diagram below a n - p - n

transistor is shown

Figure:-10. n-p-n transistor

Now IE, IC is emitter current and collect current respectively and VEB and VCB

are emitter base voltage and collector base voltage respectively. According to

convention if for the emitter, base and collector current IE, IB and ICcurrent goes

into the transistor the sign of the current is taken as positive and if current goes

out from the transistor then the sign is taken as negative.

4.5.3P-N-P BIPOLAR JUNCTION TRANSISTORSimilarly for p - n - p bipolar junction transistor a n-type semiconductors is

sandwiched between two p-type semiconductors. The diagram of a p - n - p

transistor is shown below

Figure:-11. p-n-p transistor

For p - n - p transistors, current enters into the transistor through the emitter

terminal. Like any bipolar junction transistor, the emitter – base junction is

forward biased and the collector – base junction is reverse biased.

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4.5.4 WORKING PRINCIPLE OF BJTFigure shows an n-p-n transistor biased in the active region (See transistor

biasing), the BE junction is forward biased whereas the CB junction is reversed

biased. The width of the depletion region of the BE junction is small as

compared to that of the CB junction. The forward bias at the BE junction

reduces the barrier potential and causes the electrons to flow from the emitter to

base. As the base is thin and lightly doped it consists of very few holes so

someof the electrons from the emitter (about 2%) recombine with the holes

present in the base region and flow out of the base terminal. This constitutes the

base current, it flows due to recombination of electrons and holes (Note that the

direction of conventional current flow is opposite to that of flow of electrons).

The remaining large number of electrons will cross the reverse biased collector

junction to constitute the collector current. Thus by KCL,

The base current is very small as compared to emitter and collector current.

Here, the majority charge carriers are electrons. The operation of a p-n-p

transistor is same as of the n-p-n, the only difference is that the majority charge

carriers are holes instead of electrons. Only a small part current flows due to

majority carriers and most of the current flows due to minority charge carriers

in a BJT. Hence, they are called as minority carrier devices.

4.6 LIGHT DEPENDENT RESISTORA Light Dependent Resistor (LDR) or a photo resistor is a device whose

resistivity is a function of the incident electromagnetic radiation. Hence, they

are light sensitive devices. They are also called as photo conductors, photo

conductive cells or simply photocells. They are made up of semiconductor

materials having high resistance. There are many different symbols used to

indicate a LDR, one of the most commonly used symbol is shown in the figure

below. The arrow indicates light falling on it.

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Figure:-12. Symbol of LDR

4.6.1WORKING PRINCIPLE OF LDRA light dependent resistor works on the principle of photo conductivity. Photo

conductivity is an optical phenomenon in which the materials conductivity

(Hence resistivity) reduces when light is absorbed by the material.

When light falls i.e. when the photons fall on the device, the electrons in the

valence band of the semiconductor material are excited to the conduction band.

These photons in the incident light should have energy greater than the band

gap of the semiconductor material to make the electrons jump from the valence

band to the conduction band. Hence when light having enough energy is

incident on the device more & more electrons are excited to the conduction

band which results in large number of charge carriers. The result of this process

is more and more current starts flowing and hence it is said that the resistance of

the device has decreased.This is the most common working principle of LDR

4.6.2Applications of LDRLDR’s have low cost and simple structure. They are often used as light sensors.

They are used when there is a need to detect absences or presences of light like

in a camera light meter. Used in street lamps, alarm clock, burglar alarm

circuits, light intensity meters, for counting the packages moving on a conveyor

belt, etc.

4.7 LED

A light-emitting diode (LED) is a two-lead semiconductor light source. It is a

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 p–n junction diode, which emits light when activated.When a suitable voltage

 is applied to the leads, electrons are able to recombine with electron holes

 within the device, releasing energy in the form of photons. This effect is

called electroluminescence, and the color of the light (corresponding to the

energy of the photon) is determined by the energy band gap of the

semiconductor.

An LED is often small in area (less than 1 mm2) .

Fig:-13.Symbol of LED

4.7.1 WORKING PRINCIPLE OF LED

A P-N junction can convert absorbed light energy into a proportional electric

current. The same process is reversed here (i.e. the P-N junction emits light

when electrical energy is applied to it). This phenomenon is generally

called electro luminescence, which can be defined as the emission of light from

a semi-conductor under the influence of anelectric field. The charge carriers

recombine in a forward-biased P-N junction as the electrons cross from the N-

region and recombine with the holes existing in the P-region. Free electrons are

in the conduction band of energy levels, while holes are in the valence energy band.

Thus the energy level of the holes will be lesser than the energy levels of the

electrons. Some portion of the energy must be dissipated in order to recombine

the electrons and the holes. This energy is emitted in the form of heat and light.

The electrons dissipate energy in the form of heat for silicon and germanium

diodes but in gallium arsenide phosphide (GaAsP) and gallium phosphide (GaP)

semiconductors, the electrons dissipate energy by emitting photons. If the

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semiconductor is translucent, the junction becomes the source of light as it is

emitted, thus becoming a light-emitting diode, but when the junction is reverse

biased no light will be produced by the LED and, on the contrary, the device

may also be damaged.

4.8POTENTIOMETERA potentiometer, informally a pot, is a three-terminal resistor with a sliding or

rotating contact that forms an adjustable voltage divider. If only two terminals

are used, one end and the wiper, it acts as a variable resistor or rheostat.

The measuring instrument called a potentiometer is essentially a voltage divider

used for measuring electric potential (voltage); the component is an

implementation of the same principle, hence its name.

Potentiometers are commonly used to control electrical devices such as volume

controls on audio equipment. Potentiometers operated by a mechanism can be

used as position transducers, for example, in a joystick. Potentiometers are

rarely used to directly control significant power (more than a watt), since the

power dissipated in the potentiometer would be comparable to the power in the

controlled load.

Fig:-14. Symbol of potentiometer

4.9 DRY CELL

A Dry cell is a type of electricity-producing chemical cell, commonly used

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today for many home and portable devices, often in the form of

batteries.

A dry cell uses a paste electrolyte, with only enough moisture to allow current

to flow. Unlike a wet cell, a dry cell can operate in any orientation without

spilling, as it contains no free liquid, making it suitable for portable equipment.

A standard dry cell comprises a zinc anode, usually in the form of a cylindrical

pot, with a carbon cathode in the form of a central rod.

Theelectrolyte is ammonium chloride in the form of a paste next to the zinc

anode. The remaining space between the electrolyte and carbon cathode is taken

up by a second paste consisting of ammonium chloride and manganese dioxide,

the latter acting as a depolariser. In some designs, the ammonium chloride is

replaced by zinc chloride.

Fig:-15.Symbol of cell and battery

4.10 FUSE

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In normal working condition of electrical network, the current flows through the

network is within the rated limit. If fault occurs in the network mainly phase to

phase short circuit fault or phase to ground fault, the network current crosses the

rated limits. This high current may have very high thermal effect which will

cause a permanent damage to the valuable equipments connected in the

electrical network. So this high fault current should be interrupted as fast as

possible. This is what an electrical fuse does. A fuse is a part of the circuit

which consists of conductor which melts easily and breaks the connection when

current exceeds the predetermined value. An electrical fuse is a weakest part of

an electrical circuit which breaks when more than predetermined current flows

through it.

Fig:-16 A typical fuse used in the circuit

CHAPTER-5

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5.1 CIRCUIT DIAGRAM

Figure:-17. Circuit diagram

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5.2COMPONENT USED AND THEIR SPECIFICATION

Serial No. Components Specifications Price (Rs)

1. A Capacitor 2.2uF,250v,Non electrolytic

7

B 47uF,25vElectrolytic

1

C 22uF,25vElectrolytic

1

2.A Resistor 330k ohm 0.20 B 10 ohm 0.20 C 47k ohm 0.20 D 10k ohm 0.20 E 2.2k ohm 0.20

F 390 ohm 0.20 G 100 ohm 0.203 Variable Resistor 20k ohm 24 Diode(4 pcs.) In4007 0.50*4= 25 Zener Diode A010 0.506 LDR Roboindia 37 White LED 58 Transistor Bt3904 39 Breadboard 8010 Wires 1011 Plug 10

Table:-1 Different components and their specification and price

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5.3 WORKING OF THE CIRCUITThis circuits operates with voltage from120 -220 volts .Therefore the

capacitor(C1) of the current input (225) is at least 250 volts and the

rectification condenser (C2) (22 uF) is 350 volt, because if this circuit fed with

220v AC , when to be ground becomes approximately 330v DC .

The bulb can be up to 100 watt. We can use one for more power as long as

change the triac BT136 for one that supports more amps as BTA08600 ,

supporting up to 8 amps .

One of the great virtue of this circuit is that no need of transformer .in this case

we use a very simple circuit low voltage and rectifies , saving money and space.

The capacitor (C1) 2.2 uF polyster in series with the input voltage public

network, restricting the flow of current. The capacitor allows the passage of

only approximately 16mA providing voltage reduction will be done later. 330 k

resistor (R1) which is parallel with capacitor (C1) , is responsible for

discharging the capacitor when the circuit off , preventing the condenser is

charged and can send an electric shock , when handling the circuit .

At the other input cable is a public network 10 ohm resistor (R2) functioning as

fuse and helps to limit the current.

After the current passes through the capacitor and resistor, reaches a diode

bridge formed by four rectifying diodes, which are responsible for separating

the positive half cycle of negative, delivering separately and then be rectified by

a capacitor (C2) converting alternating current (AC) into direct current (DC)

recall that to rectify a current the voltage rises , multiplying by root of 2 is 1.414

. And for a 230 AC power, we will have an output voltage of about 325 volts

DC approx. For this reason the rectifier capacitor source must be 350 volts,

otherwise it will explore when connecting the circuit.

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Now that the rectifier and a small current voltage, we must lower the voltage to

10 volts DC. For this we use a Zenor Diode. It is important to note that a Zener

Diode do not connect without there respective wire resistor that limits the

current that feeds the Zener , otherwise the Zener will burn.

39k 5w resistor (R3) is the polarization resistance of the Zener. It needs to be a

5w, as the effort we have to do lower the current generates a relatively high

heat. The formula for calculating the resistance is:

Rz = (Vt-Vz)/Iz.

= total polarization resistance voltage minus the zener voltage divided by the

Zener Amps.

We must:

(305Vdc – 10Vdc)/0.02 Amps = 14750 ohms.

It could be a 50k resistor, but when testing is too hot, so we wanted to find the

highest resistance before the voltage drops power failure. The maximum

resistance is 47k and the minimum without excess heat is 33k.

The 10 k resistor (R4) it helps the zener to handle the load, it runs parallel to

earth with the zener diode.

The 47 uF capacitor (C3) and . 1 uF ceramic capacitor (C4) again rectified

current removing possible curls.

Now coming to the automation part,

When it’s light, the photo resist is receiving light, the LDR has low impedance

(0 ohm), negatively biasing the base of the transistor. Therefore transistor

remains turned off as it is npn transistor. when the environment is dark, the

photo resist impedance rises to over 100 k , restricting the flow of current. This

makes the voltage at the base of the transistor higher. High enough to turn the

transistor ON. Because the transistor is turned on, current flows through the

transistor. It flows from the positive battery terminal, through R5, the LED, and

the transistor down to the negative battery terminal. This makes the LED light

up.

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Fig:-18.Waveform across source

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Fig:-19.Waveform after rectification

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Fig:-20.Waveform across zener diode

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Fig:-21.Waveform across c2

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Fig:-22.Waveform across Emitter and Base

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CHAPTER- 6

SCOPE OF POWERING THE CUIRCUIT1.The above circuit can be powered from a battery, which can be charged

during day time by harvesting the solar energy through a solar cell.

2.The AC voltage from electric grid can be stepped down, rectified and used for

powering the circuit.

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CHAPTER-7

ADVANTAGES AND APPLICATION

By employing this circuit, energy consumption can be reduced considerably as

the light switches ON or OFF automatically in appropriate time.Moreover,

errors which occur due to manual operation can be eliminated completely.The

automatic street light controller unit fabrication is cost effective with good

sensitivity .Also the construction of the circuit is simple that it can be done

easily as it involves locally available components. The circuit is designed in

such a way that the extent of darkness which the light has to switch ON or OFF

also can be tailored whenever it is needed. It can be used for other purposes like

garden lighting, balcony lighting etc.

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CHAPTER-8

REFERENCE

1. International Journal of Innovative Research in Science, Engineering and

Technology (AN ISO 3297: 2007 Certified Organization) Vol. 3, Issue 2,

February 2014 (ISSN: 2319-8753)

www.ijirset.com

2. “A New Streetlight Monitoring System Based On Wireless Sensor Networks”

IEEE 2010

3. “Automatic Street Light Intensity Control and Road Safety Module Using

Embedded System” International Conference on Computing and Control

Engineering (ICCCE 2012), 12 & 13 April, 2012.

4. www.electrical4u.com

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