1

CHAPTER- 1I N T R O D U C T I O N

1.1 GENERAL DISCUSSIONThe project’s aim is to focus on how to make our livelihood more eco-friendly by utilizing

natural energy and simultaneously trying to incorporate it with our daily needs. It is to

enlighten the common folk how solar energy can be used in our daily life and how it is a

brilliant alternative to other natural sources like fossil fuels which causes pollution in nature

and which isn’t non-renewable. Solar energy is being converted to electrical energy and then

that energy is utilized for SMART street lighting where the intensity and timing of them are

controlled according to the sunlight varying throughout the day. The basic principle is the

dimming of the lights and decrement of intensity at dawn ultimately switching off and vice

versa as night approaches. Power consumption is also kept in focus and, undoubtedly it is low

as the base of the project happens to be on a renewable energy source. The proposed project

was entirely completed and is highly successful.

1.2 MOTIVATION BEHIND THIS WORKMotivation behind work is an important factor in any kind of project as it is the twitch of light

which causes us to move forward through any trial and complete the work despite its hurdles.

The motivation behind this project is to make our livelihood greener. The World is aware of

the fact that too much use of fossil fuels is making our environment corrupted,

simultaneously emptying the natural resources present on this earth. To tackle this problem,

this project has been specifically focused on one of the renewable energy sources supplied to

earth i.e. solar energy (sunlight). By converting solar energy to electrical energy during

daytime via the process of photovoltaic using solar cells which is totally eco-friendly and

using that electricity, street lights are powered up in the night and further their intensity is

controlled according to the sunlight as morning approaches or as evening approaches. Power

consumption is also one of the main focuses in this project and it is seen that the setup

requires much less power than that of its alternatives. As the basis of this project is set up on

a renewable energy source, maximum amount of power is saved taking the other electrical

components into consideration too.

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1.3 ORGANIZATION OF THE THESIS

In the thesis of the project, every simple aspect of it including the working principle, our

findings and researches, results, etc. are documented. For easier understanding, it is briefed.

Firstly description of the working principle of the complete model is stated. The Charge

stored using a solar panel is stored in a battery where the charge controller is an efficient

component which efficiently controls the input and output of a specified battery i.e. when the

battery gets fully charged and there is a problem of voltage overloading, it can cut charge

from its input and when low voltage is received, it can cut the load from its output. Here the

transistor works as a switch. Here in this project we consider when the voltage is less than 10

volts or equal to 10 volts, then controller cut out the load from the output of the battery. And

also when the battery voltage is greater or equal to 13 volt, then the controller can cut the

input of the battery from the solar panel. Then the battery is observed to be in discharging

mode. These were the findings on how the charge controlling section works during storage of

charge inside the battery. Another thing is auto intensity control. In this project we design a

automatic system that can control the on-off condition as well as different intensity of street

light. Here we use a series of led light to show different conditions. In the evening when the

entire led is not required to glow, in this time only a few led will glow. After getting dark at

night all led are glow. That is the auto intensity control. We also use an auto and manual

mode condition. When there is problem in LDR based circuit, we can choose the manual

mode. In this mode we can glow the light by manually. Otherwise the system is in auto mode.

When the battery is in low voltage condition it can be charged from solar or alternative

source (rectifier source). Suppose at night the battery is in low voltage condition, at this time

the load is automatically continued by the alternative supply (rectifier source).

3

CHAPTER- 2

B A S I C S T R U C T U R E

2.1 INTRODUCTION TO SMART STREET LIGHTING SYSTEM[Refer to No.01 under Section titled ‘References’]

The word "smart" has many different definitions and nuances; however, there is one common

denominator that ties them all together: it always represents something above average, an

added value or special capabilities.

Smart and intelligent street lighting control systems are designed primarily for energy

efficiency. A comprehensive system usually consists of advanced luminous sources such as

HID (High Intensity Discharge) or LED (Light-emitting diode) lamps, control unit and

sensor(s) installed in each lamp pole or group of lamp poles, communication units and a

management center application/ system. These components are connected through a reliable

and secured wired or wireless network that enables two way communications - for

monitoring and control functions. Smart street lighting control can also be connected to

conventional lights but then it may offer less energy efficiency and "smart" control, as

specified below. The intelligent system provides the operator with web access for automatic

or manual monitoring and control over illumination performance.

The benefits of this type of technology can be:

a) Energy savings: energy use and costs decline, because the lights dim as dawn approaches.

b) Maintenance cost reduction: maintenance costs are reduced because it takes more time

before the lamps have to be replaced.

c) Reduction in CO₂ emissions: with this energy reduction comes a reduction in CO₂

emissions.

d) Reduction of light pollution: light pollution is reduced, because the street lights don’t

shine at full brightness anymore. Street scenes become calmer looking.

e) Maintenance of safety: safety is maintained, because the lights are dimmed, not turned off

completely.

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2.2 CONVERSION OF SOLAR ENERGY TO ELECTRIC ENERGY[Refer to no. 02 under section titled ‘References’]

Fig: - 1 – Conversion of Solar Energy to Electric Energy

As we can see that the basic principle of solar conversion requires a solar panel or solar cell

for the conversion.

Light striking a silicon semiconductor causes electrons to flow, creating electricity. Solar

power generating systems take advantage of this property to convert sunlight directly into

electrical energy.

Solar panels (also called “solar modules”) produce direct current (DC), which goes through a

power inverter to become alternating current (AC) — electricity that we can use in the home

or office, like that supplied by a utility power company.

There are two types of solar power generating systems: grid-connected systems, which are

connected to the commercial power infrastructure; and stand-alone systems, which feed

electricity to a facility for immediate use, or to a battery for storage.

Grid-connected systems are used for homes, public facilities such as schools and hospitals,

and commercial facilities such as offices and shopping centers. Electricity generated during

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the daytime can be used right away, and in some cases surplus electricity can be sold to the

utility power company. If the system doesn’t generate enough electricity, or generates none at

all (for example, on a cloudy or rainy day, or at night) electricity is purchased from the utility

power company. Power production levels and surplus selling can be checked in real time on a

monitor, an effective way to gauge daily energy consumption.

Stand-alone systems are used in a variety of applications, including emergency power supply

and remote power where traditional infrastructure is unavailable.

Fig: - 2 – Working of solar cell

When sunlight hits the semiconductor, an electron springs up and is attracted to the n-type

semiconductor. This causes more negative electrons in the n-type semiconductor and more

positive electrons in the p-type, thus generating a flow of electricity in a process known as the

“photovoltaic effect.”

Fig: - 3 Solar Cell

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2.2 Some of Applications of solar energy[Refer to No.03 under section titled ‘References’]

1. Power plants: In conventional power plants non-renewable energy sources are used to boil

water and form stream so that turbines can rotate and water to produce electricity. But with

application of solar energy heat of sun can boil that water to create steam and rotate turbines.

To convert sunlight into electricity solar panels, photoelectric technologies and

thermoelectric technologies etc are used.

2. Homes: Use of solar energy is increasing in homes as well. Residential appliances can easily

use electricity generated through solar power. Besides this solar energy is running solar

heater to supply hot water in homes. Through photovoltaic cell installed on the roof of the

house energy is captured and stored on batteries to use throughout the day at homes for

different purposes. In this ways expenditure on energy is cutting down by home users.

3. Commercial use: on roofs of different buildings we can find glass PV modules or any other

kind of solar panel. These panels are used there to supply electricity to different offices or

other parts of building in a reliable manner. These panels collect solar energy from sun,

convert it into electricity and allow offices to use their own electrical power for different

purposes.

4. Ventilation system: at many places solar energy is used for ventilation purposes. It helps in

running bath fans, floor fans, and ceiling fans in buildings. Fans run almost every time in a

building to control moisture, and smell and in homes to take heat out of the kitchen. It can

add heavy amount on the utility bills, to cut down these bills solar energy is used for

ventilation purposes.

5. Power pump: solar power not just help in improving ventilation system at your homes but

with that it can also help in circulating water in any building. You can connect power pump

with solar power supply unit but you must run it on DC current so that water circulate

throughout your home.

6. Swimming pools: swimming pools are great joy for kids and adults in all seasons. But during

winters it is tough to keep water hot in these pools with minimum power usage. Solar energy

can help many in this matter as well. You can add a solar blanket in the pool that will keep

the water hot with energy generated from sunlight. Besides this you can install a solar hot

water heating system with solar hot water heating panels.

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7. Solar Lighting: these lights are also known as day lighting, and work with help of solar

power. These lights store natural energy of sun in day time and then convert this energy into

electricity to light up in night time. Use of this system is reducing load form local power

plants.

8. Solar Cars: it is an electrical vehicle which is recharged form solar energy or sunlight. Solar

panels are used on this car that absorb light and then convert it into electrical energy. This

electrical energy is stored in batteries used with the car, so that in night time as well we can

drive these vehicles.

9. Remote applications: Remote buildings are taking benefit of solar energy at vast scale.

Remote schools, community halls, and clinics can take solar panel and batteries with them

anywhere to produce and use electric power.

2.4 Solar Integrated Smart Street Lighting System[Refer to no. 04 under section titled ‘References’]

Fig.4 – Solar integrated smart street lights

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Solar street lights are raised light sources which are powered by photovoltaic panels generally

mounted on the lighting structure or integrated in the pole itself. The photovoltaic panels

charge a rechargeable battery, which powers a fluorescent or LED lamp during the night.

Components

Solar powered street lights

Solar street lights consist of 5 main parts:

A. Solar Panel - The solar panel is one of the most important parts of solar street lights, as

the solar panel will convert solar energy into electricity. Solar panel are varies from

wattage systems.

B. Lighting Fixture - LED is usually used as lighting source of modern solar street light, as

the LED will provide much higher Lumens with lower energy consumption. The energy

consumption of LED fixture is at least 50% lower than HPS fixture which is widely used

as lighting source in Traditional street lights. LEDs lack of warm up time also allows for

use of motion detectors for additional efficiency gains.

C. Rechargeable Battery - Battery will store the electricity from solar panel during the day

and provide energy to the fixture during night. The life cycle of the battery is very

important to the lifetime of the light and the capacity of the battery will affect the backup

days of the lights. There are usually 2 types of batteries: Gel Cell Deep Cycle Battery and

Lead Acid Battery and many more.

D. Controller - Controller is also very important for solar street light. A controller will

usually decide to switch on /off charging and lighting. Some modern controllers are

programmable so that user can decide the appropriate change of charging, lighting and

dimming.

E. Pole - Strong Poles are necessary to all street lights, especially to solar street lights as

there are often components mounted on the top of the pole: fixtures, panels and

sometimes batteries. However, in some newer designs, the PV panels and all electronics

are integrated in the pole itself. Wind resistance is also a factor.

Advantages

A. Solar street lights are independent of the utility grid. Hence, the operation costs are

minimized.

B. Solar street lights require much less maintenance compared to conventional street lights.

C. Since external wires are eliminated, risk of accidents is minimized.

D. This is a non-polluting source of electricity.

E. Separate parts of solar system can be easily carried to the remote areas.

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CHAPTER- 3

COMPONENTS ESSENTIAL FOR THE PROJECT

3.1 NPN Transistor[Refer to No.05 under section titled ‘References’]

A bipolar junction transistor (bipolar transistor or BJT) is a type of transistor that uses

both electron and hole charge carriers. In contrast, unipolar transistors, such as field-effect

transistors, only use one kind of charge carrier. For their operation, BJTs use two junctions

between two semiconductor types, n-type and p-type. BJTs are manufactured in two types,

NPN and PNP, and are available as individual components, or fabricated in integrated

circuits, often in large numbers. The basic function of a BJT is to amplify current. This

allows BJTs to be used as amplifiers or switches, giving them wide applicability in electronic

equipment, including, computers, televisions, mobile phones, audio amplifiers, industrial

control, and radio transmitters

Bipolar transistors have five distinct regions of operation, defined by BJT junction biases.

Forward-active (or simply, active): The base–emitter junction is forward biased and the

base–collector junction is reverse biased. Most bipolar transistors are designed to afford

the greatest common-emitter current gain, βF, in forward-active mode. If this is the case,

the collector–emitter current is approximately proportional to the base current, but many

times larger, for small base current variations.

Reverse-active (or inverse-active or inverted): By reversing the biasing conditions of

the forward-active region, a bipolar transistor goes into reverse-active mode. In this

mode, the emitter and collector regions switch roles. Because most BJTs are designed to

maximize current gain in forward-active mode, the βF in inverted mode is several times

smaller (2–3 times for the ordinary germanium transistor). This transistor mode is seldom

used, usually being considered only for failsafe conditions and some types of bipolar

logic. The reverse bias breakdown voltage to the base may be an order of magnitude

lower in this region.

Saturation: With both junctions forward-biased, a BJT is in saturation mode and

facilitates high current conduction from the emitter to the collector (or the other direction

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in the case of NPN, with negatively charged carriers flowing from emitter to collector).

This mode corresponds to a logical "on", or a closed switch.

Cutoff: In cutoff, biasing conditions opposite of saturation (both junctions reverse biased)

are present. There is very little current, which corresponds to a logical "off", or an open

switch.

Table: - 4.1- Mode of work of N-P-N Transistor

The modes of operation can be described in terms of the applied voltages (this description

applies to NPN transistors; polarities are reversed for PNP transistors)

Forward-active: base higher than emitter, collector higher than base (in this mode the

collector current is proportional to base current by ).

Saturation: base higher than emitter, but collector is not higher than base.

Cut-Off: base lower than emitter, but collector is higher than base. It means the transistor is

not letting conventional current go through from collector to emitter.

Reverse-active: base lower than emitter, collector lower than base: reverse conventional

current goes through transistor.

In terms of junction biasing: ('reverse biased base–collector junction' means Vbc< 0 for NPN,

opposite for PNP)

Although these regions are well defined for sufficiently large applied voltage, they overlap

somewhat for small (less than a few hundred mili volts) biases. For example, in the typical

grounded-emitter configuration of an NPN BJT used as a pull down switch in digital logic,

the "off" state never involves a reverse-biased junction because the base voltage never goes

below ground; nevertheless the forward bias is close enough to zero that essentially no

current flows, so this end of the forward active region can be regarded as the cutoff region.

Applied voltages B-E junction

bias (NPN)

B-C junction

bias (NPN)

Mode (NPN)

E < B < C Forward Reverse Forward-active

E < B > C Forward Forward Saturation

E > B < C Reverse Reverse Cut-off

E > B > C Reverse Forward Reverse-active

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3.1.1 Active-mode NPN transistors in circuits

Fig: - 5 – Structure and Use of NPN transistor

The diagram shows a schematic representation of an NPN transistor connected to two voltage

sources. To make the transistor conduct appreciable current (on the order of 1 mA) from C to

E, VBE must be above a minimum value sometimes referred to as the cut-in voltage. The cut-

in voltage is usually about 650 mV for silicon BJTs at room temperature but can be different

depending on the type of transistor and its biasing. This applied voltage causes the lower P-N

junction to 'turn on', allowing a flow of electrons from the emitter into the base. In active

mode, the electric field existing between base and collector (caused by VCE) will cause the

majority of these electrons to cross the upper P-N junction into the collector to form the

collector current IC. The remainder of the electrons recombines with holes, the majority

carriers in the base, making a current through the base connection to form the base current, IB.

As shown in the diagram, the emitter current, IE, is the total transistor current, which is the

sum of the other terminal currents, (i.e., IE = IB + IC).

In the diagram, the arrows representing current point in the direction of conventional

current – the flow of electrons is in the opposite direction of the arrows because electrons

carry negative electric charge. In active mode, the ratio of the collector current to the base

current is called the DC current gain. This gain is usually 100 or more, but robust circuit

designs do not depend on the exact value (for example see op-amp). The value of this gain for

DC signals is referred to as H fe, and the value of this gain for small signals is referred to

as H fe That is, when a small change in the currents occurs, and sufficient time has passed for

the new condition to reach a steady state H fe is the ratio of the change in collector current to

the change in base current. The symbol β is used for both H fe and H fe.[9]

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The emitter current is related to VBE exponentially. At room temperature, an increase

in VBE by approximately 60 mV increases the emitter current by a factor of 10. Because the

base current is approximately proportional to the collector and emitter currents, they vary in

the same way.

Fig: - 6 – Avalanche Breakdown Region

A Bipolar NPN Transistor Configuration

Fig: - 7 – Configuration of NPN Transistor

(Note: Arrow defines the emitter and conventional current flow, “out” for a Bipolar NPN

Transistor.)

The construction and terminal voltages for a Bipolar NPN Transistor are shown above. The

voltage between the Base and Emitter ( VBE ), is positive at the Base and negative at the

Emitter because for an NPN transistor, the Base terminal is always positive with respect to

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the Emitter. Also the Collector supply voltage is positive with respect to the Emitter (VCE ).

So for a bipolar NPN transistor to conduct the Collector is always more positive with respect

to both the Base and the Emitter.

Fig: - 8 - NPN Transistor Connection

Then the voltage sources are connected to an NPN transistor as shown. The Collector is

connected to the supply voltage VCC via the load resistor, RL which also acts to limit the

maximum current flowing through the device. The Base supply voltage VB is connected to

the Base resistor RB, which again is used to limit the maximum Base current.

So in a NPN Transistor it is the movement of negative current carriers (electrons) through the

Base region that constitutes transistor action, since these mobile electrons provide the link

between the Collector and Emitter circuits. This link between the input and output circuits is

the main feature of transistor action because the transistors amplifying properties come from

the consequent control which the Base exerts upon the Collector to Emitter current.

Then we can see that the transistor is a current operated device (Beta model) and that a large

current (I C) flows freely through the device between the collector and the emitter terminals

when the transistor is switched “fully-ON”. However, this only happens when a small biasing

current ( I B ) is flowing into the base terminal of the transistor at the same time thus allowing

the Base to act as a sort of current control input.

The transistor current in a bipolar NPN transistor is the ratio of these two currents ( I C /I B ),

called the DC Current Gain of the device and is given the symbol of H fe or nowadays Beta

(β). The value of β can be large up to 200 for standard transistors, and it is this large ratio

betweenI C and I B that makes the bipolar NPN transistor a useful amplifying device when

used in its active region as I B provides the input and I Cprovides the output. Note

that Beta has no units as it is a ratio.

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Also, the current gain of the transistor from the Collector terminal to the Emitter terminal, I C /

I E, is called Alpha ( α ), and is a function of the transistor itself (electrons diffusing across the

junction). As the emitter currentI E is the sum of a very small base current plus a very large

collector current, the value of alpha α, is very close to unity, and for a typical low-power

signal transistor this value ranges from about 0.950 to 0.999.

DC Current Gain=Output CurrentInput Current

=I C

I B

I E=I B+ I C……… (KCL) And I C

IE=α

Thus, I B=I E−IC

I B=I E−α IE

I B=I E(1−α)

i.e. β=IC

I B=

IC

I E(1−α)= α

1−α

By combining the two parameters α and β we can produce two mathematical expressions that

give the relationship between the different currents flowing in the transistor.

α= ββ+1

∨α=β (1−α)

β= α1−α

∨β=α (1+ β )

If,

α = 0.99 and β = 0.990.01

=99

The values of Beta vary from about 20 for high current power transistors to well over 1000

for high frequency low power type bipolar transistors. The value of Beta for most standard

NPN transistors can be found in the manufactures data sheets but generally range between 50

and 200.

The equation above for Beta can also be re-arranged to make I C as the subject, and with a

zero base current (I B = 0 ) the resultant collector current I C will also be zero, ( β x 0 ). Also

when the base current is high the corresponding collector current will also be high resulting

in the base current controlling the collector current. One of the most important properties of

the Bipolar Junction Transistor is that a small base current can control a much larger collector

current.

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In this project BC547 transistor is used.

Fig: - 9 – Symbol of BC547

3.1.2 BC547 Transistor Specification[Refer to No.06 under section titled ‘References’]

Datasheet and Parameters -

Type Designator: BC547

Material of transistor: Si

Polarity: NPN

Maximum collector power dissipation (Pc), W : 0.5

Maximum collector-base voltage (V cb), V : 50

Maximum collector-emitter voltage (V ce), V : 50

Maximum emitter-base voltage (V eb), V : 6

Maximum collector current (I C max), A : 0.1

Maximum temperature (T j),°C : 150

Transition frequency ( ft ), MHz : 300

Collector capacitance (CC), pF : 6

Forward current transfer ratio (H fe), min : 110

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SPECFICATION IN DETAILS

1. Power Ratings-

The rated power dissipation for transistors is the total power developed across both junctions

of the transistor that will raise the internal temperature to the maximum permitted (i.e. not

something that should be maintained in normal use), and will be specified for a given ambient

temperature for low-power transistors such as these, in this case 25 degrees Celsius. In

practice factors such as the proximity of the transistor to the printed circuit board will

influence how well heat can be removed from the transistor and proximity to other heat-

generating components will increase the ambient temperature - and probably reduce the

permissible dissipation below the 500-625 mW ideal-conditions specification.

2. Voltage ratings-

The BC547 and BC548, and their PNP counterparts (BC558 and BC559) can be used in

circuits where voltages reach no more than 30 Volts, limited mainly by their VCEO rating. The

VCBO rating refers to the maximum voltage between collector and base with the emitter open-

circuit (not typical operation), and their predecessors, the BC108 and BC109, while having

VCBO or VCES ratings of 30 V have only a 20 VCEO) rating, meaning a BC548 (or BC549) can

replace a BC108 but a BC108 might not be a safe replacement for a BC148.

3. Variants-

The BC546 and BC547 have higher voltage ratings; the BC549 has lower noise, and the

BC550 has both higher voltage and lower noise, and the last digit of the type number follows

a pattern common to several other transistors tabulated for the BC108 family of transistors.

Some manufacturers specify their parts with higher ratings, for example the Fairchild 1997

datasheet (547ABC, Rev B) for the BC547, sourced from Process 10 gave 500mA as the

maximum collector current, and while their datasheets dated 2002 have dropped the current

rating to the standard 100mA.

PNP Versions of BC547-The PNP counterparts of the BC546 to BC550 are the BC556 to

BC560 respectively, i.e. the type numbers are higher by ten.

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[Refer to No.07under section titled ‘References’](applicable up to 3.11)

3.2 DIODEIn electronics, a diode is a two-terminal electronic component that conducts primarily in one

direction (asymmetric conductance); it has low (ideally zero) resistance to the flow

of current in one direction, and high (ideally infinite) resistance in the other. 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.[5] A vacuum tube diode has

two electrodes, a plate (anode) and a heated cathode. Semiconductor diodes were the first

semiconductor electronic devices. The discovery of crystals' rectifying abilities was made by

German physicist Ferdinand Braun in 1874. The first semiconductor diodes, called cat's

whisker diodes, developed around 1906, were made of mineral crystals such as galena.

Today, most diodes are made of silicon, but other semiconductors such

as selenium or germanium are sometimes used.

Types of semiconductor Diode

There are several types of p–n junction diodes, which emphasize either a different physical

aspect of a diode often by geometric scaling, doping level, choosing the right electrodes, are

just an application of a diode in a special circuit, or are really different devices like the Gunn

and laser diode and the MOSFET:

Normal (p–n) diodes, which operate as described above, are usually made of doped silicon or,

more rarely, germanium. Before the development of silicon power rectifier diodes, cuprous

oxide and later selenium was used. Their low efficiency required a much higher forward

voltage to be applied (typically 1.4 to 1.7 V per "cell", with multiple cells stacked so as to

increase the peak inverse voltage rating for application in high voltage rectifiers), and

required a large heat sink (often an extension of the diode's metal substrate), much larger than

the later silicon diode of the same current ratings would require. The vast majority of all

diodes are the p–n diodes found in CMOS integrated circuits, which include two diodes per

pin and many other internal diodes.

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Fig: - 10 – Diodes (IN4007)

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

Fig: - 11 – LED

3.4 ELECTRICAL CONNECTORAn electrical connector is an electro-mechanical device for joining electrical circuits as an

interface using a mechanical assembly. Connectors consist of plugs (male-ended) and jacks

(female-ended). The connection may be temporary, as for portable equipment, require a tool

for assembly and removal, or serve as a permanent electrical joint between two wires or

devices. An adapter can be used to effectively bring together dissimilar connectors.

There are hundreds of types of electrical connectors. Connectors may join two lengths of

flexible copper wire or cable, or connect a wire or cable to an electrical terminal. Side bind

connectors are used in the project.

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Fig: - 12 – Electrical Connector

3.5 VOLTAGE REGULATOR (IC 7812)A voltage regulator is one of the most widely used electronic circuitry in any device. A

regulated voltage (without fluctuations & noise levels) is very important for the smooth

functioning of many digital electronic devices. A common case is with micro controllers,

where a smooth regulated input voltage must be supplied for the micro controller to function

smoothly.

Voltage regulators are of different types. In this article, our interest is only with IC based

voltage regulator. An example of IC based voltage regulator available in market is the

popular 7805 IC which regulates the output voltage at 5 volts. Now let’s come to the basic

definition of an IC voltage regulator. It is an integrated circuit whose basic purpose is to

regulate the unregulated input voltage (definitely over a predefined range) and provide with a

constant, regulated output voltage.

An IC based voltage regulator can be classified in different ways. A common type of

classification is 3 terminal voltage regulator and 5 or multi terminal voltage regulator.

Another popular way of classifying IC voltage regulators is by identifying them as linear

voltage regulator & switching voltage regulator. There is a third set of classification as 1)

Fixed voltage regulators (positive & negative) 2) Adjustable voltage regulators (positive &

negative) and finally 3) Switching regulators. In the third classification, fixed & adjustable

regulators are basically versions of linear voltage regulators.

Fixed Voltage Regulators

These regulators provide a constant output voltage. A popular example is the 7805 IC which

provides a constant 5 volts output. A fixed voltage regulator can be a positive voltage

regulator or a negative voltage regulator. A positive voltage regulator provides with constant

positive output voltage. All those IC’s in the 78XX series are fixed positive voltage

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regulators. In the IC nomenclature – 78XX; the part XX denotes the regulated output voltage

the IC is designed for. Examples: - 7805, 7806, 7809 etc.

A negative fixed voltage regulator is same as the positive fixed voltage regulator in design,

construction & operation. The only difference is in the polarity of output voltages. These IC’s

are designed to provide a negative output voltage. Example: - 7905, 7906 and all those IC’s

in the 79XX series.

Fig: - 13 – Regulators (7812)

Adjustable Voltage Regulator

An adjustable voltage regulator is a kind of regulator whose regulated output voltage can be

varied over a range. There are two variations of the same; known as positive adjustable

voltage regulator and negative adjustable regulator. LM317 is a classic example of positive

adjustable voltage regulator, whose output voltage can be varied over a range of 1.2 volts to

57 volts. LM337 is an example of negative adjustable voltage regulator. LM337 is actually a

complement of LM317 which are similar in operation & design; with the only difference

being polarity of regulated output voltage.

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Fig: - 14 – Adjustable Voltage Regulator (LM317)

3.6 TRANSFORMER (230V/12V, 1Amp, 12VA)Electrical power transformer is a static device which transforms electrical energy from one

circuit to another without any direct electric connection and with the help of mutual induction

between two windings. It transforms power from one circuit to another without changing its

frequency but may be in different voltage level.

A transformer is made of a soft iron coil with two other coils wound around it, but not

connected with one another. The iron coils can either be arranged on top of another or be

wound on separate limps of the iron core. The coil to which the alternating voltage is

supplied is known as primary winding or primary coil while. The alternating current in the

primary winding produces a changing magnetic field around it whenever an alternating

potential is supplied. An alternating current is in turn produced by the changing field in the

secondary coil and the amount of current produced depends on the number of windings in the

secondary coil. There are two types of transformers, namely: Step down and Step up

transformers. Generally, the difference between them is the amount of voltage produced,

depending on the number of secondary coils. A transformer is made of a soft iron coil with

two other coils wound around it, but not connected with one another. The iron coils can either

be arranged on top of another or be wound on separate limps of the iron core. The coil to

which the alternating voltage is supplied is known as primary winding or primary coil while.

The alternating current in the primary winding produces a changing magnetic field around it

whenever an alternating potential is supplied. An alternating current is in turn produced by

22

the changing field in the secondary coil and the amount of current produced depends on the

number of windings in the secondary coil. There are two types of transformers, namely: Step

down and Step up transformers. Generally, the difference between them is the amount of

voltage produced, depending on the number of secondary coils.

Step-Down Transformer

The relationship between the voltage and the number of turns in each coil

is given by –

Voltage∈Secondary CoilVoltage∈Primary Coil

=Turns on Secondary CoilTurns on PrimaryCoil

Or

V S

V P=

N S

NP

When V Sis less thanV P,that means the transformer is a step down transformer.

A step down transformer has less turns on the secondary coil than the primary coil. The

induced voltage across the secondary coil is less the applied voltage across the primary coil

or in other words the voltage is “stepped-down”.

23

Fig: - 15 - Transformer

In fig: 17 we can see a step down transformer which is used in our project. This transformer

has the following ratings- 230V/12V, 1 Amp, 12 VA. In this project the transformer is used

for the purpose of emergency backup system. A rectifier circuit is used the transformer for

getting DC output.

3.7 RESISTORS, POTENTIOMETER, CAPACITORS AND RELAY

3.7.1 Resistors (10K, 1K & 100K)A resistor is a passive two-terminal electrical component that implements electrical resistance

as a circuit element. Resistors act to reduce current flow, and, at the same time, act to lower

voltage levels within circuits. In electronic circuits, resistors are used to limit current flow, to

24

adjust signal levels, bias active elements, and terminate transmission lines among other uses.

High-power resistors, that can dissipate many watts of electrical power as heat, may be used

as part of motor controls, in power distribution systems, or as test loads for generators. Fixed

resistors have resistances that only change slightly with temperature, time or operating

voltage. Variable resistors can be used to adjust circuit elements (such as a volume control or

a lamp dimmer), or as sensing devices for heat, light, humidity, force, or chemical activity.

Resistors are common elements of electrical networks and electronic circuits and are

ubiquitous in electronic equipment. Practical resistors as discrete components can be

composed of various compounds and forms. Resistors are also implemented within integrated

circuits.

The electrical function of a resistor is specified by its resistance: common commercial

resistors are manufactured over a range of more than nine orders of magnitude. The nominal

value of the resistance will fall within a manufacturing tolerance.

Fig: - 16 – Resistance (1K)

The resistor colour codes in 1K resistor are:-

1. Brown

2. Black

3. Red

4. Gold

The value stands at 10k Ohms with tolerance 5%.

3.7.2 Potentiometer (10K)A potentiometer, informally a pot, is a three-terminal resistor with a sliding or rotating con

tact 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.

25

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 control.

Fig: - 17 – Potentiometer (10K)

3.7.3 Capacitors (470uF, 0.1uF)A capacitor (originally known as a condenser) is a passive two-terminal electrical

component used to store electrical energy temporarily in an electric field. The forms of

practical capacitors vary widely, but all contain at least two electrical conductors(plates)

26

separated by a dielectric (i.e. an insulator that can store energy by becoming polarized). The

conductors can be thin films, foils or sintered beads of metal or conductive electrolyte, etc.

The non-conducting dielectric acts to increase the capacitor's charge capacity. A dielectric

can be glass, ceramic, plastic film, air, vacuums, paper, mica, oxide layer etc. Capacitors are

widely used as parts of electrical circuits in many common electrical devices. Unlike

a resistor, an ideal capacitor does not dissipate energy. Instead, a capacitor stores energy in

the form of an electrostatic field between its plates.

When there is a potential difference across the conductors (e.g., when a capacitor is attached

across a battery), an electric field develops across the dielectric, causing

positive charge +Q to collect on one plate and negative charge −Q to collect on the other

plate. If a battery has been attached to a capacitor for a sufficient amount of time, no current

can flow through the capacitor. However, if a time-varying voltage is applied across the leads

of the capacitor, a displacement current can flow.

The larger the surface area of the "plates" (conductors) and the narrower the gap between

them, the greater the capacitance is. In practice, the dielectric between the plates passes a

small amount of leakage current and also has an electric field strength limit, known as the

breakdown voltage. The conductors and leads introduce an undesired inductance and

resistance.

Capacitors are widely used in electronic circuits for blocking direct current while

allowing alternating current to pass. In filter networks, they smooth the output of power

supplies. In resonant circuits they tune radios to particular frequencies. In electric power

transmission systems, they stabilize voltage and power flow.

Fig: - 18 - Capacitors (470uf)

3.7.3 RelayWhat is a relay?

We know that most of the high end industrial application devices have relays for their

effective working. Relays are simple switches which are operated both electrically and

27

mechanically. Relays consist of a n electromagnet and also a set of contacts. The switching

mechanism is carried out with the help of the electromagnet. There are also other operating

principles for its working. But they differ according to their applications. Most of the devices

have the application of relays.

Why is a relay used?

The main operation of a relay comes in places where only a low-power signal can be used to

control a circuit. It is also used in places where only one signal can be used to control a lot of

circuits. The application of relays started during the invention of telephones. They played an

important role in switching calls in telephone exchanges. They were also used in long

distance telegraphy. They were used to switch the signal coming from one source to another

destination. After the invention of computers they were also used to perform Boolean and

other logical operations. The high end applications of relays require high power to be driven

by electric motors and so on. Such relays are called contactors.

Different Types of Relay:-

Relays are remote control electrical switches that are controlled by another switch, such as a

horn switch or a computer as in a power train module. Relays allow a small current flow

circuit to control a higher current circuit. Several designs of relays are in use today, 3-pin, 4-

pin, 5-pin, and 6- pin, single switch or dual switches. Relays which come in various sizes,

ratings, and applications, are used as remote control switches. Fig. 5 shows different types of

relays. In this paper, the 4-pin relay will be used.

28

Fig: - 19 – Different types of Relay

Relay Construction:-

It is an electro-magnetic relay with a wire coil, surrounded by an iron core. A path of very

low reluctance for the magnetic flux is provided for the movable armature and also the switch

point contacts. The movable armature is connected to the yoke which is mechanically

connected to the switch point contacts. These parts are safely held with the help of a spring.

The spring is used so as to produce an air gap in the circuit when the relay becomes de-

energized.

Application of Relay

Selection of an appropriate relay for a particular application requires evaluation of many

different factors:

Number and type of contacts – normally open, normally closed, (double-throw)

Contact sequence – "Make before Break" or "Break before Make". For example, the old

style telephone exchanges required Make-before-break so that the connection didn't get

dropped while dialing the number.

Contact current rating – small relays switch a few amperes, large contactors are rated for

up to 3000 amperes, alternating or direct current.

Contact voltage rating – typical control relays rated 300 VAC or 600 VAC, automotive

types to 50 VDC, special high-voltage relays to about 15,000 V.

Operating lifetime, useful life - the number of times the relay can be expected to operate

reliably. There is both a mechanical life and a contact life. The contact life is affected by

the type of load switched. Breaking load current causes undesired arcing between the

contacts, eventually leading to contacts that weld shut or contacts that fail due erosion by

the arc.

Coil voltage – machine-tool relays usually 24 VDC, 120 or 250 VAC, relays for

switchgear may have 125 V or 250 VDC coils.

Coil current - Minimum current required for reliable operation and minimum holding

current, as well as, effects of power dissipation on coil temperature, at various duty

cycles. "Sensitive" relays operate on a few mili amperes.

Package/enclosure – open, touch-safe, double-voltage for isolation between

circuits, explosion proof, outdoor, oil and splash resistant, washable for printed

circuit board assembly.

29

Fig: - 20 - Relay (12V)

3.8 – LDR (LIGHT DEPENDENT RESISTOR)

A 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.

Fig: - 21 - LDR

30

3.8.1 - Working 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 and it is shown in figure.

Fig: - 22 – Working of LDR

3.8.2 - Characteristics of LDRLDR’s are light dependent devices whose resistance decreases when light falls on them and

increases in the dark. When a light dependent resistor is kept in dark, its resistance is very

high. This resistance is called as dark resistance. It can be as high as 1012 Ω. And if the

device is allowed to absorb light its resistance will decrease drastically. If a constant voltage

is applied to it and intensity of light is increased the current starts increasing. Figure below

shows resistance vs. illumination curve for a particular LDR.

31

Fig: - 23(a) – Characteristics of LDR

Photocells or LDR’s are non-linear devices. There sensitivity varies with the wavelength of

light incident on them. Some photocells might not at all response to a certain range of

wavelengths. Based on the material used different cells have different spectral response

curves.

When light is incident on a photocell it usually takes about 8 to 12ms for the change in

resistance to take place, while it takes seconds for the resistance to rise back again to its

initial value after removal of light. This phenomenon is called as resistance recovery rate.

This property is used in audio compressors. Also, LDR’s are less sensitive than photo diodes

and photo transistor. (A photo diode and a photocell (LDR) are not the same, a photo-diode is

a p-n junction semiconductor device that converts light to electricity, whereas a photocell is a

passive device, there is no p-n junction in this nor it “converts” light to electricity).

32

Fig: - 23(b) – Characteristics of LDR

The most common type of LDR has a resistance that falls with an increase in the light

intensity falling upon the device (as shown in the graph). The resistance of an LDR may

typically have the following resistances:

• Daylight = 5000 ohms

• Dark = 20000000 ohms

3.8.3 - Types of Light Dependent Resistors:

Based on the materials used they are classified as:

i) Intrinsic photo resistors (Undoped semiconductor): These are pure semiconductor materials

such as silicon or germanium. Electrons get excited from valance band to conduction band

when photons of enough energy falls on it and number charge carriers increases.

ii) Extrinsic photo resistors: These are semiconductor materials doped with impurities which

are called as dopants. Theses dopants create new energy bands above the valence band which

are filled with electrons. Hence this reduces the band gap and less energy is required in

exciting them. Extrinsic photo resistors are generally used for long wavelengths.

3.8.4 - Applications of LDR

LDR’s have low cost and simple structure.

Fig: - 25 – Construction of Photocell

33

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 and burglar alarm circuits.

Used in light intensity meters, for counting the packages moving on a conveyor belt, etc.

Fig: - 24 – Types of LDR

3.9 Construction of a PhotocellThe structure of a light dependent resistor consists of a light sensitive material which is

deposited on an insulating substrate such as ceramic. The material is deposited in zigzag

pattern in order to obtain the desired resistance & power rating.

What is a Photoconductive Cell?

Semiconductor light detectors can be divided into two major categories: junction and bulk

effect devices. Junction devices, when operated in the photoconductive mode, utilize the

reverse characteristic of a PN junction. Under reverse bias, the PN junction acts as a light

controlled current source. Output is proportional to incident illumination and is relatively

independent of implied voltage as shown in Figure 1. Silicon photodiodes are examples of

this type detector.

Why Use Photocells?

Photocells can provide a very economic and technically

superior solution for many applications where the

Fig: - 26 – Double Pole Switch Fig: - 27 – Triple Pole Switch

34

presence or absence of light is sensed (digital operation) or where the intensity of light needs

to be measured (analog operation). Their general characteristics and features can be

summarized as follows: Lowest cost available and near-IR photo detector • Available in low

cost plastic encapsulated packages as well as hermetic packages (TO-46, TO-5, TO-8).

Responsive to both very low light levels (moonlight) and to very high light levels (direct

sunlight). Wide dynamic range: resistance changes of several orders of magnitude between

"light" and "no light" • Low noise distortion. Maximum operating voltages of 50 to 400 volts

are suitable for operation on 120/240 VAC. Available in center tap dual cell configurations as

well as specially selected resistance ranges for special applications. Easy to use in DC or AC

circuits - they are a light variable resistor and hence symmetrical with respect to AC

waveforms. Usable with almost any visible or near infrared light

3.10 DOUBLE POLE & TRIPLE POLE SWITCH

In electrical engineering, a switch is an electrical component that can break an electrical

circuit, interrupting the current or diverting it from one conductor to another. The mechanism

of a switch may be operated directly by a human operator to control a circuit (for example, a

light switch or a keyboard button), may be operated by a moving object such as a door-

operated switch, or may be operated by some sensing element for pressure, temperature or

flow.

There are various kinds of switches with terminologies relating to Pole and Throw. Double

pole - double throw and triple pole double throw switch is used for this project.

Fig: - 28 – Solar Panel

35

3.11 – SOLAR PANEL AND BATTERY

3.11.1 – Solar Panel

Solar panel refers to a panel designed

to absorb the sun's rays as a source of

energy for generating electricity or

heating.

A photovoltaic (in short PV) module is

a packaged, connected assembly of

typically 6×10 solar cells. Solar

Photovoltaic panels constitute the solar

array of a photovoltaic system that

generates and supplies solar electricity

in commercial and residential

applications. Each module is rated by

its DC output power under standard

test conditions, and typically ranges

from 100 to 365 watts. The efficiency

of a module determines the area of a module given the same rated output – an 8% efficient

230 watt module will have twice the area of a 16% efficient 230 watt module. There are a

few solar panels available that are exceeding 19% efficiency. A single solar module can

produce only a limited amount of power; most installations contain multiple modules. A

photovoltaic system typically includes a panel or an array of solar modules, a solar inverter,

and sometimes a battery and/or solar tracker and interconnection wiring.

36

Fig: - 29 – Specifications of Solar Panel

37

3.11.2 – Battery

An electric battery is a device consisting of one or more electrochemical cells with external

connections provided to power electrical devices. A discharging battery has a positive

terminal, or cathode, and a negative terminal, or anode. The terminal marked negative is the

source of electrons that when connected to an external circuit will flow and deliver energy to

an external device. When a battery is connected to an external circuit, electrolytes are able to

move as ions within, allowing the chemical reactions to be completed at the separate

terminals and so deliver energy to the external circuit. It is the movement of those ions within

the battery which allows current to flow out of the battery to perform work.

Fig: - 30 - 12V Battery

Fig: - 31 – Specifications of Battery

38

CHAPTER- 4I M P L E M E N T A T I O N

4.1 – CHARGE CONTROLLING CIRCUIT

Description: - Charge Controller is generally made for battery protection. It is a controlling

circuit that controls input and output of a battery. That means when the battery is fully

charged this circuit can cut charge from its input and when the voltage is low this circuit can

cut the load from its output. In Fig: - 32 we see a circuit of charge controller. This circuit

controls the battery output and input at various conditions.

Fig: - 32 – Circuit Diagram of Charge Controller

Here the transistor works as a switch. When the voltage is less than 10 volt or equal to 10

volt, the base-emitter voltage of transistor Q1 is less than 0.7 volt. So, the transistor is not

biased and the relay is in unenergized condition. That means the battery is now in unloaded

condition from its loaded condition. Again when the battery voltage is greater than 10 volt the

transistor is biased and the relay is energized. So the battery is again connected to load. In

those above conditions the battery is always in charging mode. When the battery voltage is

39

above 13 volt, transistor Q4 is biased because of getting base-emitter voltage. For this the

relay is in energized mood and it cut the solar input to the battery. The battery is now in

discharging mode. In fig: - 34, we see the fabrication of charge controlling circuit. This

circuit is connected between the solar panel and battery, as well as between the load and

battery. In this case we also use some indication when the battery is charging, when the

battery is full charged and when the battery is low voltage. Battery is a sensitive device and

very much important device for this project. If it is damaged for overcharging by over voltage

or being used in low voltage condition over a few days, the whole system will be in break

down condition and the whole system will be run in emergency condition. So, charge

controller has some useful applications for battery protection.

Fig: - 33 – Fabrication of Charge Controller

4.2 LDR BASED CIRCUIT

40

Description: - A 12volt supply is given to the circuit from battery. The transistor is totally

control the circuit behavior. Transistor is conducting when the base to emitter voltage is

greater than 0.7 volt. When torch light is very close to LDR, then the LDR behave as short

circuit path. So the transistor cannot conduct. So the LED is off. But when torch light is far

away from LDR, then the LDR behave as a high resistance and then the transistor get a base

emitter voltage. When transistor is in conducting mode the LED is on. Here we use three step

of this circuit for auto intensity control. That means the light intensity is increased according

to the increase of night from evening. For this we are used three level of resistance.

Fig: - 34 – Circuit Diagram of LDR Based Circuit

41

Fig: - 35 – Fabrication of LDR Based Circuit

In fig: - 35 we see that the fabrication of the LDR based circuit. We can see that how the

component of this circuit is used in this project.

42

4.3 ALTERNATIVE POWER SUPPLY

Description: - It is an emergency or alternative power supply. When the battery voltage goes

very low at night the charge controller is cut the load from battery. For this condition

alternative source is present there. In fig: - 37, a transformer is used for converting the 230

volt AC supply to 12 volt AC. Then a bridge converter is used for getting DC output from

AC input. Then filter is used for getting ripple free output. Then we use a 7812 voltage

regulator for getting pure and constant 12 volt DC output. Then this is used as a power

supply.

Fig: - 36 – Circuit Diagram of Alternative Power Supply

Fig: - 37 – Fabrication of Alternative Power Supply

43

4.4 CIRCUIT DIAGRAM OF CONTROLLING CIRCUIT

Fig: - 38 – Circuit Diagram of Controlling Circuit

Description: - Fig: - 37 is showing the controlling circuit of this project. As earlier, already

discuss about the working of charge controller. When the battery voltage is below 10 volt or

equals to 10 volt the relay 1 is in un energized condition. The relay is now in its NC

(normally closed) contact. Now a 3 volt supply is present in common point of the relay from

battery through a divider circuit. Now this 3 volt supply is only gone to another circuit when

relay 1 is in NC contact. This 3 volt supply will activate two transistors. One transistor is

used for an indication of low voltage. And the other one is pick up the relay 2. The relay 2

will connected to rectifier source when it is energized. That means when the low voltage is

sensed the load is connected to rectifier source through this relay 2. The common point of

relay 2 is connected to double pole two way switch. This is another control circuit. When the

circuit is in automatic condition, this switch will be in auto mode. But when the LDR circuit

44

is not working, the switch is in manual mode. In this manual mode another three pole 2 way

switch is connected. This switch is then used to glow the led. The relay 3 is energized when

the battery voltage is equal to or greater than 13 volt. That means the battery is fully charged.

For this condition another led is used for the indication of fully charged. When relay 3 is in

unenergized condition that means the battery is in charging mode, the NC contact is

connected to a double pole two way switch. This switch is used for whether the battery is

charging through solar or through rectifier source. This is the working principle of controlling

circuit of this project.

Fig: - 39 – Fabrication of controlling circuit

45

4.5 – FABRICATION OF COMPLETE PROJECT

46

Fig: - 40 – Fabrication of Project

47

CHAPTER- 5CONCLUSION AND FUTURE SCOPE

After the overall completion of our project we can conclude the following aspects:

I. Solar integrated SMART street lighting system is one of the leading innovations in the

21st century as it is not only eco-friendly but also more energy efficient.

II. Automatic controlling by various components and methods like charge controller and

2-pole switch leads to more energy conservation/lesser energy losses.

III. As they are automatically controlled using a timer, dimming and brightening are the

key points of the SMART street lights.

IV. The governments of different countries should initiate this type of solar integrated

projects to further promote a healthy environment for humans as it is pollution free.

The project is aimed towards creating an eco-friendly society for the citizens by

automatically induced SMART street lights using solar energy i.e. with respect to the sun’s

position the street lights will work. The street lights will start to dim towards dawn,

ultimately going off as day occurs and conversely the lights will start to brighten at the

evening, fully turning on as night occurs. This is the core aim of this project (demonstrating

the process of it). These are one of the most desired intelligent street lighting systems in the

world keeping the benefit of the common people in mind.

The initial investment in solar LED street light system remains a major problem. However,

the efficiency of the solar cells is increasing, while the price is decreasing. At same time, the

efficiency of the LED light is in a rapid increase, but the prices are lower. So following

development of the outdoor lighting technique, the solar LED street light system has shown

us that it will have promising applications and infinite vitality in future.

We can use dual axis solar tracker for efficient charging of battery from solar. It also helps to

generate more power from solar. If we want to increase the load this will be one of the most

efficient method.

48

APPENDIXI. Specifications of the required electrical components

Charge Controller:

Equipments Quantity Specifications

POT 2 10KΩ

NPN Transistor 2 BC547

Relay 2 12V

Resistor 4 1KΩ, 1KΩ, 500 Ω, 500 Ω

Connector 2 -

LDR Based Circuit:

Equipments Quantity Specifications

Light Dependent Resistor 3 -

Resistor 5 50KΩ, 150KΩ, 20 KΩ ,1KΩ, 1KΩ

Relay 3 12V

NPN Transistor 3 BC547

LED 3 -

Connector 3 -

Alternative Power Supply:

Equipments Quantity Specifications

Transformer 1 1 Amp,

Capacitor 2 1000μF, 470μF

Diode 4 IN4007

Voltage Regulator 1 IC7812

49

Controlling Circuit:

Equipments Quantity Specifications

NPN Transistor 2 BC547

Relay 1 12V

Double Pole 2-Way Switch 2 1Amp, 1Amp

Triple Pole 2-Way Switch 1 1Amp

Resistor 3 10KΩ, 10KΩ, 10KΩ

LED 3 -

50

II. Essentiality of Proteus in the project

About Proteus

[Reference - http://www.labcenter.com/]

Proteus is a software technology that allows creating clinical executable decision support

guidelines with little effort.

A software tool that allows creating and executing clinical decision Proteus is an ambitious

approach with a potential to touch many aspects of healthcare. Several prototype software

tools developed have validated the core features of the Proteus approach. The experience of

development carried out to date suggests that a more exhaustive implementation be created

and tested with healthcare professionals.

Proteus has helped us in the completion of the project technically in recreating the design of

the circuit and simultaneously checking for errors in any kind of wirings and other important

factors like voltage drops and led tests. Without Proteus it would’ve been impossible to

design the overall circuit as any kind of errors can be pre-checked to be sure for the final

design.

51

REFERENCES1. Smart Street Lighting (www.telematics-wireless.com)

2. Baldwin, Sam, Energy Efficiency & Renewable Energy: Challenges and Opportunities. Clean Energy Super

Cluster Expo Colorado State University. U.S. Department of Energy, 20 April 2011

3. Energy Sources – Types Of Energy Sources (www.solarpowernotes.com)

4. W. Guijuan, W. Zuoxun, Z. Yingchun and S. Lanyun, "A New Intelligent Control Terminal of Solar Street

Light," International Conference on Intelligent Computation Technology and Automation (ICICTA), 2011, pp.

321-324.

5. “Art of Electronics, 3rd Edition, errata”. Horowitz, Paul. April 7, 2015

6. Diode up to Double Pole Switch reference – openelectrical.org and en.wikipedia.org which is copyrighted under

GND license.

a) Physical Explanation – General Semiconductors. Link: https://www.element14.com/community/docs/DOC-

22519/l/physical-explanation--general-semiconductors

b) Rectifiers: Application Note, VISHAY GENERAL SEMICONDUCTOR.

c) The American heritage science dictionary. Houghton Mifflin Company. 2005.

d) Voltage Regulator - www.circuitstoday.com

e) Transformer - http://www.electrical4u.com/

f) Resistors, Capacitors and Relay - Bird, John (2010). Electrical and Electronic Principles and Technology.

Rutledge. pp. 63–76, Mason, C. R. "Art & Science of Protective Relaying, Chapter 2, GE Consumer &

Electrical Y Wu (2004). "Theory of resistor networks: The two-point resistance". Journal of Physics A:

Mathematical and General 37

g) LDR (Light Dependent Resistor)–Fig.4, 5, 6(a) and 6(b) respectively under the mentioned sections’ reference -

http://www.electrical4u.com, Fig. 7 reference – en.wikipedia.org under Article name – Photo resistor,

Contributor – NevitDilmen.

h) Construction of Photocell – same as the references of NPN Transistor.

i) Robert S. Mroczkowski, Electrical Connector Handbook Theory and Applications, McGraw Hill, 1998 ISBN 0-

07-041401-7, chapter 1

j) "Switch". The Free Dictionary. Farlex. 2008, "Switch". The American Heritage Dictionary, College Edition.

Houghton Mifflin. 1979. p. 1301,Terminology on "Light wiring" differing US and UK usage of the term

'WAYS' when referring to switches

k) Re-considering the economics of photovoltaic power. UN-Energy (Report) (United Nations).

l) Battery Reference Book (third ed.). Crompton, T. R. (2000-03-20). Newnes. p. Glossary 3. ISBN 0080499953