Completely revised project 2016
- 1. Automatic Street Light Control Using LDR Sensor A 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 by Amit Kumar Ashish kumar Singh Chandan Kumar Neeraj kumar Shubham Ghosh Under the guidance of Mrs Tanushree Kumar DEPARTMENT OF ELECTRICAL ENGINEERING MCKV Institute of Engineering 243, G.T. Road (North), LILUAH, HOWRAH DEPARTMENT OF ELECTRICAL ENGINEERINMCKV Institute of Engineering Affiliated to West Bengal University of Technology NOVEMBER,2015
- 2. P a g e | 1 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 undermy supervision. Signature of the head of the department Signature of the supervisor Prof. Chandrani Sadhukhan Mrs Tanushree Kumar HEAD OF THE DEPARTMENT SUPERVISOR Assistant Professor Electrical Engineering Electrical Engineering 243 , G.T . Road(N) , Liluah 243 , G.T.Road (N) , Liluah Howrah-711204 Howrah-711204
- 3. P a g e | 2 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
- 4. P a g e | 3 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.
- 5. P a g e | 4 TABLEOF CONTENTS CERTIFICATE 1 ACKNOWLEDGEMENT 2 ABSTRACT Error! Bookmark not defined. LIST OF FIGURES 5 LIST OF TABLES 6 CHAPTER-1 7. OBJECTIVE OF THE PROJECT 7 CHAPTER-2 8 INTRODUCTION 8 CHAPTER-3 10 LITERATURE REVIEW 10 CHAPTER-4 12 DESCRIPTON OF COMPONENT USED 12 4.1 DIODE 12 4.1.1 FORWARD BIASING CHARACTERISTIC OF DIODE 13 4.1.2 REVERSE BIASING CHARACTERISTIC OF DIODE 13 4.2 ZENER DIODE 14 4.2.1 ZENER DIODE CIRCUIT 15 4.2.2 CHARACTERISTICS OF A ZENER DIODE 16 4.2.3 APPLICATION OF ZENER DIODE 16 4.2.4 ZENER DIODE AS VOLTAGE REGULATOR 16 4.3 RESISTOR 17 4.4 CAPACITOR 18 4.4.1 TYPES OF CAPACITORS 18 4.5 TRANSISTOR 20 4.5.1 DEFINITION OF BJT 20 4.5.2 N-P-N BIPOLAR JUNCTION TRANSISTOR 21 4.5.3 P-N-P BIPOLAR JUNCTION TRANSISTOR 21 4.5.4 WORKING PRINCIPLE OF BJT 22 4.6 LIGHT DEPENDENT RESISTOR 22 4.6.1 WORKING PRINCIPLE OF LDR 23 4.6.2APPLICATIONS OF LDR 23 4.7 LED 24 4.7.1WORKING PRINCIPLE OF LED 24 4.8 POTENTIOMETER 25 4.9 DRY CELL 26 4.10 FUSE 27 5.1 CIRCUIT DIAGRAM 28 5.2 COMPONENT USED AND THEIR SPECIFICATION 29 5.3 WORKING OF THE CIRCUIT 30 CHAPTER- 6 37 SCOPE OF POWERING THE CUIRCUIT 37 CHAPTER-7 38 ADVANTAGES AND APPLICATION 38 CHAPTER-8 39
- 6. P a g e | 5 REFERENCE 39 LIST OF FIGURES Page no. Fig.1 Symbolof diode 12 Fig.2 Biasingof diode 13 Fig.3 Forward biasing of diode 13 Fig.4 Reversebiasing of diode 14 Fig.5 Connection of diodeas a zener diode 15 Fig.6 Symbolof zener diode 15 Fig.7 Characteristics of zener diode 15 Fig.8Zener diodeas voltage regulator 17 Fig.9 Typesof transistor 20 Fig.10 n-p-n transistor 21 Fig.11 p-n-p transistor 21 Fig.12 Symbol of LDR 23 Fig.13 Symbol of LED 24 Fig.14 Symbol of Potentiometer 25 Fig.15 Symbol of cell and battery 26 Fig.16 A typical fuseused in the circuit 27 Fig.17 Circuit diagram 28 Fig.18 Waveform across source 32 Fig.19 Waveform after rectification 33 Fig.20 Waveform across zener diode 34
- 7. P a g e | 6 Fig:-21Waveform acrossC2 35 Fig.22 Waveform acrossEmitter and Base 36 LIST OF TABLES Page no. Table 1.Differentcomponents with their specifications 29 and price
- 8. P a g e | 7 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. 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.
- 9. P a g e | 8 CHAPTER-2 INTRODUCTION Basically, 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 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
- 10. P a g e | 9 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 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.
- 11. P a g e | 10 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 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
- 12. P a g e | 11 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 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
- 13. P a g e | 12 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 DESCRIPTON OFCOMPONENT USED 4.1 DIODE In 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
- 14. P a g e | 13 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. Figure:-2. Biasing of diode 4.1.1FORWARD BIASINGCHARACTERISTIC OFDIODE When 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.
- 15. P a g e | 14 4.1.2REVERSE BIASINGCHARACTERISTICOFDIODE In 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. 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
- 16. P a g e | 15 of p - type and n - type). And when the applied voltage exceeds anspecific amount zener breakdown takes place. 4.2.1 ZENER DIODE CIRCUIT Zener 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. Forconvenience 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.
- 17. P a g e | 16 Figure:-7. Characteristics of Zener Diode. 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 becauseat this point the current is the current is very rapid. 4.2.3 APPLICATION OFZENER DIODE Overvoltage 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 sourcepower.
- 18. P a g e | 17 4.2.4 ZENER DIODE AS VOLTAGE REGULATOR The 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, 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 becausethe regulating element is parallel to the load. The Zener diode producea stable reference voltage across the load which fulfils the criteria of regulator. 4.3 RESISTOR A 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
- 19. P a g e | 18 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. 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 CAPACITOR Capacitor is a passive element that stores electric charge statistically and temporarily as an static electric field. It is composed oftwo 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 CAPACITORS There are mainly two types of capacitor-
- 20. P a g e | 19 A) CERAMIC CAPACITOR Construction 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. 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 properpolarity. 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
- 21. P a g e | 20 be subsequently observed. If the opposite polarity is applied to the capacitor, the oxide layer is destroyed. 4.5 TRANSISTOR 4.5.1 DEFINITION OF BJT A 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.
- 22. P a g e | 21 4.5.2N-P-N BIPOLAR JUNCTION TRANSISTOR As 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 TRANSISTOR Similarly 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.
- 23. P a g e | 22 4.5.4 WORKINGPRINCIPLE OFBJT Figure 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 oppositeto 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 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
- 24. P a g e | 23 indicate a LDR, one of the most commonly used symbol is shown in the figure below. The arrow indicates light falling on it. Figure:-12. Symbol of LDR 4.6.1WORKINGPRINCIPLE OFLDR A 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 bythe 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 conductionband. 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 conductionband. 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 LDR LDR’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.
- 25. P a g e | 24 4.7 LED A light-emitting diode (LED) is a two-lead semiconductor light source. It is a p–njunction 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 WORKINGPRINCIPLE OFLED 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 conductionband 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
- 26. P a g e | 25 diodes but in gallium arsenide phosphide (GaAsP) and gallium phosphide (GaP) semiconductors, the electrons dissipate energy by emitting photons. If the semiconductor is translucent, the junction becomes the sourceof light as it is emitted, thus becoming a light-emitting diode, but when the junction is reverse biased no light will be produced bythe LED and, on the contrary, the device may also be damaged. 4.8POTENTIOMETER A potentiometer, informally a pot, is a three-terminal resistor with a sliding or rotating contactthat 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 controlelectrical 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
- 27. P a g e | 26 4.9 DRYCELL A Dry cell is a type of electricity-producing chemical cell, commonly used 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 cathodein the form of a central rod. Theelectrolyte is ammonium chloride in the form of a paste next to the zinc anode. The remaining spacebetween the electrolyte and carboncathode is taken up by a second pasteconsisting 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
- 28. P a g e | 27 4.10 FUSE 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 conductorwhich 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
- 29. P a g e | 28 CHAPTER-5 5.1 CIRCUIT DIAGRAM Figure:-17. Circuit diagram
- 30. P a g e | 29 5.2COMPONENT USEDAND THEIR SPECIFICATION Table:-1 Different components and their specification and price Serial No. Components Specifications Price(Rs) 1. A Capacitor 2.2uF,250v, Nonelectrolytic 7 B 47uF,25v Electrolytic 1 C 22uF,25v Electrolytic 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 0.20 3 Variable Resistor 20k ohm 2 4 Diode(4pcs.) In4007 0.50*4= 2 5 ZenerDiode A010 0.50 6 LDR Roboindia 3 7 White LED 5 8 Transistor Bt3904 3 9 Breadboard 80 10 Wires 10 11 Plug 10
- 31. P a g e | 30 5.3 WORKINGOFTHE CIRCUIT This 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, becauseif 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. Forthis reason the rectifier capacitor sourcemust be 350 volts, otherwise it will explore when connecting the circuit.
- 32. P a g e | 31 Now that the rectifier and a small current voltage, we must lower the voltage to 10 volts DC. Forthis 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 baseof 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.
- 33. P a g e | 32 Fig:-18.Waveformacrosssource
- 34. P a g e | 33 Fig:-19.Waveformafterrectification
- 35. P a g e | 34 Fig:-20.Waveformacrosszenerdiode
- 36. P a g e | 35 Fig:-21.Waveform acrossc2
- 37. P a g e | 36 Fig:-22.Waveformacross Emitter and Base
- 38. P a g e | 37 CHAPTER-6 SCOPE OF POWERINGTHE CUIRCUIT 1.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.
- 39. P a g e | 38 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 occurdue to manual operation can be eliminated completely.The automatic street light controller unit fabrication is costeffective 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.
- 40. P a g e | 39 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 SensorNetworks” 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