MINIREPORT.docx

AUTOMATIC ROOM LIGHT CONTROLLER WITH VISITOR COUNTER

MINI PROJECTSubmitted in partial fulfillment of therequirement for the award of the Degree of

BACHELOR OF TECHNOLOGYinAPPLIED ELECTRONICS AND INSTRUMENTATION ENGINEERINGofMAHATMA GANDHI UNIVERSITY, KOTTAYAM

ByAMALJYOTHI ABRAHAMReg. No.10009874

MAR BASELIOS CHRISTIAN COLLEGE OF ENGINEERING AND TECHNOLOGYPEERMADE-685531APRIL 2013

MAR BASELIOS CHRISTIAN COLLEGE OFENGINEERING AND TECHNOLOGY PEERMADE

CERTIFICATE

This is to certify that B.tech mini project entitled AUTOMATIC ROOM LIGHT CONTROLLER WITH VISITOR COUNTER submitted by AMALJYOTHI ABRAHAM(Reg. No:10009874), Dept. of Applied Electronics and Instrumentation , Mar Baselios Christian College of Engineering and Technology, Peermade for the purpose of mini project evaluation, is a record of bonafide work carried out by him under my supervision, in partial fulfilment for the award of the degree of Bachelor of Technology in Applied Electronics and Instrumentation Engineering of Mahatma Gandhi University, Kottayam, as per the academic and research ethics.

Place:PeermadeDate:

Internal GuideProject CoordinatorHead of Department

External Examiner Internal Examiner

ABSTRACT

The Project, Automatic Room Light Controller with Visitor Counter using Microcontroller is a reliable circuit that takes over the task of controlling the room lights as well us counting number of persons/ visitors in the room very accurately. When somebody enters into the room then the counter is incremented by one and the light in the room will be switched ON and when any one leaves the room then the counter is decremented by one. The light will be only switched OFF until all the persons in the room go out. The total number of persons inside the room is also displayed on the LCD displays. The microcontroller does the above job. It receives the signals from the sensors, and this signal is operated under the control of software which is stored in ROM. Microcontroller AT89C51 continuously monitor the Infrared Receivers, When any object pass through the IR Receiver's then the IR Rays falling on the receiver's are obstructed , this obstruction is sensed by the Microcontroller.Keywords: Controller; Counter; Visitor; LCD; Sensor; ROM; IR; Obstruction;

ACKNOWLEDGEMENTWe would like to use this opportunity to express our gratitude to the person who provided all facilities to complete the mini project.We wish to express our sincere gratitude to Dr. PAUL K MATHEW, PRINCIPAL OF MBCCET, Mr. JISSMOHAN K, HOD of AEI department, for the encouragement and valuable suggestions.We would like to take this opportunity to thank Mrs.Merin Pius and Mrs. C Narmatha, our staff in charge for their constant help and encouragement, without whose help this project would have remained a distant dream. We are also greatful to Mr.Mobin M and Mr Devajen A, staff of AEI department for giving necessary guidance for completing this project. I also express gratitude to our parents, batch mates and department staff for their support in their venture.Last but not the least, we thank the almighty GOD, for his blessings without which this project would not have been possible.

Name :Amaljyothi AbrahamReg.No :10009883

TABLE OF CONTENTSChapter No.TitlePage No.LIST OF FIGURESviiLIST OF TABLESviiiLIST OF ABBREVIATIONSixCHAPTER 1 INTRODUCTION11.1Objective11.2Aim1 1.3Overview1CHAPTER 2 PRELIMINARY DESIGN32.1Basic Block Diagram3 2.2Description3CHAPTER 3DESIGNED CIRCUIT43.1Circuit Diagram4 3.2Circuit Working5CHAPTER 4COMPONENTS USED64.1Components List6 4.2Components Description74.2.1AT89C51-Microcontroller74.2.2ULN2003-Relay driving IC8 4.2.3 LM 7805 Voltage Regulator IC94.2.4Transistor94.2.5IR Transmitter And Receiver104.2.6LCD Display104.2.7Resistors114.2.8Capacitors114.2.9LEDs114.2.10Diodes124.4.11Relay124.2.12Crystal Oscillator13CHAPTER 5PCB LAYOUT14CHAPTER 6COMPONENTS LAYOUT15CHAPTER 7PCB DESIGN AND FABRICATION 167.1Printed Circuit Board16 7.2History16 7.3Manufacturing177.3.1Materials177.3.2Patterning (Etching)187.3.3Chemical Etching187.3.4Lamination197.3.5Drilling197.3.6Solder Resist207.3.7Screen Printing20 7.4Test217.4.1Printed Circuit Assembly217.4.2Protection And Packaging23CHAPTER 8SOLDERING24 8.1Process24 8.2Soldering And Brazing25 8.3Silver Soldering26CHAPTER 9ADVANTAGES AND DISADVANTAGES27CHAPTER 10APPLICATIONS 28CHAPTER 11CONCLUSION29CHAPTER 12FUTURE DEVELOPMENTS30REFERENCES31APPENDIX

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LIST OF FIGURESFigure No.Figure Name Page No. Figure 2.1.1Block Diagram3 Figure 3.1.1Circuit Diagram4 Figure 4.2.1.1Pinout Diagram7 Figure 4.2.2.1Logic Diagram8 Figure 4.2.2.2Schematic Diagram9 Figure 5.1PCB Layout14 Figure 6.1Components Layout15 Figure 7.4.1.1Sample PCB Assembly21

LIST OF TABLESTable No.Title Page No.4.1Components List6

LIST OF ABBREVIATIONSIRInfra RedROMRead Only MemoryLCDLiquid Crystal DisplayLEDLight Emitting DiodeICIntegrated Circuit

CHAPTER 1INTRODUCTIONElectricity is one the most important resources in a country. We should conserve electricity. But many times we come outside the room or hall and forget to turn off the lights, thus electricity is wasted. To overcome this we are going to implement a project called Automatic room light controller with visitor counter.1.1 OBJECTIVE:The objective of this project is to make a controller based model to count number of persons visiting particular room and accordingly light up the room. Here we can use sensor and can know present number of persons.Also if at all one wants to know the number of people present in room so as not to have congestion, this circuit proves to be helpful.1.2 AIMIn this competitive world and busy schedule human cannot spare time to perform his daily activities manually. The most common thing that he forgets to do is switching OFF the lights wherever they are not required. This project is a standalone automatic room light with visitor counter. The main aim of the project is to control the lights in a room depending upon lighting that is present in the room and count the number of persons entering into the room. Use of embedded technology makes this closed loop feedback control system efficient and reliable. 1.3 OVERVIEWThis Project Automatic Room Light Controller with Visitor Counter using Microcontroller is a reliable circuit that takes over the task of controlling the room lights as well us counting number of persons/ visitors in the room very accurately. When somebody enters into the room then the counter is incremented by one and the light in the room will be switched ON and when any one leaves the room then the counter is decremented by one. The light will be only switched OFF until all the persons in the room go out. The total number of persons inside the room is also displayed on the seven segment displays.The microcontroller does the above job. It receives the signals from the sensors, and this signal is operated under the control of software which is stored in ROM. Microcontroller AT89C51 continuously monitor the Infrared Receivers, When any object pass through the IR Receiver's then the IR Rays falling on the receiver are obstructed , this obstruction is sensed by the Microcontroller.

CHAPTER 2PRILIMINARY DESIGN2.1 BASIC BLOCK DAGRAMTransmitter 1Transmitter2Receiver 1Receiver 2Light Relay LCDMicro-controller

Figure 2.1.1: Block diagram2.2 DESCRIPTIONAs shown in the block diagram, the persons entering or leaving are sensed by the sensors used. The sensing part consists of twoIRtransmitter and receiver.The output of the receiver is given to the microcontroller. One pair of transmitter is placed first and other as next. According to the order with which the IR is cut, the microcontroller observes whether the person has entered the room or left. The microcontroller is programmed to control the light according to the sensor output. The number of persons inside the room and total count is displayed on the LCD display. The microcontroller does the counting. It also controls the light the room through a relay connection. A relay is one which is used to switch the ac supply using a small dc supply. Thus the room light is controlled automatically.

CHAPTER 3DESIGNED CIRCUIT3.1 CIRCUIT DIAGRAM

Figure 3.1.1: Circuit diagram3.2CIRCUIT WORKINGThe persons entering the room are sensed by the IR sensors used. The output of the receiver is usually high. When an obstruction occurs it becomes low. It is analysed by the microcontroller via a transistor network. According to the order which the IR sensors are the microcontroller turns ON/OFF the light. If a person is entering the room the microcontroller senses it from the receiver and turns ON the light by a relay network and increments the count. It is displayed on the LCD display. The light remains tuned ON until the last person leaves. The microcontroller also counts the total number of visitors entered the room and displays it on the LCD display. In the relay network, a relay driving IC ULN2003 is used. The relay is used to switch the ac power. The relay is connected in normally open condition. Whenever the pin of the microcontroller to the relay becomes high the switch is thrown to normally closed condition. Thus the light is controlled. For the whole circuit we are using a 5V dc supply. It is obtained by using a 7805 regulator IC. The ac given is first rectified and filtered. Thus a room light can be controlled.The microcontroller is the core element in the circuit. It is programmed so as to count, display the number of persons entered and to switch the light accordingly. If a person enters the room, the microcontroller increments its count, also the final count. It turns ON the light by giving a signal to the relay driving IC and thereby controlling the relay to switch. The relay is normally connected as normally open switch. When the relay driving IC gives a signal, the relay switches to the normally closed position.When the light is to be turned OFF, the microcontroller gives the input to the relay via the relay driving IC. During this, the relay switches from the normally closed condition to the normally open condition. The number of persons inside is displayed on the LCD display, also it is displays the total number of persons visited the room. The microcontroller is connected directly to the LCD display to display the counts.

CHAPTER 4COMPONENTS USED4.1 COMPONENTS LISTTable 4.1: Components List4.2 COMPONENTS DESCRIPTIONSl No.COMPONENTSPECIFICATIONQUANTITY

1DIODE1N 40043

2CAPACITORS0.33 F 4

47 F 1

470 F1

3Quad NAND GateIC CD 40111

4UP/DOWN DECADE COUNTERIC 741921

5BCD to SEVEN SEGMENT DRIVERIC CD45111

6SEVEN SEGMENT DISPLYLT 543 1

7IR RECEIVERTSOP 1738 1

8LM 7805IC 1

9FLIP FLOPIC 7473 2

10H BRIDGE MOTOR DRIVER ICL293D 1

11DC MOTOR8V 1

12SPDT FOOT SWITCH- 2

13TRANSFORMER9-0-9 1

14RESISTORS10K 4

330 6

22K 1

1K 1

4.2.3LM7805- REGULATOR ICThe LM7805 is a three terminal positive regulator is available in theTO-220/D-PAK package and with several fixed output voltages, making them useful in a wide range of applications. Each type employs internal current limiting, thermal shut down and safe operating area protection, making it essentially indestructible. If adequate heat sinking is provided, they can deliver over 1A output current. Although designed primarily as fixed voltage regulators, these devices can be used with external components to obtain adjustable voltages and currents.

4.2.5IR TRANSMITTER AND RECEIVERInfrared radiation is the portion of electromagnetic spectrum having wavelengths longer than visible light wavelengths, but smaller than microwaves, i.e., the regionroughly from 0.75m to1000 m is the infrared region. Infrared waves are invisible to human eyes. The wavelength region of 0.75m to 3 m is called near infrared, the region from 3 m to 6 m is called mid infrared and the region higher than 6 m is called far infrared. (The demarcations are not rigid; regions are defined differently by many).Aninfraredsensor is an electronic device that emits and/or detectsinfrared radiationin order to sense some aspect of its surroundings. Infrared sensors can measure the heat of an object, as well as detect motion. Many of these types of sensors only measure infrared radiation, rather than emitting it, and thus are known as passive infrared (PIR) sensors.All objects emit some form of thermal radiation, usually in the infrared spectrum. This radiation is invisible to our eyes, but can be detected by an infrared sensor that accepts and interprets it. In a typical infrared sensor like amotion detector, radiation enters the front and reaches the sensor itself at the center of the device. This part may be composed of more than one individual sensor, each of them being made from pyroelectric materials, whether natural or artificial. These are materials that generate an electrical voltage when heated or cooled.4.2.6 SEVEN SEGMENT DISPLAY An LED or Light Emitting Diode, is a solid state optical PN-junction diode which emits light energy in the form of photons when it is forward biased by a voltage allowing current to flow across its junction, and in Electronics we call this process electroluminescence. The actual colour of the visible light emitted by an LED, ranging from blue to red to orange, is decided by the spectral wavelength of the emitted light which itself is dependent upon the mixture of the various impurities added to the semiconductor materials used to produce it. Light Emitting Diodes have many advantages over traditional bulbs and lamps, with the main ones being their small size, long life, various colours, cheapness and are readily available, as well as being easy to interface with various other electronic components and digital circuits.But the main advantage of light emitting diodes is that because of their small die size, several of them can be connected together within one small and compact package producing what is generally called a 7-segment Display. The 7-segment display, also written as seven segment display, consists of seven LEDs (hence its name) arranged in a rectangular fashion as shown. Each of the seven LEDs is called a segment because when illuminated the segment forms part of a numerical digit (both Decimal and Hex) to be displayed. An additional 8th LED is sometimes used within the same package thus allowing the indication of a decimal point, (DP) when two or more 7-segment displays are connected together to display numbers greater than ten. Each one of the seven LEDs in the display is given a positional segment with one of its connection pins being brought straight out of the rectangular plastic package. These individually LED pins are labelled from a through to g representing each individual LED. The other LED pins are connected together and wired to form a common pin. So by forward biasing the appropriate pins of the LED segments in a particular order, some segments will be light and others will be dark allowing the desired character pattern of the number to be generated on the display. This then allows us to display each of the ten decimal digits 0 through to 9 on the same 7-segment display. The displays common pin is generally used to identify which type of 7-segment display it is. As each LED has two connecting pins, one called the Anode and the other called the Cathode, there are therefore two types of LED 7-segment display called: Common Cathode (CC) and Common Anode (CA). The difference between the two displays, as their name suggests, is that the common cathode has all the cathodes of the 7-segments connected directly together and the common anode has all the anodes of the 7-segments connected together and is illuminated as follows.

1. The Common Cathode (CC) In the common cathode display, all the cathode connections of the LED segments are joined together to logic 0 or ground. The individual segments are illuminated by application of a HIGH, or logic 1 signal via a current limiting resistor to forward bias the individual Anode terminals (a-g). Common cathode display 2 .The Common Anode (CA) In the common anode display, all the anode connections of the LED segments are joined together to logic 1. The individual segments are illuminated by applying a ground, logic 0 or LOW signal via a suitable current limiting resistor to the Cathode of the particular segment (a-g). Common anode displayIn general, common anode displays are more popular as many logic circuits can sink more current than they can source. Also note that a common cathode display is not a direct replacement in a circuit for a common anode display and vice versa, as it is the same as connecting the LEDs in reverse, and hence light emission will not take place.Depending upon the decimal digit to be displayed, the particular set of LEDs is forward biased. For instance, to display the numerical digit 0, we will need to light up six of the LED segments corresponding to a, b, c, d, e and f. Then the various digits from 0 through 9 can be displayed using a 7-segment display as shown..4.2.7 RESISTORSA resistor is a two-terminalelectronic component that produces a voltage across its terminals that is proportional to the electric current passing through it in accordance with Ohm's law: V = IR.Resistors are elements of electrical networks and electronic circuits and are ubiquitous in most electronic equipment. Practical resistors can be made of various compounds and films, as well as resistance wire (wire made of a high-resistivity alloy, such as nickel/chrome).4.2.8CAPACITORSA capacitor or condenser is a passive electronic component consisting of a pair of conductors separated by a dielectric (insulator). When a potential difference (voltage) exists across the conductors, an electric field is present in the dielectric. This field stores energy and produces a mechanical force between the conductors. The effect is greatest when there is a narrow separation between large areas of conductor; hence capacitor conductors are often called plates. Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass, in filter networks, for smoothing the output of power supplies, in the resonant circuits that tune radios to particular frequencies and for many other purposes.4.2.9 LEDSAlight-emittingdiode(LED) is asemiconductorlight source.LEDs are used as indicator lamps in many devices and are increasingly used for other lighting. Appearing as practical electronic components in 1962,early LEDs emitted low-intensity red light, but modern versions are available across thevisible,ultraviolet, andinfraredwavelengths, with very high brightness.When a light-emitting diode is switched on,electronsare able to recombine with holes within the device, releasing energy in the form ofphotons. This effect is calledelectroluminescenceand the colour 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 1mm2), and integrated optical components may be used to shape itsradiation pattern.LEDs present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. However, LEDs powerful enough for room lighting are relatively expensive and require more precise current and heat management than compactfluorescent lampsources of comparable output.4.2.10 DIODEAdiodeis a two-terminalelectronic componentwith an asymmetrictransfer characteristic, with low (ideally zero)resistanceto current flow in one direction, and high (ideallyinfinite) resistance in the other. Asemiconductor diode, the most common type today, is acrystallinepiece ofsemiconductormaterial with apn junctionconnected to two electrical terminals.Avacuum tube diodeis avacuum tubewith twoelectrodes, aplate(anode) and heated cathode.The most common function of a diode is to allow an electric current to pass in one direction (called the diode'sforwarddirection), while blocking current in the opposite direction (thereversedirection). Thus, the diode can be viewed as an electronic version of acheck valve. This unidirectional behaviour is calledrectification, and is used to convertalternating currenttodirect current, including extraction ofmodulationfrom radio signals in radio receiversthese diodes are forms ofrectifiers.

CHAPTER 5PCB LAYOUT

Figure 5.1: PCB Layout

CHAPTER 6COMPONENTS LAYOUT

Figure 6.1 : Components Layout

CHAPTER 7PCB DESIGN AND FABRICATION7.1 PRINTED CIRCUIT BOARDA printed circuit board, or PCB, is used to mechanically support and electrically connect electronics components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a nonconductive substrate. It is also referred to as printed wiring board (PWB) for etched wiring board. A PCB populated with electronics components is a printed circuit assembly (PCA), also known as printed circuit board assembly or PCB assembly (PCBA) printed circuit boards are used in virtually all but the simplest commercially produced electronics devices.Alternatives to PCBs include wire wrap and point-to-point construction. PCBs are often less expensive and more reliable than these alternatives, though they require more layout effort and higher initial cost. PCBs are much cheaper and faster for high- volume production since production and soldering of PCBs can be done by automated equipment. Much of the electronics industries PCB design, assembly, and quality control needs are set by standards that are published by the IPC organisation.7.2 HISTORYDevelopment of the methods used in modern PCB started early in the 20th century. In 1903, a German inventor, Albert Hanson, described flat foil conductors laminated to an insulating board, in multiple layers. Thomas Edison experimented with chemical methods of plating conductors onto linen paper in 1904. Arthur Berry in 1913 patented a print-and-etch method in Britain, and in the United States Max Scoop obtained a patent to flame-spray metal onto a board through a patterned mask. Charles Durcase in 1927 patented a method of electroplating circuit patterns. The Austrian Jewish engineer Paul Eisler invented printed circuit while working in England around 1936 as part of a radio set. Around 1943 the USA began to use the technology on a large scale to make proximity fuses for use in World War II. After the war, in 1948, the USA released the invention for commercial use. Printed circuits did not become commonplace in consumer electronics until the mid-1950s, after the auto-Sembly process was developed by the United States Army. Before printed circuits (and for a while after their invention), point-to-point construction was used. For prototypes, or small production runs, wire wrap or turret board can be more efficient. Predating the printed circuits invention, and similar in spirit, was John Sargroves 1936-1947 Electronics Circuit Making Equipment (ECME) which sprayed metal onto a Bakelite plastic board. The ECME could produce 3 radios per minute. During World War II, the development of the anti-aircraft proximity fuse required an electronics circuit that could withstand being fired from a gun, and could be produced in quantity. The Centra Lab division of globe union submitted a proposal which make the requirements: a ceramic plate would be screen printed with metallic pain for conductors and carbon metal for resistors, with ceramic disc capacitors and sub miniature vacuum tubes soldered in place. Originally, every electronics component had wire leads, and the PCB had holes drilled for each wire of each component. The components lead were the passed through the holes and soldered to the PCB trace. This method of assembly is called through-hole construction. In 1949, Moe Abramson and Stanislaus F. Danko of the United States Army Signal Corps developed the auto-sembly process in which the component leads were inserted into a copper foil interconnection pattern and dip soldered. The patent they obtained in 1956 was assigned to the U. S. Army with the development of board lamination and etching techniques, this concept evolved into the standard PCB fabrication process in use today. Soldering could be done automatically by passing the board over a ripple, or wave, of molten solder in a wave-soldering machine. However, the wires and holes are wasteful since drilling hole is expensive and the protruding wires are merely cut off. In recent years, the use of surface mount parts has gained popularity as the demand for smaller electronics packaging and greater functionality has grown. 7.3 MANUFACTURING7.3.1 MATERIALSConducting layers are typically made of thin copper foil. Insulating layers dielectric is typically laminated together with epoxy resin prepreg. The board is typically coated with a solder mask that is green in colour. Other colours that are normally available are blue, black, white and red. These are quite a few different dielectrics that can be chosen to provide different insulating valves depending on the requirements of the circuit. Some of these dielectrics are polytetrafluoroethylene (Teflon), FR-4, FR-1, CM-1 or CM-3. Well known prepreg materials used in the PCB industry are FR-2 (phenolic cotton paper), FR-3(cotton paper and epoxy), and FR-4 (woven glass and epoxy), FR-5 (woven glass and epoxy), FR-6 (matte glass and polyester), G-10 (woven glass and epoxy), CM-1 (cotton paper and epoxy), CEM-2 (cotton paper and epoxy), CEM-3 (non-woven glass and epoxy), CEM-4 (woven glass and epoxy), CEM-5 (woven glass and polyester). Thermal expansion is an important consideration especially with bold grid array (BGA) and naked die technologies, and glass fibre offers the best dimensional stability.FR-4 is by far the most common material used today. The board with copper on it is called copper-clad laminate. Copper foil thickness can be specified in ounces per square foot or micrometres. On ounce per square foot is 1.344 miles or 34 micrometres. 7.3.2 PATTERNING (ETCHING)The vast majority of PCBs are made bonding a layer of copper over the entire substrate, sometimes on both sides, (creating a blank PCB) then removing unwanted copper after applying temporary mask. (e. g., by etching), leaving only the desired copper traces. A few PCBs are made by adding traces to the bare substrate (or a substrate with a very thin layer of copper) usually by a complex process of multiple electroplating steps. The PCB manufacturing method preliminarily depends on whether it is for production volume or sample or prototype quantities. Double-sided boards or multi-layer boards use plated- through holes, called vias, to connect traces on either side of the substrate.7.3.3 CHEMICAL ETCHINGChemical etching is done with ferric chloride, ammonium persulfate, or sometimes HCl. For PTH (plated through holes), additional steps for electroless deposition are done after the hole are drilled, then copper is electroplated to build up the thickness, the boards are screened, and plated with tin/lead. The tin/lead becomes the resist leaving the bare, copper to be etched away. The simplest method, used for small-scale production and often by hobbyist, is immersion etching, in which the board is submerged in etching solution such as ferric chloride. Compared with methods used for mass production, the etching time is long. Heat and agitation can be applied to the bath to speed the etching rate. In bubble etching, air is passed through the etchant bath to agitate the solution and speed up etching. Splash etching uses a motor-driven paddle to splash boards with etchant; the process has become commercially obsolete since it is not as fast as spray etching. In spray etching, the etchant solution is distributed over the board by nozzles, and recalculated by pumps. Adjustment of the nozzle pattern, flow rate, temperature, and etchant composition gives predictable control of etching rates and high production rates.As more copper is consumed from the boards, the etchant becomes saturated and less effective; different etchants have different capacities for copper, with some as high as 150gms of copper per litre of solution. In commercial use, etchants can be regenerated to restore their activity, and the dissolved copper recovered and sold. Small-scale etching requires attention to disposal of used etchant, which is corrosive and toxic due to its metal content. The etchant removes copper on all surfaces exposed by the resist. Undercut occurs when etchant attacks the thin edge of copper under the resist; this can reduce conductor widths and cause open- circuits. Careful control of etch time is require to prevent undercut. Where metallic plating is used as a resist, it can Overhang which can cause short- circuits between adjacent traces when closely spaced. Overhang can be removed by wire-brushing the board after etching. 7.3.4 LAMINATIONSome PCBs have trace layers inside the PCB and are called multi-layer PCBs. These are formed by bonding together separately etched thin boards. 7.3.5 DRILLINGHoles through a PCB are typically drilled with small-diameter drill bits made of solid coated tungsten carbide. Coated tungsten carbide is recommended since many board materials are very abrasive and drilling must be high RPM and high feed to be cost effective. Drill bits must be remain sharp so as not to mar or tear the traces. Drilling with high-speed-steel is simply not feasible since the drill bits will duty quickly and thus tears the copper and ruin the boards. The drill is performed by automated drilling machines with placement controlled by a drill tape or drill file. These computer-generated files are also called numerically controlled drill (NCD)files or Excellon files. The drill file describes the location and siz of each drill hole. These holes are often filled with annular rings (hollow rivets) to create vias. Vias allow the electrical and thermal connection of conductors of conductors on opposite sides of the PCB. When a very small vias are required, drilling with mechanical bits is costly because high rates of wear and breakage. In this case, the vias may be evaporated by lasers. Laser-drilled vias typically have an inferior surface finish inside the hole. These holes are called microvias. It is also possible with controlled-depth drilling, laser drilling, or by pre-drilling the individual sheets of the PCB before lamination, to produce holes that connect only some of the copper layers, rather than passing through the entire board. These holes are called blind vias when they connect an internal copper layer to an outer layer, or buried vias when they connect two or more internal copper layers and no outer layers.The walls of the holes, for boards with two or more layers, are made conductive then plated with copper to form plated-through holes that electrically connect the conducting layers of the PCB. For multilayer boards, those with four layers or more, drilling typically produces a smear of the high temperature decomposition products of bonding agent in the laminate system. Before the holes can be plated through, this smear must be removed by a chemical de-smear process, or by plasma-etch. Removing (etching back) the smear also reveals the interior conductor as well. 7.3.6 SOLDER RESISTAreas that should not be soldered may be covered with a polymer solder resist (Solder mask) coating. The solder resist prevents solder from bringing between conductors and creating short circuits. Solder resist also provides some protection from the environment. Solder resist is typically 20-30 micrometres thick.7.3.7 SCREEN PRINTINGLine art and text may be printed onto the outer surfaces of a PCB by screen printing. When space permits, the screen print text can indicate component designators, switch setting requirements, test points, and other features helpful in assembling, testing, and servicing the circuit board. Screen print is also known as the silk screen, or, in one sided PCBs, the red print. Lately some digital printing solutions have been developed to substitute the traditional screen printing process. This technology allows printing variable data onto the PCB including serialization and barcode information for the traceability purposes.7.4 TEST Unpopulated boards may be subjected to a bare-board test where each circuit connection (as defined in a net list) is verified as correct on the finished bread board. For high volume production, a bed of nails tester, a fixture or a rigid needle adapter is used to make contact with copper lands or holes on one or both side of the board to facilitate testing. A computer will instruct the electrical test unit to apply a small voltage to each contact point on the bed-of-nails as required, and verify that such voltage appears at other appropriate contact points. A short on a board would be a connection where there should not be one; an open is between two points that should be connected but are not. For small- or medium-volume boards, flying robe and flying-grid testers use moving test heads to make contact with the copper/silver/gold/solder lands or holes to verify the electrical connectivity of the board under test. Another method for testing is industrial CT scanning, which can generate a 3D rendering of the board along with 2D image slices and can show details such a soldered paths and connections.7.4.1 PRINTED CIRCUIT ASSEMBLY

Figure 7.4.1.1: Sample PCB assemblyAfter the PCB is completed, electronics components must be attached to form a functional printed circuit assembly, or PCA (sometimes called a printed circuit board assembly PCBA). In through-hole construction, component leads are inserted in holes. In surface-mount construction, the components are placed on pads or lands on the outer surfaces of the PCB. In both kinds of construction, component leads are electrically and mechanically fixed to the board with a molten metal solder.There are a variety of soldering techniques used to attach component to PCB. High volume production is usually done with SMT placement machine and bulk wave soldering or reflow ovens, but skilled technicians are able to solder very tiny parts (for instance 0201 packages which are 0.02 in. by 0.01 in.) by hand under a microscope, using tweezers and a fine tip soldering iron for small volume prototypes. Some parts may be extremely difficult to solder by hand, such as BGA packages. Often, through-hole and surface-mount construction must be combined in a single assembly because some required components are available only in surface-mount packages, while others are available only through-hole packages. Another reason to use both methods is that through-hole mounting can provide needed strength for components likely to endure physical stress, while components that are expected to go untouched will take up less space using surface-mount techniques.After the board has been populated it may be tested in a variety of ways. While the power is off, visual inspection, automated optical inspection. JEDEC guidelines for PCB component placement, soldering, and inspection are commonly used to maintain quality control in this stage of PCB manufacturing. While the power is off, analog signature analysis, power-off testing While the power is on, in-circuit test, where physical measurements (i.e. voltage, frequency) can be done. While the power is on, functional test, just checking if the PCB does what it had been designed to do.To facilitate these tests, PCBs may be designed with extra pads to make temporary connections. Sometimes these pads must be isolated with resistors. The in-circuit test may also exercise boundary scan test features of some components. In-circuit test systems may also be used to program non-volatile memory components on the board.In boundary scan testing, test circuits integrated into various ICs on the board from temporary connections between the PCB traces to test that the ICs are mounted correctly. Boundary scan testing requires that all the ICs to be tested use a standard test configuration procedure, the most common one being the Joint Test Action Group (JTAG) standard. JTAG test architecture provides a means to test interconnects between integrated circuits on a board without using physical test probes. JTAG tool vendors provide various types of stimulus and sophisticated algorithms, not only to detect the failing nets, but also to accelerate the faults to specific nets, devices and pins.When boards failed test, technicians may desolder and replace filled components, a task known as rework.7.4.2 PROTECTION AND PACKAGING PCBs intended for extreme environments often have a conformal coating, which is applied by dipping or spraying after the components have been soldered. The coat prevents corrosion and leakage currents or shorting due to condensation. The earliest conformal coats were wax; modern conformal coats are usually dips of dilute solutions of silicone rubber, polyurethane; acrylic, or epoxy. Another technique for applying a conformal coating is for plastic to be sputtered on to the PCB in a vacuum chamber. the chief disadvantage of conformal coatings is that servicing of the board is rendered extremely difficult.Many assembled PCBS are static sensitive, and therefore must be placed in antistatic bags during transport. When handling these boards, the user must be grounded (earthed.) improper handling techniques might transmit an accumulated static charge through the board, damaging or destroying components. Even bare boards are sometimes static sensitive. Traces have become so fine that its quite possible to blow an etch off the board (or change its characteristics) with a static charge. This is especially true on non-traditional PCBs such as MCMs and microwave PCB.

CHAPTER 8SOLDERINGSoldering is a process in which two or more metal items are joined together by melting and flowing a filter metal (solder) into the joint, the filet metal having a lower melting point than the work piece. Soldering differs from welding in that soldering does not involve melting the work pieces. In bracing the filter metal melts at a higher temperature, but the work piece metal does not melt. Formerly nearly all solders contained lead, but environmental concerns have increasingly dictated use of lead-free alloys for electronics purposes.8.1 PROCESSESThere are three forms of soldering, each requiring progressively higher temperatures and producing an increasingly stronger joint strength:1. Soft soldering, which originally used a tin-lead alloy as the filler metal2. Silver soldering, which uses an alloy containing silver.3. Bracing which uses a brass alloy for filler.The alloy of the filler metal for each type of soldering can be adjusted to modify the melting temperature of the filler. Soldering differs from gluing significantly in that the filler metals alloy with the work piece at the junction to for a gas- and liquid-tight bond.Soft soldering is characterised by having a melting point of the filler metal below approximately 400 C (752 F), whereas silver soldering and brazing use higher temperatures, typically requiring a flame or carbon arc torch to achieve the melting of the filler. Soft solder filler metals are typically alloys (often containing lead) that have liquidus temperature below 350 C.In this soldering process, heat is applied to the parts to be joined, causing the solder melt and bond to the work pieces in an alloying process called wetting. In stranded wire, the solder is drawn up into the wire by capillary action in a process called wicking. Capillary action also takes place when the work pieces are very close together or touching. The joint strength is dependent on the filler metal used. Soldering produces electrically-conductive, water and gas-tight joints.Each type of solder offers advantages and disadvantages. Soft solder is so called because of the soft lead that is its primary ingredient. Soft soldering uses the lowest temperatures but does not make a strong join and is unsuitable for mechanical load-bearing applications. It is also unsuitable for high- temperature applications as it softens and melts. Silver soldering, as used by jewellers, machinists and in some plumbing applications, requires the use of a torch or other high-temperature source, and is much stronger that soft soldering. Brazing provides the strongest joint but also requires the hottest temperatures to melt the filler metal, requiring a torch or other high temperature source and darkened goggles to protect the eyes from the bright light produced by the white-hot work. It is often used to repair cast-iron objects furniture, etc.Soldering operations can be performed with hand tools, one joint at a time, or enmasse on a production line. Hand soldering is typically performed with a soldering iron, soldering gun, or a torch, or occasionally a hot-air pencil. Sheet metal was traditionally done with soldering coppers directly heated by a flame, with sufficient stored heat in the mass of the soldering copper to complete a joint; torches or electrically-heated soldering irons are more convenient. All soldered joints require the same elements of cleaning of metal parts to be joined, fitting up the joint, heating the parts, applying flux, applying the filler, removing heat and holding the assembly still until the filler metal has completely solidified. Depending on the nature of flux material used, cleaning of joints may be required after they have cooled.Each alloy has characteristics that work best for certain applications, notably strength and conductivity, and each type of solder and alloy has different melting temperatures. The term silver solder likewise denotes the type of solder that is used. Some soft solders are silver bearing alloys used to solder silver-plated items. Lead based solders should not be used on precious metals because the lead dissolves the metal and configures it.8.2 SOLDERING AND BRACINGThe distinction between soldering and brazing is based on the melting temperature of the filler alloy. A temperature of 450 C is usually used as a practical delineating point between soldering and brazing. Soft soldering can be done with a heated iron whereas the other methods require a higher temperature torch or furnace to melt the filler metal. Different equipment is usually required since a soldering iron cannot achieve high enough temperature for hard soldering or brazing. Brazing filler metal is stronger than silver solder, which is stronger that lead-based soft solder. Brazing solder are formulated primarily for strength, silver solder is used by jewellers to protect the precious metal and by machinist and refrigeration technicians for its strength but lower melting temperature than brazing, and the primary benefit of soft solder os the low temperature used (to prevent heat damage to electronics components and insulation).Since the joint is produces using a metal with a lower melting temperature that the work piece, the joint will weaken as the ambient temperature approaches the melting point of the filler metal. For that reason, the higher temperature processes produce joints which are effective at higher temperatures. Brazed connections can be a strong or nearly as strong as the parts they connect, even at elevated temperatures. 8.3 SILVER SOLDERINGHard soldering or Silver soldering is used to join precious and semi-precious metals such as gold, silver, brass, and copper. The solder is usually referred to as easy, medium, or hard. This refers to its melting temperature, not the strength of the joint. Extra easy solder contains 56% silver and has a melting point of 1,145 F (618 C). Extra-hard solder has 80% silver and melts at 1,370 F (740 C). If multiple joints are needed, then the jeweller will start with hard or extra-hard solder and switch to lower temperature solders for later joints.Silver solder is absorbed by the surrounding metal, resulting in a joint that is actually stronger that the metal being joined. The metal being joined must be perfectly flush, as silver solder cannot normally be used as filler and any gaps will remain.Another difference between brazing and soldering is how the solder is applied. In brazing, one generally uses rods that are touched to the joint while being heated. With silver soldering, small pieces of solder wire are placed onto the metal prior to heating. A flux, often made of borax and water, is used to keep the metal and solder clean and to prevent the solder from moving before it melts.

CHAPTER 9ADVANTAGES AND DISADVANTAGES9.1ADVANTAGES Low cost Easy to use Over loading can be reduced Passengers are aware of seat availability No need of door operators Less stress for the travelers This help Prevent Footboard Accidents9.2DISADVANTAGES It cannot be used when two person cross the door simultaneously. IR control is limited to line of sight.

CHAPTER 10APPLICATIONS In public transport service To count the number of visitors Extended to home too

CHAPTER 11CONCLUSIONIn todays world, there is a continuous need for automatic appliances. With the increase in standard of living, there is a sense of urgency for developing circuits that would ease the complexity of life. The project has two modules. First module is Visitor Counter and the other is automatic room light controller. Main concept behind this is to measure and display the number of persons inside the any room like seminar hall, conference room. When number of persons inside the room is zero, power supply inside the room can be cut using a relay interface. This will help to save electricity.This circuit is mostly used in fully automated industries. This type of automated lighting system helps to save energy. The circuit modified with two relays can be used to open and close the doors automatically. This can also be extended to home applications too. We can control light intensity and temperature in a room using this circuit.

CHAPTER 12FUTURE DEVELOPMENTS By incopreting microcontroller we can mprove performence By modifying this circuit and using two relays we can achieve a task of opening and closing the door. The circuit can be modified by controlling the light by sensing the intensity of light in the room.

REFERENCES

[1] Ajay V Deshmukh, Microcontrollers [THEORY AND APPLICATIONS]. Tata McGraw Hill Education Private Limited, 2005.[2] Muhammad Ali Mazidi, Janice GillispieMazidi&Rolin D. McKinlay, The 8051 Microcontroller and Enbedded Systems. Dorling Kindersley (India) Pvt. Ltd.[3] http://www.8051.info[last visited: 06/04/2013][4] http://www.datasheets4u.com [last visited: 10/04/2013][5] http://www.electronicsforyou.com [last visited: 12/04/2013]

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