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    AUTOMATIC ROOM LIGHT CONTROLLER WITH

    BIDIRECTIONAL VISITOR COUNTER

    A PROJECT REPORT

    Submi tted by

    SARATH M.R.

    SARATH PRADEEP

    SHILPA VINOD

    in partial fu lf il lment for the award of the degree

    of

    BACHELOR OF ENGINEERING

    in

    ELECTRONICS AND COMMUNICATION ENGINEERING

    SREE NARAYANA GURUKULAM COLLEGE OF ENGINEERING,

    KADAYIRUPPU

    MG UNIVERSITY : KOTTAYAM

    MAY 2011

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    SREE NARAYANA GURUKULAM COLLEGE OF ENGINEERING

    KADAYIRUPPU

    Department of Electronics and Communication Engineering

    MINI PROJECT REPORT 2011

    CERTIFICATE

    Certified that this project report AUTOMATIC ROOM LIGHT

    CONTROLLER WITH BIDIRECTIONAL VISITOR COUNTER is the

    bona fide work of SARATH M.R., SARATH PRADEEP, and SHILPA

    VINODwho carried out the project work under my supervision.

    SIGNATURE SIGNATURE

    PROF. ARUMUGA SAMY MR. DEEPAK P

    Head of the Department Staff in Charge

    Electronics and Communication Asst. Professor

    Sree Narayana Gurukulam College Of Engineering Department of ECEKadayiruppu, Kolenchery

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    ACKNOWLEDGEMENT

    Before we get into the thick of things, we present our wholehearted compliments,

    with higher regards and warm thanks to one and all, who were the bone behind the

    sinews of this project.

    We give all glory and honour to Almighty God whose blessings and help

    made this endeavour a success.

    We wish to express our sincere thanks to our Principal, Dr.C.E.Krishnan, for

    providing an opportunity to undertake this project. We hereby acknowledge our

    sincere thanks to Prof. Arumuga Samy, our H.O.D. for his invaluable remarks and

    supervision in completing this project work successfully.

    Also we would like to express our boundless thanks and gratitude to Mr.

    Deepak P, Mr. Mahesh P S, Mr. Vishnu, Lecturers in ECE Dept. for their valuable

    guidance and suggestions in the whole course of our mini project activity.

    It would be unfair if we do not mention the invaluable contribution and

    timely co-operation extended by staff members of our dept.

    We would like to thank our Institution without which this project would

    have been a distant reality. We also extend our heartfelt thanks to our family and

    well wishers.

    Not the least, but the most, we are grateful to all the 6th semester

    students of this institution, our beloved companions for the inspiration and the co-

    operation they have shown at all levels of our work.

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    ABSTRACT

    This Project Automatic Room Light Controller with Bidirectional Visitor

    Counter 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 AT89S52

    continuously monitor the Infrared Receivers. When any object pass through the IR

    Receiver's then the IR Rays falling on the receivers are obstructed. This obstruction

    is sensed by the Microcontroller.

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    TABLE OF CONTENTS

    CHAPTER NO. TITLE PAGE NO.

    ABSTRACT 4

    LIST OF FIGURES

    1. Block Diagram of Circuit 82. Transmission Circuit 113. Receiver Circuit 134. Infrared Sensor 175. Block Diagram of TSOP 1738 186. Application Circuit 187. Timer IC (555) 188. LTS 542 (7-Segment Display) 209. LM7805 (Voltage Regulator) 2110.Relay Circuit 2211. Flow Chart 2312.

    Circuit Diagram in PCB 33

    1. INTRODUCTION 7

    2. BLOCK DIAGRAM DESCRIPTION 9

    2.1 Power Supply 9

    2.2 Enter and Exit Circuits 9

    2.3 89S52 Microcontroller 10

    2.4 Relay Driver Circuit 10

    3. CIRCUIT DESCRIPTION 11

    3.1 Transmission Circuit 12

    3.2 Receiver circuit 13

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    4. LIST OF COMPONENTS 14

    5. DESCRIPTION OF THE COMPONENTS USED 15

    5.1 Microcontroller AT89S52 15

    5.2 TSOP1738 17

    5.3 555 (TIMER IC) 18

    5.4 LTS 542 20

    5.5 LM7805 21

    5.6 Relay Circuit 22

    6. FLOW CHART 23

    7. PROGRAM 24

    8. PCB FABRICATION 28

    9. CONCLUSION 34

    10. BIBLIOGRAPHY 35

    11. APPENDICES 36

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    INTRODUCTION

    Project title is AUTOMATIC ROOM LIGHT CONTROLLER WITH

    BIDIRECTIONAL VISITOR COUNTER.

    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.

    In 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.

    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.

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    BLOCK DIAGRAM

    7-SEGMENT DISPLAY

    ENTER

    SENSOR

    SIGNAL

    CONDITIONING

    EXIT

    SENSOR

    SIGNAL

    CONDITIONING A

    T

    8

    9

    S

    5

    2

    RELAYDRIVER

    LIGHT

    POWER

    SUPPLY

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    BLOCK DIAGRAM DESCRIPTION

    The basic block diagram of the bidirectional visitor counter with automatic light

    controller is shown in the above figure. Mainly this block diagram consists of the

    following essential blocks.

    1. Power Supply2. Entry and Exit sensor circuit3. AT89S52 micro-controller4. Relay driver circuit

    1. Power Supply:-Here we used +12V and +5V dc power supply. The main function of this block

    is to provide the required amount of voltage to essential circuits. +12V is given to

    relay driver. To get the +5V dc power supply we have used here IC 7805, which

    provides the +5V dc regulated power supply.

    2. Enter and Exit Circuits:-This is one of the main part of our project. The main intention of this block is to

    sense the person. For sensing the person we are using a TSOP 1738 sensor. By

    using this sensor and its related circuit diagram we can count the number of

    persons.

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    3. 89S52 Microcontroller:-It is a low-power, high performance CMOS 8-bit microcontroller with 8KB of

    Flash Programmable and Erasable Read Only Memory (PEROM). The device is

    manufactured using Atmels high-density nonvolatile memory technology and is

    compatible with the MCS-51TM instruction set and pin out. The on-chip Flash

    allows the program memory to be reprogrammed in-system or by a conventional

    nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash

    on a monolithic chip, the Atmel AT89S52 is a powerful Microcontroller, which

    provides a highly flexible and cost effective solution for many embedded control

    applications.

    4. Relay Driver Circuit:-This block has the potential to drive the various controlled devices. In this block

    mainly we are using the transistor and the relays. One relay driver circuit we are

    using to control the light. Output signal from AT89S52 is given to the base of the

    transistor, which energizes the particular relay, because of this, appropriate device

    is selected and which performs its allotted function.

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    CIRCUIT DESCRIPTION

    There are two main parts of the circuits.

    1. Transmission Circuit (Infrared LEDs)2. Receiver Circuit (Sensors)

    1. Transmission Circuit:

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    This circuit diagram shows how a 555 timer IC, configured to function as a basic

    astable multivibrator. The astable multivibrator generates a square wave, the period

    of which is determined by the circuit external to IC 555. The astable multivibrator

    does not require any external trigger to change the state of the output. Hence the

    name free running oscillator. The time during which the output is either high or

    low is determined by the two resistors and a capacitor which are externally

    connected to the 555 timer.

    IR Transmission circuit is used to generate the modulated 36 kHz IR signal.

    The IC555 in the transmitter side is to generate 36 kHz square wave. Adjust the

    preset in the transmitter to get a 38 kHz signal at the o/p. Then you point it over the

    sensor and its o/p will go low when it senses the IR signal of 38 kHz.

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    2. Receiver Circuit:

    The IR transmitter will emit modulated 38 kHz IR signal and at the receiver

    we use TSOP1738 (Infrared Sensor). The output goes high when there is an

    interruption and it return back to low after the time period determined by the

    capacitor and resistor in the circuit i.e. around 1 second. CL100 is to trigger the

    IC555 which is configured as monostable multivibrator. Input is given to the Port 1

    of the microcontroller. Port 0 is used for the 7-Segment display purpose. Port 2 is

    used for the Relay Turn On and Turn off Purpose.LTS 542 (Common Anode) is

    used for 7-Segment display and that time Relay will get voltage and triggered, so

    light will get voltage and it will turn on and when counter will be 00 and at that

    time Relay will be turned off. Reset button will reset the microcontroller

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    LIST OF COMPONENTS

    MicrocontrollerAT89S52 IC7805 SensorTSOP 1738 (Infrared Sensor) Transformer12-0-12, 500 mA Preset4.7K Disc capacitor104,33pF Reset button switch Rectifier diodeIN4148 TransistorBC 547, 2N2222 7-Segment Display

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    DESCRIPTION OF THE COMPONENTS USED

    1. Microcontroller AT89S52The AT89S52 is a low-power, high-performance CMOS 8-bit

    microcontroller with 8K bytes of in-system programmable Flash memory. The

    device is manufactured using Atmels high-density nonvolatile memory

    technology and is compatible with the Industry-standard 80C51 instruction set and

    pin out. The on-chip Flash allows the program memory to be reprogrammed in-

    system or by a conventional nonvolatile memory pro-grammar. By combining a

    versatile 8-bit CPU with in-system programmable Flash on a monolithic chip, the

    Atmel AT89S52 is a powerful microcontroller which provides a highly-flexible

    and cost-effective solution to many embedded control applications.

    The AT89S52 provides the following standard features: 8K bytes of Flash,

    256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit

    timer/counters, a six-vector two-level interrupt architecture, a full duplex serial

    port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 is designed

    with static logic for operation down to zero frequency and supports two software

    selectable power saving modes. The Idle Mode stops the CPU while allowing the

    RAM, timer/counters, serial port, and interrupt system to continue functioning. The

    Power-down mode saves the RAM contents but freezes the oscillator, disabling all

    other chip functions until the next interrupt or hardware reset.

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    FEATURES:

    8 KB Reprogrammable flash. 32 Programmable I/O lines. 16 bit Timer/Counter3. 8 Interrupt sources. Power range: 4V5.5V Endurance : 1000 Writes / Erase cycles Fully static operation: 0 Hz to 33 MHz Three level program memory lock Power off flag Full duplex UART serial channel Low power idle and power down modes Interrupt recovery from power down modes 256 KB internal RAM Dual data pointer

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    2. TSOP1738 (INFRARED SENSOR)

    Fig. Infrared Sensor

    Description:

    The TSOP17..Series are miniaturized receivers for infrared remote control

    systems. PIN diode and preamplifier are assembled on lead frame, the epoxy

    package is designed as IR filter. The demodulated output signal can directly be

    decoded by a microprocessor. TSOP17.. is the standard IR remote control receiver

    series, supporting all major transmission codes.

    Features:

    Photo detector and preamplifier in one package Internal filter for PCM frequency Improved shielding against electrical field disturbance TTL and CMOS compatibility Output active low Low power consumption High immunity against ambient light Continuous data transmission possible (up to 2400 bps) Suitable burst length .10 cycles/burst

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    Block Diagram:

    Fig. Block Diagram of TSOP 173

    Application Circuit:

    Fig. Application circuit

    3. 555 (TIMER IC)

    Fig. Timer IC (555)

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    Description:

    The LM555 is a highly stable device for generating accurate time delays

    or oscillation. Additional terminals are provided for triggering or resetting if

    desired. In the time delay mode of operation, the time is precisely controlled by

    one external resistor and capacitor. For astable operation as an oscillator, the free

    running frequency and duty cycle are accurately controlled with two external

    resistors and one capacitor. The circuit may be triggered and reset on falling

    waveforms, and the output circuit can source or sink up to 200mA or drive TTL

    circuits.

    Features:

    Direct replacement for SE555/NE555 Timing from microseconds through hours Operates in both astable and monostable modes Adjustable duty cycle Output can source or sink 200 mA Output and supply TTL compatible Temperature stability better than 0.005% per C Normally on and normally off output Available in 8-pin MSOP package

    Applications:

    Precision timing Pulse generation Sequential timing

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    Time delay generation Pulse width modulation Pulse position modulation Linear ramp generator

    4. LTS 542 (7-Segment Display)

    Description:

    The LTS 542 is a 0.52 inch digit height single digit seven-segment display.

    This device utilizes Hi-eff. Red LED chips, which are made from GaAsP on GaP

    substrate, and has a red face and red segment.

    Fig. 7 Segment Display

    Features:

    Common Anode 0.52 Inch Digit Height

    Continuous Uniform Segments Low power Requirement Excellent Characters Appearance High Brightness & High Contrast Wide Viewing Angle

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    5. LM7805 (Voltage Regulator)

    Fig. Voltage Regulator

    Description:

    The KA78XX/KA78XXA series of three-terminal positive regulator

    are available in the TO-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 candeliver 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.

    Features:

    Output Current up to 1A Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24V Thermal Overload Protection Short Circuit Protection Output Transistor Safe Operating Area Protection

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    6. RELAY CIRCUIT:

    Fig. Relay

    A single pole dabble throw (SPDT) relay is connected to port RB1 of the

    microcontroller through a driver transistor. The relay requires 12 volts at a current

    of around 100ma, which cannot be provided by the microcontroller. So the driver

    transistor is added. The relay is used to operate the external solenoid forming part

    of a locking device or for operating any other electrical devices. Normally the relay

    remains off. As soon as pin of the microcontroller goes high, the relay operates and

    releases. Diode D2 is the standard diode on a mechanical relay to prevent back

    EMF from damaging Q3 when the relay releases.

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    FLOW CHART

    Fig. Flow Chart

    If the sensor 1 is interrupted first then the microcontroller will look forthe sensor 2, and if it is interrupted then the microcontroller will

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    increment the count and switch on the relay, if it is first time

    interrupted.

    If the sensor 2 is interrupted first then the microcontroller will look forthe sensor 1, and if it is interrupted then the microcontroller will

    decrement the count.

    When the last person leaves the room then counter goes to 0 and thattime the relay will turn off, and light will be turned off.

    PROGRAM

    // Program to make a bidirectional visitor counter using IR sensor#include

    #define msec 1

    unsignedint num=0;

    sbit dig_ctrl_4=P2^6; //declare the control pins of seven segmentssbit dig_ctrl_3=P2^5;

    sbit dig_ctrl_2=P2^6;sbit dig_ctrl_1=P2^5;

    sbit relay1 = P2^0;sbit pin = P3^7;

    unsignedchar

    digi_val[11]={0xFE,0x18,0x6D,0x3d,0x1B,0X37,0x77,0x1C,0xfF,0x3F};unsignedint dig_1,dig_2,dig_3,dig_4,test=0;

    unsignedchardig_disp=0;

    sbit up=P1^0; //up pin to make counter count up

    sbit down=P1^1; //down pin to make counter count down

    void delay(int x)

    {chary = 200;

    pin = !pin;while((x--))

    {

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    while((y--));

    }}

    void init() // to initialize the output pins and Timer0{

    up=down=1;dig_ctrl_4 = 0;

    dig_ctrl_3 = 0;dig_ctrl_2 = 0;

    dig_ctrl_1 = 0;

    relay1 = 0;TMOD=0x01;

    TL0=0xf6;

    TH0=0xFf;IE=0x82;TR0=1;

    P0=0x00;

    }

    void delay1() //To provide a small time delay

    {TMOD=0x01;

    TL0=0x36;

    TH0=0xF6;TR0=1;

    while(TF0==0);TR0=0;

    TF0=0;

    }

    void display() interrupt 1 // Function to display the digits on seven segment. For

    more details refer seven segment multiplexing.

    {TL0=0x36;

    TH0=0xf6;

    P0=0xFF;dig_ctrl_1 = dig_ctrl_3 = dig_ctrl_2 = dig_ctrl_4 = 0;

    dig_disp++;dig_disp=dig_disp%2;

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    switch(dig_disp)

    {

    case 0:

    P0= ~digi_val[dig_1];dig_ctrl_1 = 1;

    break;

    case 1:P0= ~digi_val[dig_2];

    dig_ctrl_2 = 1;

    break;

    case 2:

    P0= ~digi_val[dig_3];dig_ctrl_3 = 1;break;

    case 3:P0= ~digi_val[dig_4];

    dig_ctrl_4 = 1;

    break;}

    }

    void main()

    {unsigned int cnt=0;

    init();

    relay1 = 0;

    dig_ctrl_2 = 0;dig_ctrl_1 = 0;

    cnt = 0;relay1 = 1;

    delay(100);

    relay1 = 0;delay(100);

    while(1){

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    if(up==1)

    {cnt=0;

    delay(1000);

    if(down==1){

    if(test0)test--;if(test == 0) { relay1 = 0; }

    dig_2=test%10;

    dig_1=test/10;}

    }

    }}

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    PCB FABRICATION

    Printed Circuit Board (PCB) is piece of art. The performance of an electronic

    circuit depends on the layout and the design of PCB. A PCB mechanically supports

    and connects components by conductive pathways, etched from copper sheetslaminated on to insulated substrate. PCB ape used to rotate electrical currents andsignals through copper tracts which are firmly bonded to an insulating base.

    PCB Fabrication involves the following steps:

    1. Drawing the layout of the PCB in the paper. The track layout of theElectronic circuit should be made in such manner that the paths are in easy

    routes. It is then transferred to a Mylar sheet. The sheet is then touched with

    black ink.

    2. The solder side of the Mylar sheet is placed on the shiny side of the five-Star sheet and is placed in a frame. Then it is exposed to sunlight with Mylar

    sheet facing the sunlight.

    3. The exposed five- star sheet is put in Hydrogen Peroxide solution. Then it isput in hot water and shook till unexposed region becomes transparent.

    4. This is put in cold water and then the rough side is stuck on to the silkscreen. This is then pressed and dried well.

    5. The plastic sheet of the five-star sheet is removed leaving the pattern on thescreen.

    6. A copper clad sheet is cut to the size and cleaned. This is placed underscreen.

    7. As it resistant ink if spread on the screen so that a pattern of tracks and a padis obtained on a copper clad sheet. It is then dried.

    8. The dried sheet is then etched using Ferric chloride solution (32Baume) tillall the unwanted Copper is etched away. Swish the board to keep each fluid

    moving. Lift up the PCB and check whether all the unwanted Copper is

    removed. Etching is done by immersing the marked copper clad in FerricChloride solution after that the etched sheet is dried.

    9. The unwanted resist ink is removed using Sodium Hydroxide solution Holesare them dried.

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    PCB PARAMETERS

    Copper thickness - 72mil (1mm=39.37 mils)Track width - 60mil

    Clearance - 60milPad width - 86mil

    Pad height - 86milPad shape - Oval

    Pad hole size - 25milOn board - Through

    Hole size - 0.9mm (36mil)Base - Paper phenolic, Hylam

    PCB Quality - FRC4

    SOLDERING

    Soldering is the process of joining metals by using lower melting point to

    weld or alloy with joining surface.

    SOLDER

    Solder is the joining material that melts below 427 degree connections

    between components. The popularly used solders are alloys of tin (Sn) and lead(Pb) that melts below the melting point of tin.

    Types:

    1. Rosin core: - 60/40 Sn/Pb solders are the most common types used forelectronics assembly. These solders are available in various diameters andare most appropriate for small electronics work (0.02-0.05 dia is

    recommended)

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    2. Lead free: - lead free solders are used as more environmental-friendlysubstitutes for leaded solder, but they are typically not as easy to use mainly

    because of their higher melting point and poorer wetting properties.

    3. Silver: - Silver solders are typically used for low resistance connections butthey have a higher melting point and are expensive than Sn/ Pb solders.

    4. Acidcore: - Acid-core solders should not be used for electronics. They areintended for plumbing or non-electronics assembly work. The acid-core flux

    will cause corrosion of circuitry and can damage components.

    5. Other special solders :-

    Various melting point eutectics: These special solders aretypically used for non-electronic assembly of difficult to

    construct mechanical items that must be assembled in a particular

    sequence.

    Paste solders: These solders are used in the field application or inspecialized manufacturing application.

    FLUX

    In order to make the surface accept the solder readily, the componentsterminals should be free oxides and other obstructing films. The lead should be

    cleaned chemically or by abrasion using blades or knives.

    Small amount of lead coating can be done on the portion of the leads usingsoldering iron. This process is called thinning. Zinc chloride or ammoniumchloride separately or in combination is mostly used as fluxes. These are available

    in petroleum jelly as paste flux.

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    Flux medium used to remove the degree of wetting. The desirable properties of

    flux are:-

    It should provide a liquid cover over the materials and exclude airgap up to the soldering temperature.

    It should dissolve any Oxide on the metal surface. It should be easily replaced from the metal by the molten soldering

    operation

    Residue should be removable after completing soldering operation.

    The most common flux used in hand soldering of electronic components is

    rosin, a combination of mild organic acids extracted from pine tree.

    SOLDERING IRON

    It is a tool used to melt the solder and apply it at the joints in the circuit. It

    operates in 230V supply. The iron at the tip gets heated while few minutes. The

    50W and 25W soldering irons are commonly used for soldering of electronics

    circuit.

    SOLDERING STEPS

    1. Make the layout of the component in the circuit. Plug in the chord of thesoldering iron the mains to get heated.

    2. Straighten and clean the component leads using a blade or a knife.3. Mount the components on the PCB by bending the leads of the

    components. Use nose pliers.

    4. Apply flux on the joints and solder the joints. Soldering must be inminimum time to avoid dry soldering and heating up of the components.

    5. Wash the residue using water and brush.6. Solder joins should be inspected when completed to determine if they

    have been properly made.

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    CHARACTERISTICS OF A GOOD SOLDER JOINTS:

    A.Shiny surface.B.Good, smooth fillet.

    CHARACTERISTICS OF A POOR SOLDER JOINTS:

    1. Dull or crystallized surface: This is an indicator of a cold solder joint.Cold solder joint result from moving the component after soldering has

    been removed, but before the solder has hardened. Cold solder joints may

    work at first, but will eventually fail.

    2. Air pocket: Air pocket (voids) result from incomplete wetting of surface,allowing air to be in contact with the connecting metals. This will causeoxidation of the joints and eventual failure. Blow holes can occur due to

    vaporization of the moisture on the surface of the board and existing

    through the molten solder. Boards should be clean and dry. Prior to

    soldering. Ethanol (100%) can be used as a moisture chaser if boards are

    wet prior to soldering.

    3. Dimples: Dimples in the surface do not always indicate a seriousproblem, but they should be avoided since they are precursors to voids.

    4.

    Floaters: Black spots floating in the soldering fillet should be avoidedbecause they indicate contamination and a potential for failure as in the

    case of voids. These black spots usually result from overheated (burnt)

    Rosin or other contaminants such as burnt wire insulation. Maintaining a

    clean tip will help to avoid these problems.

    5. Balls: A solder balls, instead of a fillet can occur if the trace was heatedbut the leads was not (vice versa). This prevents proper wetting of both

    surfaces and result in solder being attached to only one surface

    (component or trace)

    6. Excess solder: Excess solder usage can cover up other potential problemsand should be avoided. It can lead to solder bridges. In addition, spherical

    solder joints can result from the application of too much solder.

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    CIRCUIT DIAGRAM IN PCB

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    CONCLUSION

    Hereby we come to the end of our project AUTOMATIC ROOM LIGHTCONTROLLER WITH BIDIRECTIONL VISITOR COUNTER.

    Application of this project For counting purposes For automatic room light control

    Advantages of this project Low cost Easy to use Implement in single door

    Future Expansion By using this circuit and proper power supply we can implement various

    applications such as fans, tube lights, etc.

    By modifying this circuit and using two relays we can achieve a task ofopening and closing the door.

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    BIBLIOGRAPHY

    Reference Books Programming in ANSI C: E BALAGURUSAMY The 8051microcontroller and embedded systems:

    MUHAMMAD ALI MAZIDI

    JANICE GILLISPIE MAZIDI

    The 8051 microcontroller: KENNETH J. AYALA

    Website www.datasheets4u.com www.datasheetcatalog.com www.8051.com

    http://www.datasheets4u.com/http://www.datasheets4u.com/http://www.datasheetcatalog.com/http://www.datasheetcatalog.com/http://www.8051.com/http://www.8051.com/http://www.8051.com/http://www.datasheetcatalog.com/http://www.datasheets4u.com/
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    APPENDICES

    Datasheets of ICs used:

    AT89S52 LM555 IC 7805 TSOP 1738