AUTOMATIC ROOM LIGHT CONTROLLER WITH
BIDIRECTIONAL VISITOR COUNTER
A PROJECT REPORT
Submitted by
1. Rathod Tushar (086030311091)
2. Patel Vijal
(096030311023)
3. Patel Nishchint (09603031105)
in partial fulfillment for the award of the diploma
of
ENGINEERING
in
ELECTRONICS AND COMMUNICATION ENGINEERING
ATMIYA INSTITUTE OF TECHNOLOGY & SCEINCE FOR DIPLOMA
STUDIES, RAJKOT
1
GUJARAT TECHNOLOGY UNIVERCITY
[2012 -2013]
A
Project Report
On
Automatic Room Light & Visitor Counter
In partial fulfillment of requirements for the degree of
Diploma of Engineering
In
EC Engineering
Under the Guidance of
Mr. Dhaval Sheth
Submitted By:
1. Rathor Tushar - 086030311091
2. Patel Vijal 096030311023
3. Patel Nishchint -096030311105
DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING
ATMIYA INSTITUTE OF TECHNOLOGY AND SCIENCE FOR
DIPLOMA STUDIES, RAJKOT- 360005.
[2012 – 2013]
2
CERTIFICATE
This is to certify that the project entitled “Automatic Room Light & Visitor
Counter ” has been carried out by the team under my guidance in partial fulfillment
of the Diploma of Engineering in Electronics & Communication in GTU during
the academic year 2012-2013 (Semester-5).
Team:
Patel Nishchint
Rathor Tushar
Patel Vijal
Date:
Place:
Guide
Head, EC Department
(Name of Guide)
Principal
External guide
3
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.G. C Joshi, for
providing an opportunity to undertake this project. We hereby acknowledge our
sincere thanks to Prof. D.M jethloja, 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.
Niraj Bhadhresha, Mr. Jigar Ratnottar, Mr. Mayur Patel, , Lecturers in ECE Dept.
for their valuable guidance and suggestions in the whole course of our 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.
4
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.
TUSHAR RATHOD
PATEL VIJAL
PATEL NISHCHINT
5
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 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 receivers are obstructed. This obstruction is sensed by the
Microcontroller.
6
TABLE OF CONTENTS
CHAPTER NO.
1.
TITLE
PAGE NO.
INTRODUCTION
9
LIST OF FIGURES
2.
3.
1. Block Diagram of Circuit
10
2. Transmission Circuit
13
3.
15
Receiver Circuit
4. Infrared Sensor
19
5. Block Diagram of TSOP 1738
20
6. Application Circuit
20
7. Timer IC (555)
20
8. LTS 542 (7-Segment Display)
22
9. LM7805 (Voltage Regulator)
23
10. Relay Circuit
24
11. Flow Chart
25
12. Circuit Diagram in PCB
35
BLOCK DIAGRAM DESCRIPTION
11
2.1 Power Supply
11
2.2 Enter and Exit Circuits
11
2.3 89C51 Microcontroller
12
2.4 Relay Driver Circuit
12
CIRCUIT DESCRIPTION
13
3.1 Transmission Circuit
13
3.2 Receiver circuit
15
7
4.
LIST OF COMPONENTS
16
5.
DESCRIPTION OF THE COMPONENTS USED
17
5.1 Microcontroller AT89C51
17
5.2 TSOP1738
19
5.3 555 (TIMER IC)
20
5.4 LTS 542
22
5.5 LM7805
23
5.6 Relay Circuit
24
6.
FLOW CHART
25
7.
PROGRAM
26
8.
PCB FABRICATION
30
9.
CONCLUSION
36
10.
BIBLIOGRAPHY
37
8
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 today’s 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.
9
BLOCK DIAGRAM
ENTER
SENSOR
SIGNAL
CONDITIONING
EXIT
SENSOR
SIGNAL
CONDITIONING
POWER
SUPPLY
LCD
-
10
A
T
8
9
C
5
1
RELAY
DRIVER
LIGHT
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 Supply
2. Entry and Exit sensor circuit
3. AT89C51 micro-controller
4. 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.
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
11
manufactured using Atmel’s 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 AT89C51 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 AT89C51 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.
12
CIRCUIT DESCRIPTION
There are two main parts of the circuits.
1. Transmission Circuit (Infrared LEDs)
2. Receiver Circuit (Sensors)
1. Transmission Circuit:
13
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
14
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.
15
2. Receiver Circuit:
Fig. 3.4 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 LCD 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
16
LIST OF COMPONENTS
 Microcontroller – AT89C51
 IC – 7805
 Sensor – TSOP 1738 (Infrared Sensor)
 Transformer – 12-0-12, 500 mA
 Preset – 4.7K
 Disc capacitor – 104,33pF
 Reset button switch
 Rectifier diode – IN4148
 Transistor – BC 547, 2N2222
 LCD
17
DESCRIPTION OF THE COMPONENTS USED
1. Microcontroller AT89C51:
The AT89C51 is a low-power, high-performance CMOS 8-bit
microcomputer with 4K bytes of Flash Programmable and Erasable Read
Only Memory (PEROM). The device is manufactured using Atmel’s high
density nonvolatile memory technology and is compatible with the industry
standard MCS-51™ 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 AT89C51 is a powerful
microcomputer which provides a highly flexible and cost effective solution
to many embedded control applications.
The AT89C51 provides the following standard features: 4K bytes of
Flash, 128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters, a five
vector two-level interrupt architecture, a full duplex serial port, on-chip
oscillator and clock circuitry. In addition, the AT89C51 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
hardware reset.
18
FEATURES:• Compatible with MCS-51™ Products
• 4K Bytes of In-System Reprogrammable Flash Memory
– Endurance: 1,000 Write/Erase Cycles
• Fully Static Operation: 0 Hz to 24 MHz
• Three-Level Program Memory Lock
• 128 x 8-Bit Internal RAM
• 32 Programmable I/O Lines
• Two 16-Bit Timer/Counters
• Six Interrupt Sources
• Programmable Serial Channel
• Low Power Idle and Power Down Modes
19
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
20
 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
Block Diagram:
Fig. Block Diagram of TSOP 173
Application Circuit:
21
Fig. Application circuit
3) 555 (TIMER IC):
Fig. Timer IC (555)
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.
22
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
 Time delay generation
 Pulse width modulation
 Pulse position modulation
 Linear ramp generator
4) LCD
Description:
A liquid crystal display (LCD) is a flat panel display, electronic visual display, or
video display that uses the light modulating properties of liquid crystals. Liquid
crystals do not emit light directly.
23
LCDs are available to display arbitrary images (as in a general-purpose computer
display) or fixed images which can be displayed or hidden, such as preset words,
digits, and 7-segment displays as in a digital clock. They use the same basic
technology, except that arbitrary images are made up of a large number of small
pixels, while other displays have larger elements.
LCDs are used in a wide range of applications including computer monitors,
televisions, instrument panels, aircraft cockpit displays, and signage. They are
common in consumer devices such as video players, gaming devices, clocks,
watches, calculators, and telephones, and have replaced cathode ray tube (CRT)
displays in most applications. They are available in a wider range of screen sizes
than CRT and plasma displays, and since they do not use phosphors, they do not
suffer image burn-in. LCDs are, however, susceptible to image persistence.[1]
Fig. LCD
Features:
•5
x 8 dots includes cursor
• Built-in controller (KS 0066 or Equivalent)
24
• + 5V power supply (Also available for + 3V)
• 1/16 duty cycle
• B/L to be driven by pin 1, pin 2 or pin 15, pin 16 or A and K (LED)
• N.V. optional for + 3V power supply
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 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.
Features:
 Output Current up to 1A
25

Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24V

Thermal Overload Protection

Short Circuit Protection

Output Transistor Safe Operating Area Protection
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.
26
FLOW CHART:
Fig. 4.7 Flow Chart
 If the sensor 1 is interrupted first then the microcontroller will look for
the sensor 2, and if it is interrupted then the microcontroller will
27
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 for
the 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 that
time the relay will turn off, and light will be turned off.
PROGRAM
#include<reg51.h>
#include<stdio.h>
#include<string.h>
#include<math.h>
void msdelay(unsigned int);
#define LCDdata P3
//Declaring LCDdata
sbit LCDrs = P2^0;
//The Register select Pin
sbit LCDrw = P2^1;
//The Read/Write Pin
sbit LCDen = P2^2;
//The Enable Pin
28
void condition1();
void condition2();
sbit sensor1 =P1^0;
sbit sensor2 =P1^1;
sbit light =P0^7;
unsigned int e=0;
unsigned char abc[4];
void msdelay(unsigned int itime)
{
unsigned int i,j;
for(i=0;i<itime;i++)
for(j=0;j<1275;j++);
}
void lcdcmd(unsigned char DATA)
{
29
LCDrs=0;
LCDrw=0;
LCDen=1;
//Strobe the enable pin
LCDdata = DATA;
//Put the value on the pins
LCDrs=0;
LCDrw=0;
LCDen=0;
}
void initialize(void)
{
lcdcmd(0x30);
//1 line and 5x7 matrix
msdelay(1);
lcdcmd(0x38);
//2 line and 5x7 matrix
msdelay(1);
lcdcmd(0x0c);
//Display on, cursor off
30
msdelay(1);
lcdcmd(0x01);
//Clear display Screen
msdelay(1);
lcdcmd(0x06);
//shift cursor to right
msdelay(1);
}
void lcddat(unsigned int DATA)
{
LCDrs = 1;
LCDrw = 0;
LCDen = 1;
LCDdata = DATA;
//Strobe the enable pin
//Put the value on the pins
LCDrs = 1;
LCDrw = 0;
LCDen = 0;
31
}
void display_lcd(unsigned char location, unsigned char *d)
{
lcdcmd(0x80 | location);
msdelay(1);
//10mS delay generation
while(*d)
{
lcddat(*d++);
msdelay(1);
//10mS delay generation
}
}
void main(void)
{
initialize();
P1=0xff;
32
P2=0x00;
P3=0x00;
light=1;
e=0;
while(1)
{
display_lcd(0x00,"visitor counter"); //Display character String from
location specified
display_lcd(0xc0,"count=");
location specified
if(sensor1==0)
condition1();
if(sensor2==1)
condition2();
33
//Display character String from
}
}
void condition1()
{
msdelay(50);
if(sensor2==0)
{
msdelay(50);
e=e+1;
if(e==1)
{
light=~light;
//return;
}
// lcdcmd(0x01);
//Clear display Screen
34
// msdelay(1);
//lcdcmd(0xc9);
//shift cursor to right
//msdelay(1);
//display_lcd(0x00,"visitor counter");
sprintf(abc,"%d",e);
display_lcd(0xc9,abc);
msdelay(100);
}
else
{
return;
}
}
void condition2()
{
35
msdelay(50);
if(sensor1==1)
{
msdelay(50);
e=e-1;
if(e==0)
{
light=~light;
}
sprintf(abc,"%d",e);
display_lcd(0xc9,abc);
msdelay(100);
return;
}
}
36
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 sheets
laminated on to insulated substrate. PCB ape used to rotate electrical currents and
signals 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 the
Electronic 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 fiveStar 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 is
put 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 silk
screen. This is then pressed and dried well.
5. The plastic sheet of the five-star sheet is removed leaving the pattern on the
screen.
6. A copper clad sheet is cut to the size and cleaned. This is placed under
screen.
7. As it resistant ink if spread on the screen so that a pattern of tracks and a pad
is obtained on a copper clad sheet. It is then dried.
8. The dried sheet is then etched using Ferric chloride solution (32Baume) till
all the unwanted Copper is etched away. Swish the board to keep each fluid
37
moving. Lift up the PCB and check whether all the unwanted Copper is
removed. Etching is done by immersing the marked copper clad in Ferric
Chloride solution after that the etched sheet is dried.
9. The unwanted resist ink is removed using Sodium Hydroxide solution Holes
are them dried.
PCB PARAMETERS
Copper thickness
Track width
Clearance
Pad width
Pad height
Pad shape
Pad hole size
On board
Hole size
Base
PCB Quality
- 72mil (1mm=39.37 mils)
- 60mil
- 60mil
- 86mil
- 86mil
- Oval
- 25mil
- Through
- 0.9mm (36mil)
- Paper phenolic, Hylam
- 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:
38
1. Rosin core: - 60/40 Sn/Pb solders are the most common types used for
electronics assembly. These solders are available in various diameters and
are most appropriate for small electronics work (0.02’’-0.05” dia is
recommended)
2. Lead free: - lead free solders are used as more environmental-friendly
substitutes 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 but
they have a higher melting point and are expensive than Sn/ Pb solders.
4. Acid –core: - Acid-core solders should not be used for electronics. They are
intended 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 are
typically 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
in specialized manufacturing application.
FLUX
In order to make the surface accept the solder readily, the components
terminals 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 using
soldering iron. This process is called thinning. Zinc chloride or ammonium
39
chloride separately or in combination is mostly used as fluxes. These are available
in petroleum jelly as paste flux.
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
air gap 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 the
soldering 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 in
minimum time to avoid dry soldering and heating up of the components.
40
5. Wash the residue using water and brush.
6. Solder joins should be inspected when completed to determine if they
have been properly made.
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 cause
oxidation 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 serious
problem, but they should be avoided since they are precursors to voids.
4. Floaters: Black spots “floating” in the soldering fillet should be avoided
because 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 heated
but 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)
41
6. Excess solder: Excess solder usage can cover up other potential problems
and should be avoided. It can lead to solder bridges. In addition, spherical
solder joints can result from the application of too much solder.
42
CIRCUIT DIAGRAM IN PCB
43
TRANSMITTER DIAGRAM
44
RECEIVER DIAGRAM
45
CONCLUSION
Here by we come to the end of our project “AUTOMATIC ROOM LIGHT
CONTROLLER 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 of
opening 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
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