1. 1
CHAPTER 1- INTRODUCTION OF PROJECT [1,3]
This circuit has been designed solely for the security purpose. This circuit contains two infrared
sensors (IR sensors), a LCD screen for the display and a buzzer section. The two IR sensors refer
to the first and the second security levels.
When there is an obstacle between the transmitter and receiver of first IR sensor then an alert is
shown on the LCD screen and at the same instance of time, the buzzer beeps till the typing is
finished on screen.
When the obstacle is placed between the second IR sensor then the LCD screen shows the High
alert message which describes that the second security level has been broken too and buzzer
beeps more loudly and for a longer duration of time.
The whole system runs on a power supply of 9V which is provided by a battery. There are no
other ICs in this system other than the micro-controller.
This project is a simple demonstration of a security system. It shows that how we can create a
security system with lesser amount of components i.e. by keeping the circuits simple. The
circuitry is quite simple and the process is easy to understand. Moreover, this project shows the
value of an IR sensor and how important they can be.

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CHAPTER 2 – PRINCIPLE AND WORKING [1,4]
PRINCIPLE
This device emits and/or detects infrared radiation to sense a particular phase in the environment.
Generally, thermal radiation is emitted by all the objects in the infrared spectrum. The infrared
sensor detects this type of radiation which is not visible to human eye.
The basic idea is to make use of IR LEDs to send the infrared waves to the object. Another IR
diode of the same type is to be used to detect the reflected wave from the object. When IR
receiver is subjected to infrared light, a voltage difference is produced across the leads. Less
voltage which is produced can be hardly detected and hence operational amplifiers(Op-Amp) are
used to detect the low voltages accurately.
Measuring the distance of the object from the receiver sensor: The electrical property of IR
sensor components can be used to measure the distance of an object. The fact when IR receiver is
subjected to light, a potential difference is produced across the leads.
The microcontroller AT89C51 is the brain of the project. When battery is connected to the
snapper circuit then current starts flowing and the system gets on. The microcontroller is
interfaced with LCD, IR section and the buzzer section. As soon as an IR sensor breaks, the
system gets activated and according to the code the LCD shows the message and the buzzer
starts beeping

3. 3
WORKING
1-FIRST SECURITY LEVEL
When there is an obstacle between the transmitter and receiver of first IR sensor then an alert is
shown on the LCD screen and at the same instance of time, the buzzer beeps till the typing is
finished on screen.
As the transmitter and receiver are in a direct line, the interruption in the dignal cause the LCD to
glow and buzzer to emit sound.
3.2-SECOND LEVEL SECURITY
When the obstacle is placed between the second IR sensor then the LCD screen shows the High
alert message which describes that the second security level has been broken too and buzzer
beeps more loudly and for a longer duration of time.The security system stops if the reset button
is pressed.

4. 4
CHAPTER 3- CIRCUIT DIAGRAM AND BLOCK DIAGRAM [2,3,4]
FIGURE 1 – A SIMPLE IR SENSORS
FIGURE 2- IR SENSORS CIRCUIT

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FIGURE 3- IR Sensor with AT89C51

6. 6
FIGURE 4- A LCD interfacing with AT89C51
FIGURE 5- Buzzer Interfacing

7. 7
CHAPTER 4- COMPONENTS DETAILS & SPECIFICATIONS
SerialNumber Component Name Circuit Notation Description
1 Atmel 89C51 Microcontroller
2 JHD216 LCD
3 IR Sensor (2) IR Module
4 HXD Buzzer
5 Transistor Q1
6 110592 Crystal Oscillator
7 IC 7805 Voltage Regulated IC
9 Resistor (270 Ω) R1
9 Resistor (10 KΩ) R2
10 Resistor (10 KΩ) R3
11 Resistor (270 Ω) R4
12 Capacitor(33pF) C1
13 Capacitor(33pF) C2
14 Capacitor(10µF) C3
15 LED (3) LED 1 For indication purpose
16 Push Switch For Reset
17 Potentiometer Adjust LED Brightness
18 6F22 Battery 9V Power Supply
Table -1 component required .

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COMPONENTSPECIFICATIONS[1,2,3]
4.1 AT89C51 MICROCONTROLLER
AT89C51 is an 8-bit microcontroller and belongs to Atmel's 8051 family. ATMEL 89C51 has
4KB of Flash programmable and erasable read only memory (PEROM) and 128 bytes of RAM.
It can be erased and program to a maximum of 1000 times.
In 40 pin AT89C51, there are four ports designated as P1, P2, P3 and P0. All these ports are 8-bit
bi-directional ports, i.e., they can be used as both input and output ports. Except P0 which needs
external pull-ups, rest of the ports have internal pull-ups. When 1s are written to these port pins,
they are pulled high by the internal pull-ups and can be used as inputs.
Port P0 and P2 are also used to provide low byte and high byte addresses, respectively, when
connected to an external memory. Port 3 has multiplexed pins for special functions like serial
communication, hardware interrupts, timer inputs and read/write operation from external
memory. AT89C51 has an inbuilt UART for serial communication. It can be programmed to
operate at different baud rates. Including two timers & hardware interrupts, it has a total of six
interrupts.

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Fig. 6- AT89C51 Pin Diagram
4.2 IR MODULE
Infrared (IR) light is electromagnetic radiation with longer wavelengths than those of visible
light, extending from the nominal red edge of the visible spectrum at 0.74 micrometres (µm) to
300 µm. This range of wavelengths corresponds to a frequency range of approximately 1 to
400 THz, and includes most of the thermal radiation emitted by objects near room temperature.
Infrared light is emitted or absorbed by molecules when they change their rotational-vibrational
movements.
Fig. 7- IR Module

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4.3 BUZZER
A buzzer or beeper is an audio signaling device, which may be mechanical, electromechanical,
or piezoelectric.Typical uses of buzzers and beepers include alarm devices, timers and
confirmation of user input such as a mouse click or keystroke.
Fig.8- Buzzer
4.4 LCD
LCD (Liquid Crystal Display) is used in all the electronics projects to display the status of the
process. A 16x2 alphanumeric LCD is most widely used module of LCD nowadays. There are
several others type of LCD available in market also.
The reason for choosing LCD over other display component or devices is that it is
 Low cost
 Easily programmable
 Large number of display character etc.

11. 11
Fig.9- LCD
4.5 CRYSTAL OSCILLATOR
A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a
vibrating crystal of piezoelectric material to create an electrical signal with a very
precise frequency. This frequency is commonly used to keep track of time (as in quartz
wristwatches), to provide a stable clock signal for digital integrated circuits, and to stabilize
frequencies for radio transmitters and receivers. The most common type of piezoelectric
resonator used is the quartz crystal, so oscillator circuits designed around them became known as
"crystal oscillators."
Fig.10- Crystal Oscillator

12. 12
4.6:7805 IC
7805 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed linear voltage
regulator ICs. The voltage source in a circuit may have fluctuations and would not give the fixed
voltage output. The voltage regulator IC maintains the output voltage at a constant value. The xx
in 78xx indicates the fixed output voltage it is designed to provide. 7805 provides +5V regulated
power supply. Capacitors of suitable values can be connected at input and output pins depending
upon the respective voltage levels.
Fig.11- 7805 IC
4.7 RESISTOR
A resistor is a two-terminal electronic component that produces a voltage across its terminals
that is proportional to the electric current through it in accordance with Ohm's law:
V = IR
Fig.12- Resistor

13. 13
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).
4.8 CAPACITOR
A capacitor (formerly known as condenser) is a passive electronic component consisting of a pair
of conductors separated by a dielectric (insulator). When there is a potential difference (voltage)
across the conductors, a static electric field develops in the dielectric that stores energy and
produces a mechanical force between the conductors. An ideal capacitor is characterized by a
single constant value, capacitance, measured in farads.
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.
Fig.13- Capacitor

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CHAPTER 5- PCB LAYOUT [1,2]
FIGURE 14- Two Level Security System Using IR sensors

15. 15
CHAPTER 6- SOLDERING AND DESOLDERING [5,6]
Soldering is a process in which two or more metal items are joined together by
melting and flowing a filler metal (solder) into the joint, the filler metal having a
lower melting point than the adjoining metal. Soldering differs from welding in
that soldering does not involve melting the work pieces. In brazing, the filler metal
melts at a higher temperature, but the work piece metal does not melt. In the past,
nearly all solders contained lead, but environmental concerns have increasingly
dictated use of lead-free alloys for electronics and plumbing purposes.
FIGURE 15 – Desoldering a contact from a wire.
Common solder formulations based on tin and lead are listed below. The fraction
represent percentage of tin first, then lead, totaling 100%:
 63/37: melts at 183 °C (361 °F) (eutectic: the only mixture that melts at a
point, instead of over a range)
 60/40: melts between 183–190 °C (361–374 °F)
 50/50: melts between 185–215 °C (365–419 °F)
The purpose of flux is to facilitate the soldering process. One of the obstacles to a
successful solder joint is an impurity at the site of the joint, for example, dirt, oil or
oxidation. The impurities can be removed by mechanical cleaning or by chemical
means, but the elevated temperatures required to melt the filler metal (the solder)
encourages the work piece (and the solder) to re-oxidize. This effect is accelerated
as the soldering temperatures increase and can completely prevent the solder from
joining to the work piece. One of the earliest forms of flux was charcoal, which

16. 16
acts as a reducing agent and helps prevent oxidation during the soldering process.
Some fluxes go beyond the simple prevention of oxidation and also provide some
form of chemical cleaning (corrosion).
Fluxes for soft solder are currently available in three basic formulations:
1. Water-soluble fluxes - higher activity fluxes designed to be removed with
water after soldering (no VOCs required for removal).
2. No-clean fluxes - mild enough to not "require" removal due to their non-
conductive and non-corrosive residue. These fluxes are called "no-clean"
because the residue left after the solder operation is non-conductive and
won't cause electrical shorts;nevertheless they leave a plainly visible white
residue that resembles diluted bird-droppings. No-clean flux residue is
acceptable on all 3 classes of PCBs as defined by IPC-610 provided it does
not inhibit visual inspection, access to test points, or have a wet, tacky or
excessive residue that may spread onto other areas. Connector mating
surfaces must also be free of flux residue. Finger prints in no clean residue is
a class 3 defect.
3. Traditional rosin fluxes - available in non-activated (R), mildly activated
(RMA) and activated (RA) formulations. RA and RMA fluxes contain rosin
combined with an activating agent, typically an acid, which increases the
wettability of metals to which it is applied by removing existing oxides. The
residue resulting from the use of RA flux is corrosive and must be cleaned.
RMA flux is formulated to result in a residue which is not significantly
corrosive, with cleaning being preferred but optional.
Flux performance needs to be carefully evaluated; a very mild 'no-clean' flux might
be perfectly acceptable for production equipment, but not give adequate
performance for a poorly controlled hand-soldering operation.
DESOLIDERING
In electronics, desoldering is the removal of solder and components from a circuit
board for troubleshooting, repair, replacement, and salvage. Specialized tools,
materials, and techniques have been devised to aid in the desoldering process.

17. 17
FIGURE 16-Solders can be removed using a
vacuum plunger (on the right) and a soldering iron.
Desoldering tools and materials include the following:
 Solder wick
 Heat guns, also called hot air guns
 Desoldering pump
 Removal alloys
 Removal fluxes
 Heated soldering tweezers
 Various picks and tweezers for tasks such as pulling at, holding, removing, and
scraping components.
 Vacuum and pressurepumps with specialized heater tips and nozzles
 Rework stations, used to repair printed circuit board assemblies that fail factory
test.
Terminology is not totally standardised. Anything with a base unit with provision
to maintain a stable temperature, pump air in either direction, etc., is often called a
"station" (preceded by rework, soldering, desoldering, hot air); one, or sometimes
more, tools may be connected to a station, e.g., a rework station may accommodate
a soldering iron and hot air head. A soldering iron with a hollow tip and a spring-,
bulb-, or electrically-operated suction pump may be called a desoldering
iron. Terms such as "suction pen" may be used; the meaning is usually clear from
the context.

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CHAPTER 7- APPLICATIONS [2,4]
The various applications of this project is listed as
 In shopping malls, jewelers , museums ,..etc
 In home security systems.
 In burglar alarm/alert system
 In trespassersecurity system
 In remote controls for DVD players and television.
 In industrial/commercial security systems,…etc

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CHAPTER 8- ADVANTAGE AND DISADVANTAGE [1,4]
Advantages-
1. Compatibility:95Khz is industry standard.
- Home receiver can be used with public transmitters.
- 250khz if high intensity lighting.
2. No spillover means society.
3. Can be used in adjacent rooms.
4. Widest bandwidth and best sound reproduction.
5. Appropriate for mind to moderate /server loss.
6. Not affected by radio transmission.
Disadvantages-
1. Receiver required for everyone.
2. Must have direct line of sight.
3.Can’t cover the receiver or put in pocket.
4. Indoor or evening use only.
5. High intensity or fluorescent lights cause interference.
6. Large areas require multiple emitter panels.
7. Quality varies with company.

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Conclusion
Security is the degree of resistance to, or protection from, harm. It
applies to any vulnerable and valuable asset, such as a person, dwelling,
community, nation, or organization.
As noted by the Institute for Security and Open Methodologies
(ISECOM) in the OSSTMM 3, security provides "a form of protection
where a separation is created between the assets and the threat." These
separations are generically called "controls," and sometimes include
changes to the asset or the threat.
Security alarms are used in residential, commercial, industrial, and
military properties for protection against burglary (theft) or property
damage, as well as personal protection against intruders. Car alarms
likewise protect vehicles and their contents. Prisons also use security
systems for control of inmates.

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References
[1].www.osstmm.org
[2].http;//en.wikipedia/wiki/security_system
[3].www.egr.msu.edu
[4].www.twandik.free.fr.com
[5].http://en.wikipedia.org/wiki/Soldering.
[6]. http://en.wikipedia.org/wiki/Desoldering.