Laser Intruder Alarm
Content
CHAPTER 1
INTRODUCTION
1.1 AIM OF THE PROJECT:
A alarm is a type of security equipment that can be used to safeguard homes and
property. If we love our home then buying burglar alarm should be our first priority when moving to a new home. Burglar crimes are continually rising with each passing day. Many have lost their homes and families through violent burglaries in many countries today. Some have lost what they considered precious and valuable to them. Things such as jewelry, vehicles, and clothes are huge investments to many.
During the olden days a watchman would be hired to take care of property and offer needed security in the home. Some homes also had fierce dogs that would be let out only at night. The two were supposed to provide security to our belongings even in the absence of the owner. However, hiring a watchman was not an effective method since most of them would be killed in the line of duty. Sometimes dogs would attack even visitors while some watchmen looted property. This led to the development of alarm equipments.
1.2 ABOUT THE CICUIT:
The circuit is divided into two parts i.e. the transmitter and the receiver part
Transmitter point:
The tranmitter circuit is othing but a laser diode driven by a battery connected to the diode through a series resistance R1. In order to ensure that the current through the diode remains constant irrespective of drop in battery voltage, a 3-terminal voltage regulator VR-1 has bee used. This regulator produces a constant 5V output as long as input remains equal to or more
1
than 7.5V thus ensuring a constant drive current for the laser diode. The drive current in this case would be(3500/47) mA. The laser diode here can be the one typically used in laser pointers emitting in red. This would be more economical than buying one. If the experiment so desires, we can use the laser pointer itself as a complete transmitter circuit. The pointer has in-built suitable series resistance and an ON/OFF switch and a battery. The given circuit would help when we want to go a step further and want to use infrared laser diode so as to get an invisible laser beam, which would be a requirement in any intruder alarm system, I recommend the use of laser pointer for the purpose of learning and demonstration.
Receiver part:
The receiver part basically comprises of a current to voltage converter section configured around IC1(OP AMP 356) feeding a positive edge triggered monoshot configuration buit around IC2(555 timer). The output of the monoshot feeds a buzzer that gives an audio beep during the time it get a high input from the timer IC 555. The receiver section operates from +5V DC generated from another 9V battery and 3 terminal regulator VR2. The battery can be connected to the circuit through switch SW2 The current-to-voltage converter section converts the photocurrent produced by the photodiode PD1 as a result of laser light falling on it into an equivalent vltage across resistor R2. This voltage gets amplified bya factor of 23 in the non-inverting amplifier provided by an OP-AMP and resistors R3,R4. So, when the laser light is falling on the photodiode, the opamp output is same DC voltage, The component values have been so chosen as to produce about 5V DC for a laser power of 0.5mW, typical of a laser pointer. Otherwise the amplifier gain can be adjusted to produce 5VDC.
1.3 ADVANTAGES OVER COMMERCIAL SECURITY SYSTEMS:
There are dozens of different security systems on the market that utilize lasers and can effectively protect everything from small apartments and businesses to large areas of property. Most home laser security systems consist of two parts: a basic alarm unit and an
2
infrared motion detector. Laser security systems of the past used to rely on connections wired to a keypad, requiring the customer to use special codes to arm and disarm the system. Since the majority of laser security systems are now wireless, the units can be turned on or off with a wireless remote or, in some models, by touch tone phone from anywhere in the world.
The basic sensing component of a modern laser security system is an infrared motion detector. An infrared motion detector works by using beams of infrared light to detect changes in heat which is absent in most of the commercial security systems. Laser alarm systems provides the state of the art features and benefits of a conventional monitored alarm system. Laser alarm systems is an advanced and effective security system that does the job right. Laser alarm systems can be activated in seconds without programming, installation, in-home sales people and technicians; and with no hassle, mess, or waiting. There are no hidden costs, no on-going service calls and costs, and Rapid Response Monitoring Service provides the most technologically advanced monitoring service available. All at a fraction of the cost of other major brands. Laser alarm systems is perfect for homes, condos, apartments, small offices, and retail stores.
Laser security systems have many advantages. They are simple to install and can be used effectively inside or outside a home. The systems can be used as a highly effective perimeter alarm for property boundaries or even for pools, where customers can have the lasers set to detect when small children come within a set number of feet from the edge of the water. Indoors, the sensors utilize normal power outlets and telephone jacks; outdoors, the sensors can be hidden beneath plants and bushes and will not harm lawns or other vegetation. However, laser security systems can be prohibitively expensive. While some security system plans allow for customers to target one room, plans that protect large amounts of land or an entire house will cost much more and can be difficult for many customers to afford .
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CHAPTER 2 BLOCK DIAGRAM AND EXPLANATION
2.1 BLOCK DIAGRAM:
Block diagram
2.2 BLOCK DIAGRAM EXPLANATION 2.2.1 Laser Diode/Pointer:
The laser diode is a laser where the active medium is a semiconductor similar to that found in a light-emitting diode. The most common type of laser diode is formed from a p-n junction and powered by injected electric current. In this we are using 593 nm ± Yellow-Orange
laser pointers, DPSS. The common wavelengths used are:
375 nm ± excitation of Hoechst stain, Calcium Blue, and other fluorescent dyes in fluorescence microscopy 405 nm ± InGaN blue-violet laser, in Blu-ray Disc and HD DVD drives 445 nm ± InGaN Deep blue laser multimode diode recently introduced (2010) for use in mercury free high brightness data projectors 473 nm ± Bright blue laser pointers, still very expensive, output of DPSS systems
4
485 nm ± excitation of GFP and other fluorescent dyes 510 nm - Green diodes recently (2010) developed by Nichia for laser projectors. 532 nm ± AlGaAs-pumped bright green laser pointers, frequency doubled 1064 nm Nd:YAG laser or (more commonly in laser pointers) Nd:YVO4 IR lasers (SHG) 593 nm ± Yellow-Orange laser pointers, DPSS 635 nm ± AlGaInP better red laser pointers, same power subjectively 5 times as bright as 670 nm one 640 nm ± High brightness red DPSS laser pointers 657 nm ± AlGaInP DVD drives, laser pointers 670 nm ± AlGaInP cheap red laser pointers 760 nm ± AlGaInP gas sensing: O2 785 nm ± GaAlAs Compact Disc drives 808 nm ± GaAlAs pumps in DPSS Nd:YAG lasers (e.g. in green laser pointers or as arrays in higher-powered lasers) 848 nm ± laser mice 980 nm ± InGaAs pump for optical amplifiers, for Yb:YAG DPSS lasers 1064 nm ± AlGaAs fiber-optic communication 1310 nm ± InGaAsP, InGaAsN fiber-optic communication 1480 nm ± InGaAsP pump for optical amplifiers 1512 nm ± InGaAsP gas sensing: NH3 1550 nm ± InGaAsP, InGaAsNSb fiber-optic communication 1625 nm ± InGaAsP fiber-optic communication, service channel 1654 nm ± InGaAsP gas sensing: CH4 1877 nm ± GaSbAs gas sensing: H2O 2004 nm ± GaSbAs gas sensing: CO2 2330 nm ± GaSbAs gas sensing: CO 2680 nm ± GaSbAs gas sensing: CO2
2.2.2 Photo Transistor:
A photodiode is a type of photodetector capable of converting light into
either current or voltage, depending upon the mode of operation.[1] The common, traditional solar cell used to generate electric solar power is a large area photodiode.
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Photodiodes are similar to regular semiconductor diodes except that they may be either exposed (to detect vacuum UV or X-rays) or packaged with a window or optical fiber connection to allow light to reach the sensitive part of the device. Many diodes designed for use specifically as a photodiode will also use a PIN junction rather than the typical p-n junction.
Material
Electromagnetic spectrum wavelength range (nm)
Silicon
190±1100
Germanium
400±1700
Indium gallium arsenide 800±2600
Lead(II) sulfide
<1000 ± 3500
Materials commonly used to produce photodiodes
2.2.3 Op-Amp LM 356:
The LM356 is a power amplifier designed for use in low voltage consumer applications. The gain is internally set to 20 to keep external part count low, but the addition of an external resistor and a capacitor between 1 and 8 will increase the gain to any value up tp 200. The inputs are grounded referenced while the output is automatically biased to one half the supply voltage. The quiescent power drain is only 24mW when operating from a 6V supply, making the LM356 ideal for battery operation.
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Connection Diagram
Applications of LM 356 are Am-FM radio amplifiers, Portable tape player amplifiers, Intercoms, TV sound system, Line drivers, Ultrasonic drivers, Small servo drivers, Power converters.
2.2.4 Monostable 555 timer:
The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation and oscillator applications. Depending on the manufacturer, the standard 555 package includes over 20 transistors, 2 diodes and 15 resistors on a silicon chip installed in an 8-pin mini dual-in-line package. In the monostable mode, the 555 timer acts as a ³one-shot´ pulse generator. The pulse begins when the 555 timer receives a signal at the trigger input that falls below a third of the voltage supply. The width of the output pulse is determined by the time constant of an RC network, which consists of a capacitor (C) and a resistor (R). Applications include timers, missing pulse detection, bouncefree switches, touch switches, frequency divider, capacitance measurement, pulse-width modulation (PWM) and so on.
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Pin diagram
Graph
2.2.5 Piezo Buzzer:
The piezo buzzer produces sound based on reverse of the piezoelectric effect. The generation of pressure variation or strain by the application of electric potential across a piezoelectric material is the underlying principle. These buzzers can be used alert a user of an event corresponding to a switching action, counter signal or sensor input. They are also used in alarm circuits. The buzzer produces a same noisy sound irrespective of the voltage variation applied to it. It consists of piezo crystals between two conductors. When a potential is applied across these crystals, they push on one conductor and pull on the other. This, push and pull action, results in a sound wave. Most buzzers produce sound in the range of 2 to 4 kHz.
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The Red lead is connected to the Input and the Black lead is connected to Ground.
2.2.6 Capacitor:
A capacitor 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 across the dielectric, causing positive charge to collect on one plate and negative charge on the other plate. Energy is stored in the electrostatic field. An ideal capacitor is characterized by a single constant value,capacitance, measured in farads. This is the ratio of the electric charge on each conductor to the potential difference between them. 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.
2.2.7 Resistor:
A linear resistor is a two-terminal, linear, passive electronic component that
implements electrical resistance as a circuit element. The current flowing through a resistor is in a direct proportion to the voltage across the resistor's terminals. Thus, the ratio of the voltage applied across resistor's terminals to the intensity of current flowing through the resistor is called resistance. This relation is represented with a well-known Ohm's law:
2.2.8 Diode:
A p±n junction is formed by joining P-type and N-type semiconductors together in very close contact. The term junction refers to the boundary interface where the two regions of the semiconductor meet. If they were constructed of two separate pieces this would introduce a grain boundary, so p±n junctions are created in a single crystal of semiconductor by doping, for example by ion implantation, diffusion of dopants, or by epitaxy
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2.2.9 Switch:
A switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another.
2.2.10 Battery:
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy.In this we are using a 9V battery.
2.2.11 Relay:
A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal. The first relays were used in long distance telegraph circuits, repeating the signal coming in from one circuit and re-transmitting it to another. Relays were used extensively in telephone exchanges and early computers to perform logical operations.
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CHAPTER 3 CIRCUIT DIAGRAM AND OPERATION OF CIRCUIT
3.1 Circuit diagram:
3.2 Operation of the circuit:
The transmitter circuit is nothing but a laser diode (LD1) driven by a 9V PP3 battery. The output of IC1 is regulated 5V as long as its input remains equal to or more than 7.5V, thus ensuring a constant drive current for the laser diode. The battery (Batt1) is connected to the circuit through switch S1. The laser diode (LD1) can be replaced with a laser pointer (torch) emitting red laser beam. The laser pointer itself can be used as a transmitter. The pointer has in-built series resistance, on/off switch and battery. The receiver circuit is basically a currentto-voltage converter built around IC LM356 (IC3). The output of IC3 is fed to the monostable built around 555 timer (IC4). The high output of the monostable drives the piezobuzzer to sound an audio alarm. The receiver section operates off 5V DC generated from another 9V battery and voltage regulator IC 7805 (IC2). The battery (Batt.2) is connected to the circuit through switch
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S2. When the laser light transmitted through LD1 falls on phototransistor T1, the output of the op-amp (IC3) at its pin 6 remains high. In this condition, the output of IC4 remains low and the buzzer does not sound. When the laser beam falling on phototransistor T1 is interrupted by someone, the output of op-amp IC3 goes low and IC3 produces a pulse. This pulse triggers monostable IC4 and its output goes high to sound the alarm for a time period of about R8xC8. Assemble the transmitter and receiver circuits on separate generalpurpose PCBs and enclose in suitable cabinets. Mount the transmitter and receiver units on opposite pillars of the entrance, aligning the two such that the laser beam from the transmitter directly falls on the phototransistor. Block the laser beam with your hand and measure the op-amp output. It should not be low. At pin 3 of IC4, we should get a positive-going pulse of one-second duration beginning with high-to-low edge of the trigger pulse appearing at pin 2 of IC4 or collector of transistor T2.
CHAPTER 4 CONSTRUCTION AND TESTING
4.1 Parts List:
R2, R3 R4 R5, R7 R6 R8 C3
1K,1/4W 22K,1/4W 10K,1/4W 47K,1/4W 1M,1/4W 10uF, 25V
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C4, C5, C7 C6 C8 D1 Battery Switches IC IC Relay Buzzer Transistor Photodiode(PD-1) Laser Diode(LD-1)
0.1uF 0.01uF 10uF, 16V IN4007 9V ON/OFF,SPST type 555 Timer OPAMP LM 356 6V Piezo buzzer BC548 BPX-65 Laser pointer
4.2 Construction steps:
Connect a phototransistor(T1) to the resistor R2 in series and connect it to the 3rd pin of the IC LM 356. Connect the resistor R3 to the 2nd pin of IC LM 356. Connect the 4th pin to the ground. Connect the resistor R4 to the 6th pin in series with the resistor R2. From the 6th pin connect the capacitor C6, resistor R5, R6, diode D1 to the base of the transistor T2. the resistor R5 is connected in parallel to diode D1. the collector is connected to the resistor R7. the
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capacitor C5 is connected to the pin 7 and 8 of the IC 356 and 555 timer. the collector of T2 is connected to the pin 2 of 555 timer. The pins 6,7 are connected to resistor R8 and capacitor C8. the pin 3 is connected to the piezo buzzer. The pins 4,6,7,8 of 555 timer and pin 7 of LM356 are connected to the collector of the T1. The pin 1 of 555 timer is connected to the ground and pin 5 is connected to C7 which in turn connected to the ground. The relay is connected to the 555 timer.
4.3 Testing:
Switch on the transistor circuit. Align the transmitter and receiver circuit so that the laser beam falls on the photodiode. We can use a small transmitter receiver distance, even a few feet, for the purpose. If necessary, change the value of one or more resistors(R5,R6,R7) to get a signal peak magnitude of 2 to 3 V at opamp output. Block the laser radiation with our hand and again measure the opamp output. It should be near zero volt. If we have the services of an oscilloscope, observe the pulse waveforms appearning at pin-8 of IC-1 and pin-6 of IC-3. At pin-8 of IC-4, we would see a HIGH-to-LOW transition every time we block the laser beam. We can observe change in the pitch of the audio beep by changing the frequency of the signal on the transmitter card.
CHAPTER 5 SPECIFICATION AND APPLICATION
5.1 Specification:
y y PCB 4x4 593 nm ± Yellow-Red laser pointers
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y y
y
Battery 9V Photodiode BPX-65 or equivalent PiezoBuzzer
5.2 Advantages:
Simplicity of installation. The effective ability to be used indoors and outdoors. It could be used as an effective alarm for the house/company boundaries. It uses the normal power outlets and telephone jacks in case it used indoors. It could be expensive and could be difficult for many customers to afford it.
5.3 Disadvantages:
The disadvantage of laser beamsystem is that it may get activated by a cat walking on the wall or a large bird sitting on the wall. They are more expensive compared to simple security alarm systems.
5.4 Applications:
Can be used as home security system
Can be used in Museums, Banks, Offices for safe guard many valuable things.
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CHAPTER 6 CONCLUSION
The Laser Based Intruder Alarm was built to our satisfaction. This project is about how to prevent theft in homes, offices, banks, museums etc, This project can be implemented by both wired and wireless technologies. Another application of this instrument is as an "ANTITHEFT SYSTEM", that means to protect vehicles from kidnapping. In short I am sure that this device is highly useful to mankind especially present scenario.
References: http://www.ieee.org/searchresults/index.html?cx=006539740418318249752%3Af2h38l7gvis&c
of=FORID%3A11&qp=&ie=UTF-8&oe=UTF8&q=laser+alarm+systems&siteurl=www.ieee.org%252Findex.html
http://en.wikipedia.org/wiki/Main_Page http://books.google.com/books?id=Dx3Mdx_oDHsC&printsec=frontcover&source=gbs_ge_sum
mary_r&cad=0#v=onepage&q&f=false
http://www.scribd.com
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INTRODUCTION
1.1 AIM OF THE PROJECT:
A alarm is a type of security equipment that can be used to safeguard homes and
property. If we love our home then buying burglar alarm should be our first priority when moving to a new home. Burglar crimes are continually rising with each passing day. Many have lost their homes and families through violent burglaries in many countries today. Some have lost what they considered precious and valuable to them. Things such as jewelry, vehicles, and clothes are huge investments to many.
During the olden days a watchman would be hired to take care of property and offer needed security in the home. Some homes also had fierce dogs that would be let out only at night. The two were supposed to provide security to our belongings even in the absence of the owner. However, hiring a watchman was not an effective method since most of them would be killed in the line of duty. Sometimes dogs would attack even visitors while some watchmen looted property. This led to the development of alarm equipments.
1.2 ABOUT THE CICUIT:
The circuit is divided into two parts i.e. the transmitter and the receiver part
Transmitter point:
The tranmitter circuit is othing but a laser diode driven by a battery connected to the diode through a series resistance R1. In order to ensure that the current through the diode remains constant irrespective of drop in battery voltage, a 3-terminal voltage regulator VR-1 has bee used. This regulator produces a constant 5V output as long as input remains equal to or more
1
than 7.5V thus ensuring a constant drive current for the laser diode. The drive current in this case would be(3500/47) mA. The laser diode here can be the one typically used in laser pointers emitting in red. This would be more economical than buying one. If the experiment so desires, we can use the laser pointer itself as a complete transmitter circuit. The pointer has in-built suitable series resistance and an ON/OFF switch and a battery. The given circuit would help when we want to go a step further and want to use infrared laser diode so as to get an invisible laser beam, which would be a requirement in any intruder alarm system, I recommend the use of laser pointer for the purpose of learning and demonstration.
Receiver part:
The receiver part basically comprises of a current to voltage converter section configured around IC1(OP AMP 356) feeding a positive edge triggered monoshot configuration buit around IC2(555 timer). The output of the monoshot feeds a buzzer that gives an audio beep during the time it get a high input from the timer IC 555. The receiver section operates from +5V DC generated from another 9V battery and 3 terminal regulator VR2. The battery can be connected to the circuit through switch SW2 The current-to-voltage converter section converts the photocurrent produced by the photodiode PD1 as a result of laser light falling on it into an equivalent vltage across resistor R2. This voltage gets amplified bya factor of 23 in the non-inverting amplifier provided by an OP-AMP and resistors R3,R4. So, when the laser light is falling on the photodiode, the opamp output is same DC voltage, The component values have been so chosen as to produce about 5V DC for a laser power of 0.5mW, typical of a laser pointer. Otherwise the amplifier gain can be adjusted to produce 5VDC.
1.3 ADVANTAGES OVER COMMERCIAL SECURITY SYSTEMS:
There are dozens of different security systems on the market that utilize lasers and can effectively protect everything from small apartments and businesses to large areas of property. Most home laser security systems consist of two parts: a basic alarm unit and an
2
infrared motion detector. Laser security systems of the past used to rely on connections wired to a keypad, requiring the customer to use special codes to arm and disarm the system. Since the majority of laser security systems are now wireless, the units can be turned on or off with a wireless remote or, in some models, by touch tone phone from anywhere in the world.
The basic sensing component of a modern laser security system is an infrared motion detector. An infrared motion detector works by using beams of infrared light to detect changes in heat which is absent in most of the commercial security systems. Laser alarm systems provides the state of the art features and benefits of a conventional monitored alarm system. Laser alarm systems is an advanced and effective security system that does the job right. Laser alarm systems can be activated in seconds without programming, installation, in-home sales people and technicians; and with no hassle, mess, or waiting. There are no hidden costs, no on-going service calls and costs, and Rapid Response Monitoring Service provides the most technologically advanced monitoring service available. All at a fraction of the cost of other major brands. Laser alarm systems is perfect for homes, condos, apartments, small offices, and retail stores.
Laser security systems have many advantages. They are simple to install and can be used effectively inside or outside a home. The systems can be used as a highly effective perimeter alarm for property boundaries or even for pools, where customers can have the lasers set to detect when small children come within a set number of feet from the edge of the water. Indoors, the sensors utilize normal power outlets and telephone jacks; outdoors, the sensors can be hidden beneath plants and bushes and will not harm lawns or other vegetation. However, laser security systems can be prohibitively expensive. While some security system plans allow for customers to target one room, plans that protect large amounts of land or an entire house will cost much more and can be difficult for many customers to afford .
3
CHAPTER 2 BLOCK DIAGRAM AND EXPLANATION
2.1 BLOCK DIAGRAM:
Block diagram
2.2 BLOCK DIAGRAM EXPLANATION 2.2.1 Laser Diode/Pointer:
The laser diode is a laser where the active medium is a semiconductor similar to that found in a light-emitting diode. The most common type of laser diode is formed from a p-n junction and powered by injected electric current. In this we are using 593 nm ± Yellow-Orange
laser pointers, DPSS. The common wavelengths used are:
375 nm ± excitation of Hoechst stain, Calcium Blue, and other fluorescent dyes in fluorescence microscopy 405 nm ± InGaN blue-violet laser, in Blu-ray Disc and HD DVD drives 445 nm ± InGaN Deep blue laser multimode diode recently introduced (2010) for use in mercury free high brightness data projectors 473 nm ± Bright blue laser pointers, still very expensive, output of DPSS systems
4
485 nm ± excitation of GFP and other fluorescent dyes 510 nm - Green diodes recently (2010) developed by Nichia for laser projectors. 532 nm ± AlGaAs-pumped bright green laser pointers, frequency doubled 1064 nm Nd:YAG laser or (more commonly in laser pointers) Nd:YVO4 IR lasers (SHG) 593 nm ± Yellow-Orange laser pointers, DPSS 635 nm ± AlGaInP better red laser pointers, same power subjectively 5 times as bright as 670 nm one 640 nm ± High brightness red DPSS laser pointers 657 nm ± AlGaInP DVD drives, laser pointers 670 nm ± AlGaInP cheap red laser pointers 760 nm ± AlGaInP gas sensing: O2 785 nm ± GaAlAs Compact Disc drives 808 nm ± GaAlAs pumps in DPSS Nd:YAG lasers (e.g. in green laser pointers or as arrays in higher-powered lasers) 848 nm ± laser mice 980 nm ± InGaAs pump for optical amplifiers, for Yb:YAG DPSS lasers 1064 nm ± AlGaAs fiber-optic communication 1310 nm ± InGaAsP, InGaAsN fiber-optic communication 1480 nm ± InGaAsP pump for optical amplifiers 1512 nm ± InGaAsP gas sensing: NH3 1550 nm ± InGaAsP, InGaAsNSb fiber-optic communication 1625 nm ± InGaAsP fiber-optic communication, service channel 1654 nm ± InGaAsP gas sensing: CH4 1877 nm ± GaSbAs gas sensing: H2O 2004 nm ± GaSbAs gas sensing: CO2 2330 nm ± GaSbAs gas sensing: CO 2680 nm ± GaSbAs gas sensing: CO2
2.2.2 Photo Transistor:
A photodiode is a type of photodetector capable of converting light into
either current or voltage, depending upon the mode of operation.[1] The common, traditional solar cell used to generate electric solar power is a large area photodiode.
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Photodiodes are similar to regular semiconductor diodes except that they may be either exposed (to detect vacuum UV or X-rays) or packaged with a window or optical fiber connection to allow light to reach the sensitive part of the device. Many diodes designed for use specifically as a photodiode will also use a PIN junction rather than the typical p-n junction.
Material
Electromagnetic spectrum wavelength range (nm)
Silicon
190±1100
Germanium
400±1700
Indium gallium arsenide 800±2600
Lead(II) sulfide
<1000 ± 3500
Materials commonly used to produce photodiodes
2.2.3 Op-Amp LM 356:
The LM356 is a power amplifier designed for use in low voltage consumer applications. The gain is internally set to 20 to keep external part count low, but the addition of an external resistor and a capacitor between 1 and 8 will increase the gain to any value up tp 200. The inputs are grounded referenced while the output is automatically biased to one half the supply voltage. The quiescent power drain is only 24mW when operating from a 6V supply, making the LM356 ideal for battery operation.
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Connection Diagram
Applications of LM 356 are Am-FM radio amplifiers, Portable tape player amplifiers, Intercoms, TV sound system, Line drivers, Ultrasonic drivers, Small servo drivers, Power converters.
2.2.4 Monostable 555 timer:
The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation and oscillator applications. Depending on the manufacturer, the standard 555 package includes over 20 transistors, 2 diodes and 15 resistors on a silicon chip installed in an 8-pin mini dual-in-line package. In the monostable mode, the 555 timer acts as a ³one-shot´ pulse generator. The pulse begins when the 555 timer receives a signal at the trigger input that falls below a third of the voltage supply. The width of the output pulse is determined by the time constant of an RC network, which consists of a capacitor (C) and a resistor (R). Applications include timers, missing pulse detection, bouncefree switches, touch switches, frequency divider, capacitance measurement, pulse-width modulation (PWM) and so on.
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Pin diagram
Graph
2.2.5 Piezo Buzzer:
The piezo buzzer produces sound based on reverse of the piezoelectric effect. The generation of pressure variation or strain by the application of electric potential across a piezoelectric material is the underlying principle. These buzzers can be used alert a user of an event corresponding to a switching action, counter signal or sensor input. They are also used in alarm circuits. The buzzer produces a same noisy sound irrespective of the voltage variation applied to it. It consists of piezo crystals between two conductors. When a potential is applied across these crystals, they push on one conductor and pull on the other. This, push and pull action, results in a sound wave. Most buzzers produce sound in the range of 2 to 4 kHz.
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The Red lead is connected to the Input and the Black lead is connected to Ground.
2.2.6 Capacitor:
A capacitor 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 across the dielectric, causing positive charge to collect on one plate and negative charge on the other plate. Energy is stored in the electrostatic field. An ideal capacitor is characterized by a single constant value,capacitance, measured in farads. This is the ratio of the electric charge on each conductor to the potential difference between them. 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.
2.2.7 Resistor:
A linear resistor is a two-terminal, linear, passive electronic component that
implements electrical resistance as a circuit element. The current flowing through a resistor is in a direct proportion to the voltage across the resistor's terminals. Thus, the ratio of the voltage applied across resistor's terminals to the intensity of current flowing through the resistor is called resistance. This relation is represented with a well-known Ohm's law:
2.2.8 Diode:
A p±n junction is formed by joining P-type and N-type semiconductors together in very close contact. The term junction refers to the boundary interface where the two regions of the semiconductor meet. If they were constructed of two separate pieces this would introduce a grain boundary, so p±n junctions are created in a single crystal of semiconductor by doping, for example by ion implantation, diffusion of dopants, or by epitaxy
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2.2.9 Switch:
A switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another.
2.2.10 Battery:
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy.In this we are using a 9V battery.
2.2.11 Relay:
A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal. The first relays were used in long distance telegraph circuits, repeating the signal coming in from one circuit and re-transmitting it to another. Relays were used extensively in telephone exchanges and early computers to perform logical operations.
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CHAPTER 3 CIRCUIT DIAGRAM AND OPERATION OF CIRCUIT
3.1 Circuit diagram:
3.2 Operation of the circuit:
The transmitter circuit is nothing but a laser diode (LD1) driven by a 9V PP3 battery. The output of IC1 is regulated 5V as long as its input remains equal to or more than 7.5V, thus ensuring a constant drive current for the laser diode. The battery (Batt1) is connected to the circuit through switch S1. The laser diode (LD1) can be replaced with a laser pointer (torch) emitting red laser beam. The laser pointer itself can be used as a transmitter. The pointer has in-built series resistance, on/off switch and battery. The receiver circuit is basically a currentto-voltage converter built around IC LM356 (IC3). The output of IC3 is fed to the monostable built around 555 timer (IC4). The high output of the monostable drives the piezobuzzer to sound an audio alarm. The receiver section operates off 5V DC generated from another 9V battery and voltage regulator IC 7805 (IC2). The battery (Batt.2) is connected to the circuit through switch
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S2. When the laser light transmitted through LD1 falls on phototransistor T1, the output of the op-amp (IC3) at its pin 6 remains high. In this condition, the output of IC4 remains low and the buzzer does not sound. When the laser beam falling on phototransistor T1 is interrupted by someone, the output of op-amp IC3 goes low and IC3 produces a pulse. This pulse triggers monostable IC4 and its output goes high to sound the alarm for a time period of about R8xC8. Assemble the transmitter and receiver circuits on separate generalpurpose PCBs and enclose in suitable cabinets. Mount the transmitter and receiver units on opposite pillars of the entrance, aligning the two such that the laser beam from the transmitter directly falls on the phototransistor. Block the laser beam with your hand and measure the op-amp output. It should not be low. At pin 3 of IC4, we should get a positive-going pulse of one-second duration beginning with high-to-low edge of the trigger pulse appearing at pin 2 of IC4 or collector of transistor T2.
CHAPTER 4 CONSTRUCTION AND TESTING
4.1 Parts List:
R2, R3 R4 R5, R7 R6 R8 C3
1K,1/4W 22K,1/4W 10K,1/4W 47K,1/4W 1M,1/4W 10uF, 25V
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C4, C5, C7 C6 C8 D1 Battery Switches IC IC Relay Buzzer Transistor Photodiode(PD-1) Laser Diode(LD-1)
0.1uF 0.01uF 10uF, 16V IN4007 9V ON/OFF,SPST type 555 Timer OPAMP LM 356 6V Piezo buzzer BC548 BPX-65 Laser pointer
4.2 Construction steps:
Connect a phototransistor(T1) to the resistor R2 in series and connect it to the 3rd pin of the IC LM 356. Connect the resistor R3 to the 2nd pin of IC LM 356. Connect the 4th pin to the ground. Connect the resistor R4 to the 6th pin in series with the resistor R2. From the 6th pin connect the capacitor C6, resistor R5, R6, diode D1 to the base of the transistor T2. the resistor R5 is connected in parallel to diode D1. the collector is connected to the resistor R7. the
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capacitor C5 is connected to the pin 7 and 8 of the IC 356 and 555 timer. the collector of T2 is connected to the pin 2 of 555 timer. The pins 6,7 are connected to resistor R8 and capacitor C8. the pin 3 is connected to the piezo buzzer. The pins 4,6,7,8 of 555 timer and pin 7 of LM356 are connected to the collector of the T1. The pin 1 of 555 timer is connected to the ground and pin 5 is connected to C7 which in turn connected to the ground. The relay is connected to the 555 timer.
4.3 Testing:
Switch on the transistor circuit. Align the transmitter and receiver circuit so that the laser beam falls on the photodiode. We can use a small transmitter receiver distance, even a few feet, for the purpose. If necessary, change the value of one or more resistors(R5,R6,R7) to get a signal peak magnitude of 2 to 3 V at opamp output. Block the laser radiation with our hand and again measure the opamp output. It should be near zero volt. If we have the services of an oscilloscope, observe the pulse waveforms appearning at pin-8 of IC-1 and pin-6 of IC-3. At pin-8 of IC-4, we would see a HIGH-to-LOW transition every time we block the laser beam. We can observe change in the pitch of the audio beep by changing the frequency of the signal on the transmitter card.
CHAPTER 5 SPECIFICATION AND APPLICATION
5.1 Specification:
y y PCB 4x4 593 nm ± Yellow-Red laser pointers
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y y
y
Battery 9V Photodiode BPX-65 or equivalent PiezoBuzzer
5.2 Advantages:
Simplicity of installation. The effective ability to be used indoors and outdoors. It could be used as an effective alarm for the house/company boundaries. It uses the normal power outlets and telephone jacks in case it used indoors. It could be expensive and could be difficult for many customers to afford it.
5.3 Disadvantages:
The disadvantage of laser beamsystem is that it may get activated by a cat walking on the wall or a large bird sitting on the wall. They are more expensive compared to simple security alarm systems.
5.4 Applications:
Can be used as home security system
Can be used in Museums, Banks, Offices for safe guard many valuable things.
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CHAPTER 6 CONCLUSION
The Laser Based Intruder Alarm was built to our satisfaction. This project is about how to prevent theft in homes, offices, banks, museums etc, This project can be implemented by both wired and wireless technologies. Another application of this instrument is as an "ANTITHEFT SYSTEM", that means to protect vehicles from kidnapping. In short I am sure that this device is highly useful to mankind especially present scenario.
References: http://www.ieee.org/searchresults/index.html?cx=006539740418318249752%3Af2h38l7gvis&c
of=FORID%3A11&qp=&ie=UTF-8&oe=UTF8&q=laser+alarm+systems&siteurl=www.ieee.org%252Findex.html
http://en.wikipedia.org/wiki/Main_Page http://books.google.com/books?id=Dx3Mdx_oDHsC&printsec=frontcover&source=gbs_ge_sum
mary_r&cad=0#v=onepage&q&f=false
http://www.scribd.com
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