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SDCCL PUBLIC SCHOOLSDCCL PUBLIC SCHOOL
PHYSICS PROJECTPHYSICS PROJECT
•Topic: Laser Security Alarm System.
•Submitted To : Shweta Mishra.
•Submitted By : Vishwa Rana.
•Class : 12th- A.
•Roll No. : 14.
•Date of Submitted :
This is to certify that Miss Vishwa Rana of class 12th-A
has successfully completed this physics project
entitled " Laser Security Alarm System " under my
guidance and supervision in the academic year 2015-
2016,Miss Shweta Mishra.
Principal signature Teacher Signature
First of all , I heartily thank my physics Teacher , Miss
Shweta Mishra for her incomparable efforts, support
and constant cooperation indeed towards me in the
completion of this project.He has also been the vital
source of encouragement for me through the working
of this project. Finally I would also grateful to my
friends and parents who devoted their auspicious
time in completion of this project.
Thank You Vishwa Rana.
"My project provides complete information on the
topic"Laser Security Alarm System " and maximum
efforts have been taken to make the project more
comprehensive and lucid to understand. My project
covers a variety of sub topics like It's working, setup,
uses in life and different aspects of Laser Security
Alarm System . One may notice a perceptible change
in written in an easy dialogue style engaging the
readers constantly and included with more
informatics comments. I assure you to go through
this project thoroughly to know a bit more and facts
about Laser Security Alarm System .
• Components / Materisl Required.
• Circuit Diagram.
• Experimental Setup.
• Uses Of Laser Security Alarm System .
• Advantages Of Laser Security Alarm
Components / MaterialComponents / Material
Required.Required.1)1)BreadboardBreadboard:: A breadboard also known as protoboard is a type of solderless
electronic circuit building.You can build a electronic circuit on a breadboard without
any soldering ! Best of all it is reusable.
2)LDR:2)LDR: A photoresistor or light-dependent resistor (LDR) or photocell is a light-
controlled variable resistor. The resistance of a photoresistor decreases with
increasing incident light intensity; in other words, it exhibits photoconductivity
4) NPN Transistor4) NPN Transistor : NPN is one of the two types of bipolar transistors, consisting
of a layer of P-doped semiconductor (the "base") between two N-doped layers. A
small current entering the base is amplified to produce a large collector and emitter
3)Resistor3)Resistor :A resistor is an electrical component that limits or regulates the flow of
electrical current in an electronic circuit. Resistors can also be used to provide a
specific voltage for an active device such as a transistor.
5)Laser Pointer5)Laser Pointer:: A laser pointer or laser pen is a small handheld device with a power
source (usually a battery) and a laser diode emitting a very narrow coherent low-
powered laser beam of visible light, intended to be used to highlight something of
interest by illuminating it with a small bright spot of colored light.
6)LED6)LED :: A light-emitting diode (LED) is a semiconductor device that emits visible light
when an electric current passes through it.
7) Battery7) Battery ::A container consisting of one or more cells, in which chemical energy is
converted into electricity and used as a source of power.
8) Wire8) Wire :: Metal drawn out into the form of a thin flexible thread or rod. That connects
different components in a circuit .
99)Buzzer)Buzzer : An electrical device that makes a buzzing noise and is used for signalling.
10)Battery Clip:10)Battery Clip: It is the thing with two studs on it, it provides an electrical
connection to the battery.
11)11)CAPACITOR :CAPACITOR : A device used to store an electric charge, consisting of one or more
pairs of conductors separated by an insulator.
Security is a most important factor today.Technology develops day by day in
the world.The crime gang also improves their technology toperform their
So technology of securityshould be modern with time to protect the crime
works.We decide to make a security project as our project. Inthis project
we have used laser light to cover a large area.
We know laser light goes through long distancewithout scattering effect. It’s
also visible only at sourceand incident point, otherwise invisible.
These two properties help us to build up a modern security system,which may
name as “laser security”.
When any personor object crossover the laser line the security alarm
willringing and also the focus light will “on” to focus the
entrance of unauthorized person. We can make asecurity boundary of single
laser light by using mirror at every corner for reflection.
Circuit DiagramCircuit Diagram
Experimental SetupExperimental Setup
1) Connect a photocell to a 5K resistor. This will pick up the laser light
and enable the alarm.
2) Use a 2N7000 transistor to link the resistor, a 1uF 63v capacitor, a
5v siren and a 9v battery clip. The attached schematic should
demonstrate how the parts come together. Use an breadboard to
hold them in place and make sure the board is small enough to fit
into a project box. Do not connect the battery yet.
3) Use tape, glue, or strips of velcro to mount the two project boxes
on either side of the door you wish to protect.
4) Connect a 9v battery to the first project box and replace it in the
exact position is was in.
5) Turn the laser on with the toggle switch and make sure it lines up
perfectly with the photo cell. The alarm is now activated. If
anything breaks the beam, the siren will go off.
1) This circuit is based on LDR (Light Depended Resistor), a variable resistor in which the
resistance varies according to the light intensity falling on it.
2) The LDR and resistor R1 forms a potential divider network, which is the main part of
our security alarm circuit.
3) We have already discussed about how transistor acts as a switch, the same principle is
4) The voltage drop across the LDR is used to drive the transistor switch. When the
voltage drop is above cut in voltage (0.6V), the transistor is turned ON.
5) LDR has low resistance (mΩ range) in the presence of light and high resistance (MΩ
range) in the absence of light.
6) In our security alarm, a LASER light is allowed to fall on the LDR continuously using 3
mirrors (see the project arrangement figure).
7) Light from other sources should not be allowed to fall on the LDR, so place the LDR in
a box with a single hole to pass LASER.
8) In this situation, the resistance offered by LDR is too low, since the LASER light is
continuously allowed to fall on the LDR surface.
9) Thus the voltage drop across the LDR is also low [V=IR (Ohm’s law)] which is
insufficient to turn ON the transistor, so the transistor remains in OFF state.
10) When a person (eg: thief) makes a block to the continuous flow of LASER beam, then
the light falling on the LDR gets blocked. Thus its resistance increases to a high value
in the order of MΩ range (According to Ohm’s law V=IR).
11) While resistance increases the voltage drop also increases, when this voltage drop
exceeds the cut in voltage of the silicon NPN transistor (2N7000), it will turn ON.
12) Then current from Vcc starts flowing to ground via the buzzer and transistor, which
makes the beep sound.
13) The beep sound from the security alarm gives the indication of some security failures.
Uses Of Laser Security Alarm System
1) Laser Security System Locks Working1) Laser Security System Locks Working : Laser door alarm is based on
the interruption of Laser beam. The laser pointer is used as the source of
• If somebody tries to break the laser path, then an alarm will be generated in
a few seconds. Normally laser door alarm circuit will have two sections.
• First one, laser transmitter is a laser pointer readily available. This is
powered with 3 volt DC supply and fixed on one side of the door frame.
• The receiver will have a Photo transistor at the front end. We use 2N7000
NPN Darlington photo transistor as a laser sensor.
• Here IC1 is used as a voltage comparator with its inverting input tied to a
potential divider R2-R3. We use the inverting input to keep at half supply
2) Laser System2) Laser System : Laser technology products will calculate distance by
measuring the time of flight of very short pulses of infrared light. It is
different from the traditional surveying instrument method of measuring
phase shifts by comparing the incoming wavelength with the phase of the
outgoing light pulse.
• Solid objects will reflect back a certain percentage of the emitted light
energy. It only needs to be a small percentage for our sensitive detector to
pick it. We can measure the time it takes for a laser pulse to travel to the
target and back with a reflection. By knowing the constant speed of light
we can calculate the distance traveled. It calculate accurate area of house
and protects it from thiefs .
3) Theft Detection by Laser Sytem3) Theft Detection by Laser Sytem : It can be designed as a simple
electronic project for demonstration in science exhibitions. It can also be made
as a mini or major project for electrical or electronic students.
• When making this laser security system one can know all about laser beams and
their installation. While preparing a laser security system, we need to
concentrate on the microcontroller program and installed with the laser beam
• When using traditional photo resistors for preparing security systems one has
to consider the natural light phenomena. Laser are strong in beam width and can
be focused on the perfect target.
• By using laser security system one can
be safe in the case of harmful effects
to the body. As the beam width used in
The laser security systems are not strong
beam widths. Which are used in the
4)Other Uses Of Laser Security Systems4)Other Uses Of Laser Security Systems : The Laser security systems
are high tech innovations that have gained popularity in home and office
security systems. These are used to be expensive solutions for security
needs. Depending on cost and fast technological advancements laser
security systems becoming more adoptable.
• Home security is rapidly growing field and there are new &
improved burglar alarms popping up everyday.
• With rapid advancement of technology the filled is turning out
to be an area full of scope and new changes can be made to make
it’s more efficient.
• It has years to come, because security is of prime importance to
one and all.