61113070 Laser Based Intruder Alarm Ppt

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P During the olden days a watchman would be
hired to take care oI property and oIIer
needed security in the home. Some homes
also had Iierce dogs that would be let out
only at night. The two were supposed to
provide security to our belongings even in
the absence oI the owner. However, hiring a
watchman was not an eIIective method since
most oI them would be killed in the line oI
duty. Sometimes dogs would attack even
visitors while some watchmen looted
property.
During Ihe c|cen ccy: where Ihere were nc :ecuriIy
:y:Iem: hcu:e: were Leing rcicec Ly Ihe Ihieve:
alarm is a type oI security
equipment that can be used to
saIeguard homes and property. II
we love our home then buying
burglar alarm should be our Iirst
priority when moving to a new
home. Burglar crimes are
continually rising with each
passing day. Many have lost their
homes and Iamilies 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. This
led to the development oI the
alarm equipment.
/ìovì ìnc .i·.viì
P The circuit is divided into two parts i.e. the
transmitter and the receiver.
P The transmitter circuit is nothing but a laser
diode driven by a battery connected to the diode
P In order to ensure that the current remains
constant in the diode a 5V or 7.5V is applied to
the diode.
P The laser diode here can be the one typically
used in laser pointers emitting in red. This
would be more economical than buying one.
P n inIrared diode can also be used Ior invisible
laser beam.
P The pointer has in-built suitable series
resistance and an ON/OFF switch and a battery.
P The drive current in this would be 3500/47m.
P The receiver part consists oI a current to
voltage converter section which converts the
photocurrent produced by the photodiode as a
result oI laser light Ialling.
P When the laser light Ialls on the photodiode, the
opamp output is same as Dc voltage
±ìo.[ viv¡·vn
P ,807 /4/0 543907 The laser diode is a laser
where the active medium is a semiconductor
similar to that Iound in a light-emitting diode. The
most common type oI laser diode is Iormed Irom
a p-n junction and powered by injected electric
current. In this we are using 32 Yellow-
Orange laser pointers.
P !hoto transistor photodiode is a type
oI photo detector capable oI
converting light into either current or voltage,
depending upon the mode oI operation. The
common, traditional solar cell used to generate
electric solar power is a large area photodiode.
P Op-mp LM 356 The LM356 is a power
ampliIier designed Ior use in low voltage
consumer applications. The gain is internally
set to 20 to keep external part count low, but the
addition oI an external resistor and a capacitor
between 1 and 8 will increase the gain to any
value up tp 200. The inputs are grounded
reIerenced while the output is automatically
biased to one halI the supply voltage. The
quiescent power drain is only 24mW when
operating Irom a 6V supply, making the LM356
ideal Ior battery operation.
P 555 Timer The 555 timer IC is an integrated
circuit (chip) used in a variety oI timer, pulse
generation and oscillator applications. It
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 'one-
shot¨ pulse generator. The pulse begins when
the 555 timer receives a signal at the trigger
input that Ialls below a third oI the voltage
supply. The width oI the output pulse is
determined by the time constant oI an RC
network, which consists oI a capacitor (C) and
a resistor (R).
P !iezo buzzer The piezo buzzer produces sound
based on reverse oI the piezoelectric eIIect. The
generation oI pressure variation or strain by the
application oI electric potential across a
piezoelectric material is the underlying
principle. These buzzers can be used alert a user
oI an event corresponding to a switching action,
counter signal or sensor input. They are also
used in alarm circuits.
P Capacitor capacitor is a passive electronic
component consisting oI a pair
oI conductors separated by
a dielectric (insulator). When there is a potential
diIIerence (voltage) across the conductors, a
static electric Iield develops across the
dielectric causing positive charge to collect on
P one plate and negative charge on the other plate
P Resistor linear resistor is a two-terminal,
linear, passive electronic component that
implements electrical resistance as a circuit
element
P Diode pn junction is Iormed by joining !-
type and N-type semiconductors together in
very close contact.
P Switch It`s an electrical component that break
an electrical circuit.
P ,9907 It is used to convert chemical energy
to electrical energy.
P Relay It is as an electrically operated switch.
It uses an electromagnetic to operate a
switching mechanism mechanically
P It is used to control a circuit by a low power
signal
P Relays are used extensively in telephone
exchange and early computers to perIorm
logical operations.
(i·.viì viv¡·vn vnv o¡c·vìion
P The transmitter circuit is nothing but a laser
diode (LD1) driven by a 9V !!3 battery. The
output oI IC1 is regulated 5V as long as its
input remains equal to or more than 7.5V, thus
ensuring a constant drive current Ior 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 itselI can be used as a transmitter. The
pointer has in-built series resistance, on/oII
switch and battery. The receiver circuit is
basically a current-to-voltage converter built
around IC LM356 (IC3). The output oI IC3 is
Ied to the monostable built around 555 timer
(IC4). The high output oI the monostable drives
the piezobuzzer to sound an audio alarm. The
receiver section operates oII 5V DC generated Irom
another 9V battery and voltage regulator IC 7805
(IC2). The battery (Batt.2) is connected to the
circuit through switch S2. When the laser light
transmitted through LD1 Ialls on phototransistor
T1, the output oI the op-amp (IC3) at its pin 6
remains high. In this condition, the output oI IC4
remains low and the buzzer does not sound. When
the laser beam Ialling on phototransistor T1 is
interrupted by someone, the output oI op-amp
IC3 goes low and IC3 produces a pulse. This
pulse triggers monostable IC4 and its output
goes high to sound the alarm Ior a time period
oI about
R8xc8. ssemble the transmitter and receiver
circuits on separate generalpurpose !CBs and
enclose in suitable cabinets. Mount the
transmitter and receiver units on opposite
pillars oI the entrance, aligning the two such
that the laser beam Irom the transmitter directly
Ialls on the phototransistor. Block the laser
beam with your hand and measure the op-amp
output. It should not be low. t pin 3 oI IC4, we
should get a positive-going pulse oI one-second
duration beginning with high-to-low edge oI the
trigger pulse appearing at pin 2 oI IC4 or
collector oI transistor T2.
Ic.ìin¡
P Switch on the transistor circuit. lign the
transmitter and receiver circuit so that the
laser beam Ialls on the photodiode. We
can use a small transmitter receiver
distance, even a Iew Ieet, Ior the purpose.
P II necessary, change the value oI one or
more resistors(R5,R6,R7) to get a signal
peak magnitude oI 2 to 3 V at opamp
output.
P Block the laser radiation with our hand
and again measure the opampoutput. It
should be near zero.
P Block the laser radiation with our hand and
again measure the opamp output. It should be
near zero volt.
P II we have the services oI an oscilloscope,
observe the pulse waveIorms appearning at pin-
8 oI IC-1 and pin-6 oI IC-3. t pin-8 oI IC-4,
we would see a HIGH-to-LOW transition every
time we block the laser beam.
P We can observe change in the pitch oI the audio
beep by changing the Irequency oI the signal on
the transmitter card.
/v.vnìv¡c.
P Simplicity oI installation.
P The eIIective ability to be used indoors
and outdoors.
P It could be used as an eIIective alarm Ior
the house/company boundaries.
P It uses the normal power outlets and
telephone jacks in case it used indoors.
Ii.vv.vnìv¡c.
The disadvantage oI laser
beam system 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.
/¡¡ìi.vìion. Can be used as
home security system
Can be used in Museums,
Banks, OIIices Ior saIe guard
many valuable things
(on.ìv.ion
P The Laser Based Intruder larm was built to
our satisIaction. This project is about how to
prevent theIt in homes, oIIices, banks,
museums etc, This project can be implemented
by both wired and wireless technologies.
nother application oI this instrument is as an
"NTI-THEFT SYSTEM", that means to
protect vehicles Irom kidnapping. In short I am
sure that this device is highly useIul to mankind
especially present scenario.

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