Introduction:
Have you ever thought about
implementing your own home security alarm systems? It’s one of the simplest and
interesting circuits for electronic beginners. Our new home security equipment
uses a LDR (Light Depended Resistor) to detect security problems. Theft attempt
and other security threats can be controlled by using this simple circuit to
improve your security system.
To
implement this alarm system for home, you have to provide an optical path (with
LASER beams) around your home. The LASER path is made possible with one LASER
torch and 3 mirror arrangements which encloses the whole area. Please refer the
project arrangement section below to make this optical (light) path. Security
is a most important factor today. Technology develops day by day in the world.
The crime gang also improves their technology to
perform
their operation. So technology of security should be modern with time to
protect the crime works.
We
decide to make a security project as our project. In this project we have used
laser light to cover a largearea. We know laser light goes through long
distance without scattering effect. It’s also visible only at source and
incident point, otherwise invisible. These two properties help us to build up a
modern security system, which may name as “laser security”. When any person or
object crossover the laser line the security alarm will
ringing
and also the focus light will “on” to focus the entrance of unauthorized
person. We can make a security boundary of single laser light by using mirrorat
every corner for reflection.
Block
diagram
Actual working
This circuit uses a
popular timer I.C which is 555. the output of
ic555 goes high-1 when the trigger pin 2 is at lower than 1/3 level of
the supply voltage, conversely the output goes low-0 when it is above 1/3. So
small change in voltage of pin 2 is enough to change the output state of pin 3
from 1 to 0 and 0 to 1. The output has only two states high and low and cannot
remain in any intermediate stage. It is power by 9V battery for portable use.
The circuit is economical in power consumption. Pin 4& 8 is connected to
the positive supply and pin 1 is grounded.
To detect the present
robber we have used LDR and a source of light.
LDR is a special type of
resistance whose value depends on the brightness of the light, which is falling
on it. It has a resistance of about 1 megaohms when in total darkness, but a
resistance of only about 2-5k ohms when brightly illuminated. It responds to a
large part of the light spectrum.
The source of light and
LDR is so adjusted with a reflector that light will directly fall on the LDR,
but when robber enters inside then it will block the beam of light and LDR will
be under darkness.
We have made a potential
divider circuit with LDR and 2K
resistance connected in series. Voltage is directly proportional to
conductance so more voltage we will get by this divider when LDR is getting
light and low voltage in darkness. Sensitiveness can be adjusted by variable
resistance. Divided voltage is given to pin 2nd of 555. As soon as LDR gets
dark the voltage of the pin 2 drops 1/3 of the supply voltage and pin 3 gets
high and Buzzer Beeps.
Proteus diagram:-
Advantages:-
•
Construction is easy.
•
Easy to maintain and repair.
•
Comparatively the operation
cost is less.
•
Design is efficient and low
cost.
•
Power consumption is low.
Future scope:-
In
future we can use IR sensor to make light invisible so that unathorized person
will not be able to see the light
Conclusion:
In this project we have done ‘Home security using LASER beam so that
we can spread LASER rays around the home
& If some interrupt occurs in path of LASER
then we will get alerted via buzzer.
