Laser Intruder Alarm System

3283 Words Nov 29th, 2012 14 Pages
This Document contains Project Report of Autumn 2012 of Course CT-111.

 An Alarm is a type of security equipment that can be used to safeguard houses and property.  Now a days Burglar Crimes are continually rising with each passing day.  Many have lost homes and families through violent burglaries in many countries  Some of them lost most precious things such as Jewelry, Vehicles, huge investments in banks etc..  This led to the development of ALARM SYSTEM

Basic circuit

Alarm Interface:
 We used LDR to detect Laser Light.  LDR pin was Fed to Op-Amp input leg.  Clock pulse to 4017 was taken from Op-Amp output pin.

Light Dependent Resistor (LDR)
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void loop() { int a0=analogRead(A0); int a1=analogRead(A1); int a2=analogRead(A2); // four variables a0-a3 are integer variables // these take in analog input values from the // corresponding ports.

int a3=analogRead(A3); // the input voltage what ever voltage is represented as a 0-1024 bit value. if( !(a0>300 && a1>300 && a2>300 )) { If(a3>500) { tone(8,1000); buzzer at 8 /* a pwm signal with duty-cycle 50% is sent to a port with a time period of 1sec.*/ delay(100); } } noTone(8);

Transmitter & Receiver Interface:
 Say in some apartments or malls if we use Laser alarm system, if there is any robbery the alarm should beep at the security guard/control room.  We will transmit the message to all security systems in the mall/apartment So that we can alert them.  We used RF-Transmitter and Receiver to transmit the message.  We used Encoding and Decoding Schemes for protected transmission.  For that we used HT12E(Encoder), HT12D(Decoder).  For Demonstration purpose we are using LED’s to show the received message.

Transmitter & Receiver:
 RF module comprises of an RF Transmitter and an RF Receiver. The transmitter/receiver (Tx/Rx) pair operates at a frequency of 434 MHz.  In this RF system, the digital data is represented as variations in the amplitude of carrier wave. This kind of modulation is known as Amplitude Shift Keying (ASK).  An RF transmitter receives serial data and transmits it wirelessly through RF
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