The document describes an infrared (IR) based security alarm system that uses an IR transmitter and receiver to detect intrusions. When the IR beam is blocked, a photodiode stops producing current which is detected by a 555 timer integrated circuit, triggering an alarm buzzer. The system uses common electronic components like resistors, capacitors, and a battery. It has advantages of being inexpensive, easy for non-professionals to understand and use, and suitable for places needing basic intrusion detection. A potential disadvantage is susceptibility to electromagnetic interference.

1. .
Group # 1
Syed Zain Mehmood 001
Sohail Farman 002
Usama Inayat 016

2. 2
IR Based Security Alarm System
The IR security alarm consists of infrared IR Transmitter, IR
receiver, photodiode and 555 Timer. This detector circuit can be
used to detect any human entry, obstacle

3. 3
Working Principle
In order to use the IR detector circuit to sense the human
entry the IR sensors has to be placed opposite to each other.
Whenever IR radiation is blocked by some obstacle photo
diode stop making current which is detected by the IC.

4. 4
Components
1-IR pair (IR LED and Photodiode)
2-555 timer IC
3-Battery
4-Resistor 100, 10k, 100k, 330, 220 ohms
5-Capacitor 10uF
6-Variable resistor – 10k
7-Buzzer

5. 5
Cost
●
IR Sensor Pair = 40.Rs
●
555 Timer = 30.Rs
●
Capacitor = 20.Rs
●
Resistor = 10.Rs
●
Variable Resistor = 20.Rs
●
Buzzer = 20.Rs
●
Bread Board = 120.Rs
●
Wires = 50.Rs
●
Battery = 60.Rs
TOTAL COST = 350.Rs

6. 6
Circuit Diagram
.

7. 7
Circuit Implementation
.

8. 8
Directions to Use
1-You may see and check the infrared led is glowing or not by using a
camera.
2-Alarm turns off after about 5-10 seconds of getting the contact with IR
again.
3- Range of the circuit is about 5m.
4-Vary the variable resistor to increase or decrease the intensity of the IR
LED for better performance in lighting conditions.
5-Heat sinks should be used with the IC or the IC may get damaged if the
circuit is powered on for a long time.

9. 9
Advantages
A security alarm is a system designed to detect interruption –
unauthorized entry – into a building or other area.
This device has the advantage that it can be known easily to Non-
Professional people easily.
This device is cost effective.
This device can be used in places like Multi-specialty hospitals,
railway stations, Airports. By hearing the sound of a buzzer.

10. 10
Disadvantage
Some IR security electronic systems may operate in
environments susceptible to electromagnetic interference
emitted from sources other than components of the systems