Introduction
Generally, in security systems that are used in homes, shops, offices, etc., infrared or laser transmitters and receivers are used for accuracy and reliability. But these methods require a lot of monetary investment and infrastructure support. A simple cost effective solution for Security Systems is implemented in this project where I will explain about a PIR based Security Alarm System, in which a PIR sensor is used instead of transmitter or receiver. This saves power consumption as well as it is a low cost implementation. PIR sensor is the short form of Passive Infrared Sensor.
PIR Sensor based Security Alarm Circuit Principle
The main idea of the circuit is to provide security. This is based on PIR sensor with an IC that produces siren. The PIR sensor detects the IR radiations emitted from the humans and it produces a digital output. This digital output is applied to the Arduino UNO. Based on the digital signal from the PIR Sensor, Arduino UNO then triggers the UM 3561 siren IC. Thus it produces the sound when any human is detected. The UM3561 is a ROM IC. It generates multi siren tones like ambulance siren, fire engine siren, police siren, machine gun sound.
PIR Sensor based Security Alarm Circuit Diagram
NOTE: The circuit diagram shows the Oscillator Resistor (between Pin 7 and 8 of UM 3561) as 220Ω but it is 220KΩ.
Circuit Components
PIR sensor Arduino UNO UM3561 Siren IC NPN Transistor – 2N2222 Resistors 10KΩ and 220KΩ Speaker 8Ω Breadboard Connecting Wires
PIR Sensor based Security Alarm Circuit Design
The designed system consists of Arduino UNO, PIR sensor, UM3561 IC, Speaker, transistor and a couple of resistors. The UM3516 IC is a Siren generator IC. It has 8 pins. First and sixth pins are the Sound effect selection Pins. Based on how they are connected, you can choose between 4 different types of sounds. In this project, I have left open both the Pin 1 and Pin 6 to produce a Police Siren. Pin 5 is connected to +5V through an NPN Transistor (which is activated by Arduino UNO’s Pin 4). One end of the 220KΩ resistor is connected to the seventh pin of the UM 3561 IC and the other end is connected to the eighth pin of the IC. Output is taken from the third pin of the IC and it is connected to a speaker through a resistor and transistor. The base of the transistor is connected to the output of the IC through a resistor of 10KΩ. Emitter pin is connected to the ground while one end of the speaker is connected to the collector, while the other end is connected to +5V. Coming to the PIR Sensor, its output is connected to Pin 3 of Arduino.
Code
Working of PIR Sensor based Security Alarm System
PIR Sensor Based Security Alarm System Applications
This can be used in the museums to protect the valuable things. This can also be used as an automatic door bell circuit that rings the bell when human is detected. This can be used in defense applications to detect the humans in war field. This can be used in toy applications that produce sound.
Limitations of this Circuit
PIR sensor pot should be adjusted in such a way to detect the humans only. This can detect the human only within its range of 5 meters.
IC pin 2, PIR pin 3 should it be connected to -ve 9v supply? Comment * Name * Email * Website
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