On this straightforward DIY Problem, I am going to current you design and implement a PIR Sensor based totally Security Alarm System. I’ve designed this circuit using Arduino because the precept controller and naturally the PIR Sensor itself. Furthermore, I’ve used UM3561 IC, which is a Siren Generator IC, to produce the obligatory Alarm sound via a Speaker.


Sometimes, in security strategies which will be utilized in properties, shops, workplaces, and so forth., infrared or laser transmitters and receivers are used for accuracy and reliability. Nonetheless these methods require quite a few monetary funding and infrastructure assist.

A straightforward worth environment friendly decision for Security Applications is carried out on this enterprise the place I am going to make clear just a few PIR based totally Security Alarm System, via which a PIR sensor is used in its place of transmitter or receiver. This protects vitality consumption along with it is a low worth implementation. PIR sensor is the transient sort of Passive Infrared Sensor.

PIR Sensor based totally Security Alarm Circuit Principle

The first considered the circuit is to produce security. That’s based totally on PIR sensor with an IC that produces siren. The PIR sensor detects the IR radiations emitted from the folks and it produces a digital output. This digital output is utilized to the Arduino UNO.

Primarily based totally 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 totally Security Alarm Circuit Diagram

PIR Sensor based Security Alarm System using Arduino Circuit Diagram

NOTE: The circuit diagram reveals the Oscillator Resistor (between Pin 7 and eight of UM 3561) as 220Ω nevertheless it is 220KΩ. 

Circuit Elements

  • PIR sensor
  • Arduino UNO
  • UM3561 Siren IC
  • NPN Transistor – 2N2222
  • Resistors 10KΩ and 220KΩ
  • Speaker 8Ω
  • Breadboard
  • Connecting Wires

PIR Sensor based totally Security Alarm Circuit Design

The designed system consists of Arduino UNO, PIR sensor, UM3561 IC, Speaker, transistor and some resistors. The UM3516 IC is a Siren generator IC. It has eight pins. First and sixth pins are the Sound influence selection Pins. Primarily based totally on how they’re linked, you presumably can choose between 4 varied sorts of sounds.

On this enterprise, I’ve left open every the Pin 1 and Pin 6 to produce a Police Siren. Pin 5 is linked to +5V via an NPN Transistor (which is activated by Arduino UNO’s Pin 4).

One end of the 220KΩ resistor is linked to the seventh pin of the UM 3561 IC and the other end is linked to the eighth pin of the IC. Output is taken from the third pin of the IC and it is linked to a speaker via a resistor and transistor.

The underside of the transistor is linked to the output of the IC via a resistor of 10KΩ. Emitter pin is linked to the underside whereas one end of the speaker is linked to the collector, whereas the other end is linked to +5V.

Coming to the PIR Sensor, its output is linked to Pin Three of Arduino.


PIR Sensor based Security Alarm System using Arduino Image 2

Working of PIR Sensor based totally Security Alarm System

  1. Make the connections as per the circuit diagram and alter on the circuit.
  2. The PIR sensor is powered and it detects the IR rays emitted from any human.
  3. This PIR sensor has quite a lot of 5 meters. You presumably can modify the pot supplied for the sensor to vary this distance.
  4. When any human is detected, the PIR sensor outputs a logic HIGH price i.e. voltage of three.5V to 5V to ARduino UNO’s Pin 3.
  5. As shortly as a result of the Arduino detects logic HIGH on Pin 3, it makes the Pin 4 HIGH for a size of 10S. All through this time, the Siren IC UM3561 is activated as its Pin 5 equipped with +5V.
  6. The siren generator has an oscillator internally, to produce the sound.
  7. The oscillator circuit is tuned to a certain frequency and using a 220KΩ resistor externally.
  8. Then it is handed to the administration circuit, which is able to rely upon tone selection pins.
  9. These tone selection pins decide one tone from utterly completely different tones produced by the IC.
  10. Thus oscillations along with chosen tone are despatched to the take care of counter. The take care of counter then sends the data to the ROM.
  11. ROM then sends the tone on the output pin 3.
  12. The output is given to the NPN transistor to amplify the siren.
  13. The underside of the transistor will get voltage from output pin of the siren generator.
  14. Transistor begins conducting when it can get the cutoff voltage on the bottom and the speaker is harmful pin and is linked to the underside.
  15. Thus sound produced can be heard from the speaker when human is detected.
  16. Inside the present circuit, it produces Police Siren sound.

PIR Sensor Primarily based Security Alarm System Functions

Limitations of this Circuit

  • PIR sensor pot should be adjusted in such a choice to detect the folks solely.
  • This might detect the human solely inside its differ of 5 meters.



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