TechieYan Technologies

Smoke Detector Alarm

smoke detector alarm project from techieyan technologies


A smoke detector alarm automatically detects the smoke and gives a warning to be aware of it. Most accidents occur due to the absence of humans in the right place at the right time. As soon as smoke is detected the circuit is activated and the buzzer is turned on. This can prevent many accidents from occurring and also help to take necessary steps to take as early as possible. This can be mostly used in industries where many chemicals are used. As there are many chances of various chemicals getting reacted and producing harmful gases which can be harmful to human health, to detect such gases we can use this device to fire and it can also be used. and there are many more real-time applications where smoke detection can be used. This device helps to detect unhealthy gases and give an alert and prevent damage from happening.


Smoke alarms detect particles in the air. It can work when there might be a fire accident or electric circuit breakdown in houses, industries, or restaurants.

As per the WHO, around 7 billion people die every year due to exposure to fine particles in polluted air. As accidents are growing continuously one needs to be more careful about them and this project can help to reduce the risk of  accidents. In the project, an Arduino-based smoke detector is built to prevent harmful disasters from occurring and be aware of disasters to happen. There are many advantages of this project, it is not expensive, reliable, it’s easy to build, easy to modify as per the requirement, has an early warning, and has low power consumption. If any smoke is detected then the circuit is activated and the buzzer is turned on and the led light starts to blink so, that one can take a major step before any large disaster happens 

Components Required

Hardware Requirements

  • Arduino Uno: Arduino Nano is a microcontroller from Arduino Family, a friendly board based on the ATmega328. Nano has 22 Input/Output pins. 14 are digital pins and 8 are analog pins. 

Automatic smoke detector alarm Arduino circuit

For more details,  pinout and datasheet, you can visit :

  • Gas sensors: Gas sensors (also known as gas detectors) are electronic devices that detect and identify different types of gases.
  • Buzzer: The buzzer is an electric-sounding device that generates sounds.
  • LED: A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it. 

Software Requirements

  • Arduino Ide : Arduino IDE (Integrated development environment) is software that is used to dump the program into boards. Arduino- IDE’s major use is to build electronics-related projects. Arduino is an open-source platform simple and easy-to-understand platform for coding.


Block diagram

The following block diagram of smoke detector alarm gas sensor is an input device that sends data to Arduino. Buzzer and led are output devices that receive information from the Arduino  

smoke detector alarm block diagram

Flow Chart

A flowchart is a diagram that shows a process’s steps in proper order. Similarly, the following flowchart talks about the steps involved in this smoke detector alarm project and the sequential flow of the code also. So, as it starts, first, the smoke sensor detects the presence of harmful smoke, and If the sensor detects the smoke then the led and buzzer get activated. Else the buzzer and led are turned off

flow chart of smoke detector

*website used to make Flow Chart and Block Diagram :

Connections and Pins

Smoke Sensor

The smoke sensor has 4 pins

The following pin connection is about the connection of the gas sensor with Arduino nano. The gas sensor has 4 pins, the MQ-3 is connected to 5v of Arduino nano, the analog pin is connected to A0 and the Ground (GND) is connected to the GND of Arduino Nano.

smoke alarm sensor pin connections to arduino


The buzzer has 2 pins

The below pin connection is about the connection of the buzzer with Arduino nano. The buzzer has 2 pins, the Buzzer is connected to 5v  of Arduino nano. The other pin is connected to the GND of the Arduino nano.

smoke alarm buzzer pin connection with arduino


LED has 2 pins

The pin connection is about the connection of the led with the Arduino Nano. LED has 2 pins, the LED is connected to 5v of Arduino Nano. And the other pin is connected to the digital pin of Arduino Nano.

smoke alarm pin connections to arduino

Circuit diagram

Follow the below circuit diagram to understand the connection made to different devices.

Note: Make sure to take proper precautions while connecting the components.

smoke detection circuit diagram


The next step after setting up the connection is to upload code to Arduino Nano and power it. When the system is turned on, Arduino continues to watch for smoke if the smoke gets detected then led and a buzzer will get activated else it remains off.


Thus we conclude smoke detection is used for safety purposes. This will help to avoid accidents and save the lives of people, even helping avoid damage caused to humans. The main objective of this smoke detector alarm project is to provide a reasonable price that can help everyone. 

Working Code of Smoke Detector Alarm

#define smoke A0                     //smoke sensor pin connecetd to pin A0 of Arduino Nano 
 #define Buzzer 8                     //buzzer pin connecetd to pin 8 of Arduino Nano 
 #define LED 13                       //LED pin connecetd to pin 9 of Arduino Nano 
 #define Thres_Val 460                //Threshold value of MQ3 reading should  be trigger
 int value;                           //integer value is define to store the output of MQ3 sensor           
 void setup() {
   pinMode(smoke, INPUT);             //Set MA3 as INPUT device
   pinMode(Buzzer, OUTPUT);           //Set Buzzer as INPUT device
   pinMode(LED, OUTPUT);              //Set LED  as INPUT device
 void loop() {
   value = analogRead(smoke);          // reads the analog value from smoke sensor
  if ( value > Thres_Val )             //if smoke is detected
     digitalWrite ( LED , HIGH );      // turns the LED on
     digitalWrite(Buzzer,HIGH);        // turns the buzzer on  

 else {
     digitalWrite(LED, LOW);           //  turns the LED off
     digitalWrite(Buzzer,LOW);         //  turns off 
    delay (500);                      

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