Description:

 In this project we can detect Carbon Monoxide and flammable gases using MQ9 Gas Sensor. A KY-016 RGB LED Module is used to show output in different colours. If a gas is detected, then the RGB LED Module goes Red, Buzzer goes brrrrrr, relay switches and turns ON the electrical device you connected, for example we have used a Bulb (The bulb we use daily in our house). Bulb can be seen from far away so humans can understand that some sus gas is out on loose. You can attach other electrical devices too instead of bulb. Arduino UNO is used to control everything.

Circuit Diagram:

Components:

SR. NO.	COMPONENT	PINOUT DIAGRAM	BUY
1	Arduino UNO (Other Arduinos can be used too)	Arduino UNO Pinout Diagram⇗
2	KY-016 RGB LED Module
3	Buzzer
4	MQ9 Gas Sensor	MQ9 Gas Sensor Pinout Diagram⇗
5	Single Channel or Double Channel Relay Module
6	The Bulb we use everyday
7	That 2 Pin Plug we use everyday

Steps and Info:

1. Get correct components as given. You can buy online or offline. I buy electronics components mostly from Amazon.

2. Start connecting the components. If you are new to connecting components in an electronic circuit, then use a Breadboard or you can straight up make connections using Jumper wires but it will create problem when there will be two or more connections needed at one pin (for example two or more different sensors 5V connection to Arduino’s 5V pin). But before soldering components on a PCB or printing a PCB for your circuit, better try using breadboard so that any errors and mistakes can be observed on breadboard and not after soldering. Or do connections in your way.

3. Now after building the circuit, download the Arduino IDE from https://www.arduino.cc/ website.

4. If you are new to Arduino IDE software, then watch this video we made specially for beginners about Arduino IDE.

5. If you know Arduino IDE then straight up copy the code we given and paste it into the Arduino IDE sketch.

6. Connect the Arduino to your Computer/device. Select a proper port, proper Arduino type and whatever other settings are. Here it is Arduino UNO. (If you don’t know what this all is then watch our video: ).

7. Compile the code and Upload it.

8. If any error occurs then try to troubleshoot it by finding/copy-pasting it into our Solve Errors page https://electronicsprojects.in/solve-errors/, or you can straight up paste the error on Internet and you know the rest. Also check if there are no spelling/syntax errors in the code. Compile the code again once to check if errors are fixed. I have given proper connections and code but still nothing is perfect.

9. Once code compiles and uploads smoothly, you can start testing the working of your circuit/project.

10. Take Carbon Monoxide or any Flammable gas near the MQ9 Gas sensor. The sensor will detect the gas which will turn ON the LED, Buzzer and the electrical device (here Bulb) connected to the relay.

11. If it doesn’t work, then check connections and code. Also you can talk with me and the community through discord. All the links to social is given at the right side of this page.

12. NOTE: So the Flammable gases are flammable, they ignite instantly if they come in contact with fire or even a tiny spark. So work safely and cautiously. Don’t bring any fire source near the gas.

Program Code:

/* https://www.electronicsprojects.in Carbon Monoxide and Flammable Gases Detector using Arduino, MQ9 Gas Sensor and KY-019 RGB LED */

const int REDLED = 2;
const int GREENLED = 3;
const int BLUELED = 4;
const int MQ9 = A5;
int RELAY = 8;
int BUZ = 13 ;
int MQ9Sensor = 0;        
void setup() {
Serial.begin(9600); 
pinMode(REDLED, OUTPUT);
pinMode(BLUELED, OUTPUT);
pinMode(GREENLED, OUTPUT);
pinMode (BUZ, OUTPUT);    
pinMode (RELAY, OUTPUT); 
}
void loop() {
MQ9Sensor = analogRead(MQ9);
if (MQ9Sensor >= 100)
{
digitalWrite(REDLED, HIGH);  
digitalWrite(GREENLED, LOW);  
digitalWrite (BUZ, HIGH) ;// buzz 
delay(50);
digitalWrite (BUZ, LOW) ;
delay(50);
digitalWrite (BUZ, HIGH) ;    
delay(50);
digitalWrite (BUZ, LOW) ;
delay(50);
digitalWrite (BUZ, HIGH) ;        
delay(600);
digitalWrite (BUZ, LOW) ; 
delay(600);
digitalWrite (BUZ, HIGH) ;    
delay(50);
digitalWrite (BUZ, LOW) ;
delay(50);
digitalWrite (BUZ, HIGH) ;    
delay(50);
digitalWrite (BUZ, LOW) ;
delay(50);
digitalWrite (BUZ, HIGH) ;    
delay(300);
digitalWrite (BUZ, LOW) ;
delay(300);
digitalWrite (BUZ, HIGH) ;    
delay(50);
digitalWrite (BUZ, LOW) ;
delay(50);
digitalWrite (BUZ, HIGH) ;    
delay(50);
digitalWrite (BUZ, LOW) ;
delay(50);
digitalWrite (BUZ, HIGH) ;
delay(50);
digitalWrite (BUZ, LOW) ;
delay(50);
digitalWrite (RELAY, LOW); 
}
Else
{
digitalWrite(GREENLED, HIGH);    
digitalWrite(REDLED, LOW);        
digitalWrite (BUZ, LOW) ;
digitalWrite (RELAY, HIGH);
}
Serial.print("Sensor Check = " );                       
Serial.println(MQ9Sensor);     
delay(69);                     
}

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