Published June 29, 2022 © CC BY

Gas detector CO & CH4

This project guide how to make portable gas detector CO & CH4

IntermediateFull instructions provided196

Things used in this project

Hardware components

NodeMCU ESP8266 Breakout Board

Axial Fan, 12 V

Story

Hi there, this project will guide you how to make a portable gas detector (CO & CH4) which can be used to detect level of exhaust fume of your motorcycle or car. The case is made from MDF wood (cut by cnc laser machine). It is compact as a portable, you can use it easily

Step 1. Part list

1. ESP8266

2. Gas sensor MQ-9B (CO & CH4)

3. Battery

4. Fan

5. OLED LCD

6. Switch

7. Battery holder

8. MDF wood 3mm

9. Bread-board cables

Step 2. About the sensor MQ-9B (CO & CH4)

I got the sensor from DF-Robot https://www.dfrobot.com/product-688.html

This sensor will feedback signal to Microcontroller via Analog, so we only need 1 AI input pin to read result.

The sensor can sense both CO (produced by exhaust fume from vehicles) & CH4 (fuel gas for oven in your kitchen). However, as I test, the sensor can't tell you exact how many (% or ppm) of CO and CH4, it just feedback both of them (CO or CH4) as level % of sensor ability. I think the sensor is useful for you to detect both those gas in case you want to compare exhaust fume of your car and your friend car, or detect if your oven have leakage fule gas

Step 3. Circuit

You can test the circuit in breadboard to see how it works.

The circuit will supply power by 2 battery 18650 (3.7*2 = 7.4VDC)

When switch ON, power will supply for ESP8266 (V-in of ESP8266 can support 4.5V-10V), the fan will run (even fan 12VDC, but it still works at 7.4VDC) to inhale sample air to the sensor. Then, result will show on OLED LCD

At first time power on sensor, it will result about 30-40%. It is not correct result because the sensor is in warming up time, as my experience, it need about 1-2hrs (or even more) to sensor get stable at 8-9%.

When it is stable at 8-9%, now we can put the sensor to place has many CO & CH4 like exhaust nozzle of your motocyle, then start engine to see result goes up.

Step 4. Arduino code

(check code section)

Step 5. Make the case

I use MDF wood 3mm thickness, cut by laser cnc, then stick together by glue to make the case, then place all things to the box. I got the beautiful and compact portable gas detector

Vector file cnc for laser cutting: https://bit.ly/3QVACtQ

Step 6. See how it works

Let's check the video of my result at my channel. I hope you like my works, please leave your comment to disscuss. Thank you.

Code

Gas detector

///Arduino Sample Code
#include <Adafruit_GFX.h>       // Include core graphics library for the display
#include <Adafruit_SSD1306.h>   // Include Adafruit_SSD1306 library to drive the display
#include <Fonts/FreeMonoBold18pt7b.h>  // Add a custom font
#include <Fonts/FreeMono9pt7b.h>  // Add a custom font

Adafruit_SSD1306 display(128, 64);            //Create display


void setup()
{
  Serial.begin(9600); //Set serial baud rate to 9600 bps

  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);  // Initialize display with the I2C address of 0x3C
  display.clearDisplay();  // Clear the buffer
  display.setTextColor(WHITE);  // Set color of the text
  
}
void loop()
{
  double val;
  val=analogRead(0);//Read Gas value from analog 0; value 0~1023
  val=(val/1023)*100;
  Serial.println(val,DEC);//Print the value to serial port
  delay(300);

  display.clearDisplay();  // Clear the display so we can refresh

  // Print text:
  display.setFont(&FreeMono9pt7b);
  display.setCursor(45,20);  // (x,y)
  display.println("GAS");  // Text or value to print

  // Print temperature
  char string[10];  // Create a character array of 10 characters
  // Convert float to a string:
  dtostrf(val, 3, 0, string);  // (<variable>,<amount of digits we are going to use>,<amount of decimal digits>,<string name>)
  
  display.setFont(&FreeMonoBold18pt7b);  // Set a custom font
  display.setCursor(20,50);  // (x,y)
  display.println(string);  // Text or value to print
  display.setCursor(90,50);  // (x,y)
  display.println("%");  // Text or value to print


  display.display();  // Print everything we set previously

  
}

Credits

engineer2you

24 projects • 93 followers

i'm mechatronics engineer who loves making funny project and sharing for you. See me at: https://www.youtube.com/c/engineer2you

Gas detector CO & CH4

Things used in this project

Hardware components

Story

Step 1. Part list

Step 2. About the sensor MQ-9B (CO & CH4)

Step 3. Circuit

Step 4. Arduino code

Step 5. Make the case

Step 6. See how it works

Schematics

Gas detector circuit

Code

Gas detector

Credits

engineer2you

Comments

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Gas detector CO & CH4

Gas detector CO & CH4

Things used in this project

Hardware components

Story

Step 1. Part list

Step 2. About the sensor MQ-9B (CO & CH4)

Step 3. Circuit

Step 4. Arduino code

Step 5. Make the case

Step 6. See how it works

Schematics

Gas detector circuit

Code

Gas detector

Credits

engineer2you

Comments

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