Introduction Components Used About MQ-4 Gas & Smoke Sensor Circuit Schematics Code Image of Current System Limitations References

1. Gas & Smoke Detection Using Arduino UNO

2. Introduction
Gas Explosion
An explosion resulting from mixing a gas, typically from a gas leak, with air in the presence of an ignition
source.

3. Components Used
Name Image
Arduino UNO
Generic Breadboard

4. Components Used
Name Image
MQ-4 Smoke & Gas Sensor
Jumber Cables

5. Components Used
Name Image
LED Bulb (1 Green, 1 Red)
Buzzer

6. About MQ-4 Gas & Smoke Sensor
Features
◦ High Sensitivity to CH4, Natural Gas
◦ Fast Response
◦ Simple Drive Circuit
◦ Sensitive to LPG, Butane, Propane, Methane, Alcohol, Hydrogen

7. About MQ-4 Gas & Smoke Sensor
Application
◦ Detecting CH4, Natural Gas
◦ Detecting Smoke, Cooking Fumes

8. About MQ-4 Gas & Smoke Sensor
Notes
◦ Resistance of the sensor is different depending on the type of
the gas
◦ Built-in potentiometer allows to adjust the sensor sensitivity

9. About MQ-4 Gas & Smoke Sensor

10. About MQ-4 Gas & Smoke Sensor
Working Procedure
◦ The greater the gas concentration,
the greater the output voltage
◦ The lower the gas concentration
the lower the output voltage

11. Circuit Schematics
Pin Wiring for MQ-4 Sensor
◦ VCC to 5V
◦ A0 to A5
◦ GND to GND
Pin Wiring for Arduino UNO
◦ Red LED, Arduino Pin 12
◦ Green LED, Arduino Pin 11
◦ Buzzer, Arduino Pin 10

12. Code
Link: https://gist.github.com/660e6c6203ca0a2cef74f842f5774e4d

13. Code
int RED_LED = 12;
int GREEN_LED = 11;
int BUZZER = 10;
int SMOKE_AT_SENSOR_A0 = A5;
int sensor_threshold = 250;
void setup() {
pinMode(RED_LED, OUTPUT);
pinMode(GREEN_LED, OUTPUT);
pinMode(BUZZER, OUTPUT);
pinMode(SMOKE_AT_SENSOR_A0, INPUT);
Serial.begin(9600);
}

14. Code
void loop() {
int value_of_gas = analogRead(SMOKE_AT_SENSOR_A0);
Serial.print("Pin A0: ");
Serial.println(value_of_gas);
// Confirms Gas Reaches Threshold Value
if (value_of_gas > sensor_threshold)
{
digitalWrite(RED_LED, HIGH);
digitalWrite(GREEN_LED, LOW);
tone(BUZZER, 1000, 500);
}

15. Code
// Warn When Reaches 75% of Threshold Value Without Any Sound
else if (value_of_gas * 0.75 > sensor_threshold)
{
analogWrite(RED_LED, 128);
analogWrite(GREEN_LED, 128);
noTone(BUZZER);
}
else {
digitalWrite(RED_LED, LOW);
digitalWrite(GREEN_LED, HIGH);
noTone(BUZZER);
}
delay(1000);
}

16. Image of Current System

17. Limitations
◦ Suitable as a demo project, not for household or commercial use
◦ Threshold value is not properly optimized

18. References
◦ https://arduino.cc
◦ https://sparkfun.com
◦ https://www.tinkercad.com