mq5

/*
MQ-5
Created by papermindvention.blogspot.com
March 2018
*/
const int buzzer = 3;

void setup() {
 Serial.begin(9600);
 pinMode(buzzer, OUTPUT);
}

void loop() {
  int mq5=analogRead(A0);
  Serial.println (mq5);
  if (mq5 >= 100){ tone(buzzer, 90);  delay (100);  }
  if (mq5 >= 300){ tone(buzzer, 500); delay (80);   }
  if (mq5 >= 500){ tone(buzzer, 2000); delay (50);   }
  else{ noTone(buzzer);  }
}