Automatic Solder Fume Extractor

1/*Automatic Solder fume Extractor
2 * BY 
3 * ABID HOSSAIN
4 * The  Fume Extracture turns on when it detects any somoke....
5 * 
6*/
7
8int  SensorPin = A5;
9int led = 7;  
10float SensorOut = 0;
11float SensorVo = 0;
12float  Dust = 0;
13float Voltage_noDust = 0.12; //calibrate by changing this
14float  K = 0.5;               //Sensitivity from the datasheet 0.5V/ugm/m^3
15int relay=  2;
16
17void setup()
18{
19 pinMode(led,OUTPUT);
20 pinMode(relay,OUTPUT);
21  Serial.begin(115200);
22 delay(10);
23 digitalWrite (relay, HIGH);
24 delay(5000);
25  digitalWrite (relay, LOW);
26
27}
28
29void loop()
30{
31  digitalWrite(led,LOW);          //turning on the led
32  delayMicroseconds(280);         //wait for 0.28ms
33  SensorOut = analogRead(SensorPin);    //read the sensor output voltage
34  delayMicroseconds(50);                //wait for 50us
35  digitalWrite(led,HIGH);               //turning  off the led
36  delayMicroseconds(9670);              //wait for (10000-280-50)=9670us
37  SensorVo = SensorOut*(5.0/1024);      //calculating sensor output voltage
38  Dust = (SensorVo-Voltage_noDust)*100/K;     //calculating Dust density(ugm)/m^3
39  
40  if ( Dust < 0)
41  {
42    Dust = 0.00;
43  }
44//Serial.println(Dust);  
45//delay(100);
46
47if (Dust > 100){
48 digitalWrite (relay, HIGH);
49 delay(5000);
50}
51else  {
52 digitalWrite (relay, LOW);
53}
54}
55