Temperature Sensor.

Reauben Samson has made an incubator and we need to check if it is working. We used a digital thermometer, it gives us different readings after every 15 minutes and we concluded it does not work so now we are building a temperature sensor using the Arduino Uno board and LM35 temperature sensor. The main aim is to keep a constant temperature using a light bulb as our heat source. We will be using a CPU fan to cool down the light bulb and to keep the incubator at a certain threshold temperature.

Parts list: CPU fan LED Light bulb (230 VOLT, 75 WATTS) LM 35 (temperature sensor) Diode (2N3904 - E25) Relay (JQC-3F 6 VOLT) Wire Arduino Uno

 Arduino Code LM 35 Temperature Sensor  float tempC;                           // create variable to store the temperature in. int tempPin = 0;                       // Attach vout to analog pin 0. int led = 13;                          // attach led to pin 13. int fan1 = 3;                          // attach base of transistor to digital pin 3. int pos = 0;                           // create variable to store the position of the servo motor. void setup                           // Will execute once at the start of the code. { Serial.begin(9600);                   // opens serial port, sets data rate to 9600 bps pinMode (led, OUTPUT);               // sets the led pin 13 up as an output. pinMode (fan1, OUTPUT);              // sets the fan1 pin 3 up as an output. }

void loop                            // code here will continue to replay nutil powered off. {  tempC = analogRead(tempPin);          // read the analog value from the lm35 sensor. tempC = (5.0 * tempC * 100.0)/1024.0; // convert the analog input to temperature in centigrade. Serial.print((byte)tempC);           // send the data to the computer.

if (tempC > 38)                    // creates bool expression for analyzation. if it evaluates to true, {                                  // the body of the if statement will execute. digitalWrite (led, HIGH);        // turns on led. digitalWrite (fan1, HIGH);       // turns on fan1. }    else                                // if the if equation evaluates to false the else statement will execute. {      digitalWrite (led, LOW);          // turns off led. digitalWrite (fan1, LOW);        // turns off fan1. }  delay(3000);                          // wait 3 seconds before redoing the loop. }