Temperature Based Automatic Fan Speed Controller Using Arduino

Temperature sensor LM35 sensor the temperature and convert it into an electrical which applied to the algema328 microcontroller of the arduino UNO board. The analog value converted into digital value. The sensor value of the temperature and speed of the fan are displayed on the LCD. When the temperature exceeds 30 ° the fan starts rotating. A low frequency pulse width modulation (PWM) signal, whole duty cycle & varied to adjust x fans speed s used. An single, small, pass transistor like 2N222 or BD139 can be used here it is efficient because the pass transistor is used as a switch.