The project ‘Temperature Controlled Fan using arduino’ is simply fabricated around arduino uno board and temperature sensor LM35. The projects are good example of embedded system basically designed using closed-looped feedback control system. For proper user interface visual indication we had also used LCD which indicate temperature as well as speed of fan.
Circuit Description of Temperature Controlled Fan using Arduino
The entire circuit of ‘Temperature Controlled Fan using Arduino’ utilize very few components, a MCU (Arduino Uno), a temperature sensor (LM35), a LCD, a motor (Fan), a transistor and few other passive components etc.
Basically IC1 (LM35) is a transducer which convert temperature to electrical signal. As the output is analog in nature so the output is connected to analog input pin (A1) as shown in figure. The temperature sensed is displayed in LCD and control the output of fan as per command in source code. The output is taken from pin D11 which is further given to base of NPN transistor (T1) through resistor R2. Transistor T1 is basically a switching circuit which switch motor (Fan) o and off as per command. A diode is connected across the motor which is also called an fly-back diode used to eliminate voltage spike generate across inductive load.
Operation of Temperature Controlled Fan using Arduino: –
The circuit designed here is used to control the speed of fan by method of pulse-width modulation (PWM) signa. The signal generates here is of low-frequency generally in the range of 30 Hz. As the circuit posted here used a general-purpose transistor for switches which may generate noise because the signal is of pulsed nature.
The core section of the project; software part is written in arduino programming language which is very much as C. The program is compile and burned to arduino uno using arduino IDE. You can directly download the code and use it without any modification.
PARTS LIST OF TEMPERATURE CONTROLLED FAN USING ARDUINO
|Resistors (all ¼-watt, ± 5% Carbon)|
|R1, R2 = 1 KΩ
R3 = 470 Ω
VR1 = 10 KΩ
|C1 = 10 µF, 16 µF (Electrolytic Capacitor)|
|IC1 = LM35 (Temperature Sensor)
T1 = BD139 (NPN Transistor)
D1 = 1N4007 (Rectifier Diode)
LED1 = 5mm LED
LCD1 = 16×2 LCD
Arduino Uno Board
|M1 = 12V DC Operated Fan
12V Battery for Fan