Post By :- Rajbhar Divesh

This project is a standalone automatic fan speed controller that controls the speed of an electric fan according to our requirement. Use of embedded technology makes this closed loop feedback control system efficient and reliable. Microcontroller (ATMega8 / 168 / 328) allows dynamic and faster control. Liquid crystal display (LCD) makes the system user-friendly. The sensed temperature and fan speed level values are simultaneously displayed on the LCD panel. It is very compact using few components and can be implemented for several applications including air-conditioners, water heaters, snow- melters, ovens, heat-exchangers, mixers, furnaces, incubators, thermal baths and veterinary operating tables. ARDUINO micro controller is the heart of the circuit as it controls all the functions. The temperature sensor DHT11 senses the temperature and converts it into an electrical (analog) signal, which is applied to the microcontroller. The sensed and set values of the temperature are displayed on the 16x2-line LCD. The micro controller drives Transistor to control the fan speed. This project uses regulated 12V, 2A power supply. This project is useful in process industries for maintenance and controlling of Boilers temperature.

• With the advancement in technology, intelligent systems are introduced every day. Everything is getting more sophisticated and intelligible. There is an increase in the demand of cutting edge technology and smart electronic systems.

• Microcontrollers play a very important role in the development of the smart systems as brain is given to the system. Microcontrollers have become the heart of the new technologies that are being introduced daily. A microcontroller is mainly a single chip microprocessor suited for control and automation of machines and processes. Today, microcontrollers are used in many disciplines of life for carrying out automated tasks in a more accurate manner.

• Almost every modern day evice including air conditioners, power tools, toys, office machines employ microcontrollers for their operation. Microcontroller essentially consists of Central Processing Unit (CPU), timers and counters, interrupts, memory, input/output ports, analog to digital converters (ADC) on a single chip. With this single chip integrated circuit design of the microcontroller the size of control board is reduced and power consumption is low

• This project presents the design and simulation of the fan speed control system using PWM technique based on the room temperature. A temperature sensor has been used to measure the temperature of the room and the speed of the fan is varied according to the room temperature using PWM technique. The duty cycle is varied from 0 to 100 to control the fan speed depending upon the room temperature, which is displayed on Liquid Crystal Display

We used an LCD shield to display the current temperature and speed of the fan, We also to selected the transistor by the type of fan that we used. In our case We used the well-known P2N2222a transistor and a 12V battery to provide power to the fan and transistor. The DHT11 temperature sensor and red led are powered with 5V from the Arduino board.

As you can see in the sketch on the first line we included the LiquidCrystal library (header) that includes useful functions to use when an LCD is connected to the Arduino board. Then weset the pins for the sensor, LED and fan.

The most important part was to set the variables temp Min and temp Max with our desired values. Temp Min is the temperature at which the fan starts to spin and temp Max is the temperature when the red led lights warning you that the maximum temp was reached. For example if you set temp Min at 30 and temp Max at 35 then the fan will start spinning at 30°C and reach its maximum speed at 35°C.

We store the temperature value in the temp variable and then use some if() functions to check if temp is lower than temp Min and if so let the fan OFF (LOW). The next if() is to check if temperature is higher than the min Temp and lower than the temp Max and if so then use the map() function to re-map the temp value from one value to another. In our case fan Speed will have a value of 32 at temp Min and 255 at temp Max.

Click Here To Download :- Programing And Circuit Diagram