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Temperature control is a very useful device for the public palace. BY using this technique it is possible to control the speed of the fan automatically. It is possible to convert normal fan into temperature sensitive fan by adding a temperature sensitive logic. By using this technique we not only save the valuable energy but provide a smart automation logic in electrical systems.

IN normal temperature controller we get a output for on and off purpose only but in this project we control the speed of the fan automatically. In brief firstly we convert the temperature into small voltage with the help of lm 35 sensor. LM 35 is temerature sensor convert the temperature in to small voltage at very accurately. Output of the temperature sensor is further converted into digital signal with the help of the ADC. IN this project we use ADC0809 . ADC 0809 is a 8 bit ADC and convert the any analogue signal into digital signal in 100 microsecond. To control the ADC we required a clock pulse, and 4 different signal . All this signal is provided by the controller. IN this project we use ic 89s51 as a main controller. IC 89s51 sense the output from the ADC in hex code. This HEX code is further converted into binary code with the help of program code inside the controller. IN the output device we use LCD display . LCD display display the contents of the display with the help of the ASCII code. ASCII CODE is a special code for displaying the character in the LCD. In the controller we convert the binary code in to ASCII codes with the help of the code conversion program. Temperature sensor by the lm 35 is now display in the ASCII code on the LCD display.

In the controller. We take four different output from the controller. These different output display the different temperature zone step by step.

If the temperature is in between 25 to 30 then zone one is on and if the temperature is in between 30 to 35 then second zone is on. As the temperature increases different zones are on step by one. As the temperature zone increase. LCD display a speed 1 or 2,or3 on the second line of the display.