Design and Construction of an Automatic Temperature Control System

Abstract This paper presents the design and construction of a temperature controller system that is capable of maintaining an enclosed area temperature to a desired value. A microcontroller and a temperature sensor are used to control and monitor temperature. LM35 temperature sensor is used to sense temperature and it works linearly with increase in temperature. The microcontroller compares the increase or decrease in temperature with the room or set temperature and passes the information to either the cooling fan or the heater to activate or deactivate accordingly. The set temperature in this design is between 25⁰C and 26⁰C. When the surrounding temperature goes below 25⁰Cthe temperature sensor sends signal to the microcontroller (Atmega 328p) which analyses it by comparing it with the set temperature and then latch the transistor to switch ON the heater. But if the surrounding temperature goes beyond 26⁰C, the temperature sensor detects the temperature change and sends an information to the microcontroller to signal the relay through the transistor to switch ON the fan and automatically puts OFF the heater. The designed system incorporated a buzzer such that it comes ON to alert nearby people in case the temperature goes beyond 37  and the fan fails to cool the environment. The results obtained from laboratory setup agree with that of simulation using proteus software.