A device which gives temperature measurement as an electrical signal is called as Temperature sensor. This electrical signal will be in the form of electrical voltage and is proportional to the temperature measurement.
There are different types of sensors used for measuring temperature, such as Contact type temperature sensors, Non-contact type temperature sensors. These are again subdivided as Mechanical temperature sensors like Thermometer and Bimetal. Electrical temperature sensors like Thermistor, Thermocouple, Resistance thermometer and Silicon band gap temperature sensor.
Design of Industrial Temperature Controller for controlling temperature of devices used in industrial applications is one of the frequently used practical applications of the temperature sensor. In this circuit IC DS1621, a digital thermometer is used as a temperature sensor, thermostat, which provides 9-bit temperature readings. The circuit mainly consists of 8051 microcontroller, EEPROM, temperature sensor, LCD display and other components.
LCD is used to display temperature in the range of -55degress to +125degrees. EEPROM is used to store predefined temperature settings by user through the 8051 series microcontroller. The relay whose contact is used for load, is driven by microcontroller using a transistor driver.