1. Thermistor
Thermistor (Thermal Resistor) or Thermal Sensitive Resistor is a type of resistor that is sensitive to changes in temperature, so RDT is often used to detect changes in the resistance of a conductor due to changes in temperature in it.
Thermistor Family
Thermistor Symbol
The working principle of thermistor is to provide a change in resistance that is proportional to the change in temperature. Generally the word thermistor is used for a broader sense, namely an electronic component made of semi-conductor material that has a negative temperature coefficient.
Thermistors have higher sensitivity than thermocouples or RTDs, thermistors are used as temperature sensors, temperature change compensation components or overheating safety devices.
Thermistor Characteristics
The large change in resistance to relatively small changes in temperature makes the thermistor widely used as a temperature sensor which has advantages and high accuracy. Thermistors are formed from mixed metal oxide materials (sintering mixture), chromium, cobalt, copper or nickel.
2. Thermocouple
Thermocouple is one of the transducers that can be used to detect temperature changes. Thermocouples produce accurate and reliable measurements, so they are widely used in industrial processes.
Thermocouple Family
Thermocouple Symbol
Thermocouple can be changed its measuring range based on the combination of materials used, thermocouple is formed by two different types of conductors iron and constantan, wound together and one end of the Thermocouple is a measuring junction and the other end is a transistor as a reference junction or 68o F (20o C), if the end of the thermocouple is heated until there is a temperature change towards the end of the transistor then both ends of the iron conductor and the constantan base of the transistor generate EMF so that it flows electric current in the circuit, so if two conductors of different types are wound together, one part of the base of the coil is heated then both ends of the conductor at the other base will appear EMF or called the potential difference phenomenon, this was first discovered by Thomas Johand Seeback in 1820 and is known as the seeback effect.