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Thermoelectric Devices and Their Functions
By Angela Oliver
Thermoelectric devices are an entire group of their own in the world of electronic components. By several different methods, thermoelectric devices convert temperature input into electrical output and vice versa. The thermoelectric effect states that any type of conductor, such as metal, when subjected to changing temperatures will generate voltage. Thermoelectricity is the principle behind the function of many temperature driven devices, including space probes that use the heat of radioactive decay. Here is a look at the different thermoelectric devices and their functions.
Thermistor: A thermistor is a device whose name is the combination of thermal and resistor. This device relies on its ability to measure temperature change depending on its change resistance in relation to changing temperature. Thermistors are classified as PTC or NTC as resistance increases or decreases with temperature change. Thermistors are used in a number of temperature measuring devices including most familiar, a digital thermostat or a battery charger, and more technically in power fuses and circuits.
Thermocouple: Thermocouples are also used as temperature sensors, however, they can also convert thermal potential difference into electric potential difference. They are inexpensive, have standard connection systems and are able to measure a wide range of temperatures with little error. Thermocouples are best used for measuring large temperature ranges, and not small temperature ranges where high accuracy is required. The most familiar thermocouple is used in the pilot lights of heaters. The thermocouple is placed in the tip of the pilot light and supplies gas to the heater as long as the pilot is lit. If the pilot goes out, the temperature drops, and the power supply to the valve is halted, stopping the supply of gas.
Thermopile: Thermopiles are a series of thermocouples connected together, thus allowing for higher voltage. Thermopiles are used in large convection heaters because higher voltage is required for the pilot valve safety system. Thermopiles are used for measuring radioactive intensity. Commercial thermopiles are so effective they are
used in laser power meters.
All of these devices operate under the same fundamental effect called the thermoelectric effect, or more specifically, the Peltier-Seebeck effect. A Peltier cooler is a heat pump which transfers heat from one side of the device to the other. It is also referred to as a thermo-electric cooler (TEC). All of these devices are essential for monitoring temperature in a variety of situations including industrial, scientific, food and medical research to ensure safety and provide necessary information.
About the Author:
Angela Oliver is a contributing author for HRent.com, H and R Enterprises, distributor of obsolete and hard to find electronic components including thermoelectric devices, integrated circuits, transistors, diodes and more. Please visit the site at Hrent.com to view the large inventory of electronic components.
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