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Resistance thermometers, also called resistance temperature detectors (RTDs), are sensors used to measure temperature. Many RTD elements consist of a length of fine wire wrapped around a heat-resistant ceramic or glass core but other constructions are also used.
The integrated circuit sensor may come in a variety of interfaces — analogue or digital; for digital, these could be Serial Peripheral Interface, SMBus/I 2 C or 1-Wire.. In OpenBSD, many of the I 2 C temperature sensors from the below list have been supported and are accessible through the generalised hardware sensors framework [3] since OpenBSD 3.9 (2006), [4] [5]: §6.1 which has also ...
The thermocouple temperature is limited also by other materials used. For example beryllium oxide, a popular material for high temperature applications, tends to gain conductivity with temperature; a particular configuration of sensor had the insulation resistance dropping from a megaohm at 1000 K to 200 ohms at 2200 K. At high temperatures ...
A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a mercury-in-glass thermometer or the pyrometric sensor in an infrared thermometer) in which some change occurs with a change in temperature; and (2) some means of converting this change into a numerical value (e.g. the visible scale that is marked on a mercury ...
An NTC is commonly used as a temperature sensor, or in series with a circuit as an inrush current limiter. With PTC thermistors, resistance increases as temperature rises; usually because of increased thermal lattice agitations, particularly those of impurities and imperfections. PTC thermistors are commonly installed in series with a circuit ...
The process is also an example of the Peltier effect (electric current transferring heat energy) as the process transfers heat from the hot to the cold junctions. There are also the so-called thermopile sensors, which are power meters based on the principle that the optical or laser power is converted to heat and the resulting increase in ...
Early technologies included mercury thermometers with electrodes inserted directly through the glass, so that when a certain (fixed) temperature was reached the contacts would be closed by the mercury. These were accurate to within a degree of temperature. Common sensor technologies in use today include: Bimetallic mechanical or electrical sensors.
Such thermometers are usually calibrated so that one can read the temperature simply by observing the level of the fluid in the thermometer. Another type of thermometer that is not really used much in practice, but is important from a theoretical standpoint, is the gas thermometer. Other important devices for measuring temperature include: