thermistor


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Related to thermistor: thermocouple

thermistor

a semiconductor device having a resistance that decreases rapidly with an increase in temperature. It is used for temperature measurement, to compensate for temperature variations in a circuit, etc.

Thermistor

An electrical resistor with a relatively large negative temperature coefficient of resistance. Thermistors are useful for measuring temperature and gas flow or wind velocity. Often they are employed as bolometer elements to measure radio-frequency, microwave, and optical power. They also are used as electrical circuit components for temperature compensation, voltage regulation, circuit protection, time delay, and volume control. Thermistors are semiconducting ceramics composed of mixtures of several metal oxides. Metal electrodes or wires are attached to the ceramic material so that the thermistor resistance can be measured conveniently. See Bolometer, Electrical resistivity

At room temperature the resistance of a thermistor may typically change by several percent for a variation of 1° of temperature, but the resistance does not change linearly with temperature. The temperature coefficient of resistance of a thermistor is approximately equal to a constant divided by the square of the temperature in kelvins. The constant is equal to several thousand kelvins and is specified for a given thermistor and the temperature range of intended use.

The resistance and heat capacity of a thermistor depend upon the material composition, the physical dimensions, and the environment provided by the thermistor enclosure. Thermistors range in form from small beads and flakes less than 10-3 in. (25 micrometers) thick to disks, rods, and washers with inch dimensions. The small beads are often coated with glass to prevent changes in composition or encased in glass probes or cartridges to prevent damage. Beads are available with room-temperature resistances ranging from less than 100 &OHgr; to tens of megohms, with heat capacities as low as tens of microwatts per degree celsius, and with time constants of less than a second. Large disks and washers have heat capacities as high as a few watts per degree Celsius and time constants of minutes. See Temperature measurement, Time constant

thermistor

[thər′mis·tər]
(electronics)
A resistive circuit component, having a high negative temperature coefficient of resistance, so that its resistance decreases as the temperature increases; it is a stable, compact, and rugged two-terminal ceramiclike semiconductor bead, rod, or disk. Derived from thermal resistor.
References in periodicals archive ?
Thermistors have a temperature sensitivity of 1/10[degrees]C ([+ or -]0.1).
[4] Vaughn C, Gartenhaus J, Strouse G (2006) NIST calibration uncertainties of thermistor thermometers over the range from -50 [degrees]C to 90 [degrees]C.
Nevertheless, RTDs and thermistors are relatively easy to use because they do not have a TC's need for CJ temperature correction.
Thermistors typically have a stability of [+ or -]0.2[degrees]C ([+ or -]0.1[degrees]F) but they can be as stable as [+ or -]0.1[degrees]C (0.06[degrees]F) when using extra precision (XP) thermistors.
Temperature of transducer's thermistors was measured only after 60 minutes after the temperature of the Peltier element reached the target value in order to stabilize the flow of heat.
On the day of the experiments, the rats were taken to the experimental room, and a thermistor (Beta Therm Corp., USA) for measuring [T.sub.brain] was inserted into the brain through the guide cannula.
In this case it was decided to measure the voltage drop across the thermistor. The postulation of an absolute accuracy of 10 mK results in a resolution, which corresponds to 16 bits.
If you get a reading of about 8K-to 10K-ohms, verify the thermistor is functional by placing your fingers gently on the bulb.
This involves a shift away from thermocouples, RTDs, and thermistors to infrared thermometers and fiber-optic temperature sensors.
Digital thermistor units range from handheld to panel-mounted meters with alarm capabilities and accuracies of [+ or -] 2[degrees]F.
They are offered in three configurations and each provides a differential of 2[degrees]F, high accuracy thermistor temperature sensing of 2[degrees]F and a setpoint adjustment of I[degrees]F resolution, which is set by potentiometer.
Designed specifically for driving single-phase switched reluctance motors, the 50A rated FCAS50SN50 SPM smart power module integrates an HVIC with an LVIC, IGBTs, fast recovery diodes and a thermistor in an ultra-compact (44 x 26.8 mm) mini-DIP package.