What are the characteristics of a thermistor?
Thermistors are temperature-dependent resistances, normally constructed from metal oxides. The resistance change with temperature is high compared with the metallic resistances, and is usually negative: the resistance decreases with temperature increase. The temperature characteristics are highly nonlinear.
What is IV characteristics of thermistor?
I-V graph for Thermistor For the thermistor, its resistance reduces with the temperature. In case of Thermistor, at higher voltage range when current flow becomes higher the temperature of the conductor also rises, but in this case this reduces the resistance of the thermistor.
What is the resistance of a thermistor?
Thermistors are characterised by their base resistance as well as their “B” value. The base resistance, for example, 10kΩ, is the resistance of the thermistor at a given temperature, usually 25oC so is defined as: R25.
What does thermistor resistance depend on?
A thermistor is a resistance thermometer, or a resistor whose resistance is dependent on temperature. The term is a combination of “thermal” and “resistor”. It is made of metallic oxides, pressed into a bead, disk, or cylindrical shape and then encapsulated with an impermeable material such as epoxy or glass.
What is the main function of a thermistor?
Thermistors are thermally sensitive resistors whose prime function is to exhibit a large, predictable and precise change in electrical resistance when subjected to a corresponding change in body temperature.
What is the purpose of a thermistor?
Why does the resistance of a thermistor decrease with temperature?
Types. Depending on materials used, thermistors are classified into two types: With NTC thermistors, resistance decreases as temperature rises; usually due to an increase in conduction electrons bumped up by thermal agitation from valency band.
How do you find the resistance of a thermistor?
The percent resistance tolerance is determined by multiplying the specified temperature tolerance by the NTC of the thermistor at the given temperature point. NTC (%/°C) × Temperature Tolerance (± °C) = ± % Resistance Tolerance.
How do you measure the resistance of a thermistor?
As with any resistor, you can use the ohmmeter setting on your multimeter to measure thermistor resistance. The resistance value displayed on your multimeter should correspond to the ambient temperature near the thermistor. The resistance will change in response to temperature change.
What makes a good thermistor?
Higher temperature applications generally use higher resistance thermistors (above 10,000Ω). Some materials provide better stability than others. Resistances are normally specified at 25°C (77°F). Thermistors are accurate to approximately ± 0.2°C within their specified temperature range.
Why does resistance decrease with temperature in a thermistor?
What kind of resistance does a thermistor have?
Thermistors are either NTC type, whose resistance decreases with increasing temperature, or PTC type, whose resistance increases with increasing temperature. Each type has unique features and distinct advantages.
What are the characteristics of a NTC thermistor?
The key characteristics of NTC and PTC thermistors include : Resistance temperature (R–T) characteristics: Describe how resistance changes as temperature changes in a thermistor. Most thermistor manufacturers provide tables, R–T curves, and coefficients for their thermistor products.
What are the beta tolerances of a thermistor?
For bead-type thermistors, beta tolerances are in the order of ±1% to ±5%; for metallized surface contact type, beta tolerances range from ±0.5% to ± 3%. Heat capacity: Is the product of the specific heat and mass of the thermistor.
How are thermistors used for temperature control and compensation?
This high sensitivity to temperature changes makes thermistors extremely useful for precision temperature measurements control and compensation.Thermistors are widely used in applications which involve measurements in the range of — 60°C to 15°C. The resistance of thermistors ranges from 0.5 Ω to 0.75 MΩ.