How do you calculate 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 does a thermistor calculate temperature?
A thermistor is a resistance thermometer, or a resistor whose resistance is dependent on temperature. The term is a combination of “thermal” and “resistor”. When temperature increases, the resistance increases, and when temperature decreases, resistance decreases. This type of thermistor is generally used as a fuse.
How do you find thermistor voltage?
First find the total resistance of the voltage divider. Then find the current through the components. Now find the voltage across the thermistor. The voltage across the thermistor, V t h = 49.5 m V .
What is the temperature range of a thermistor?
The typical operating temperature range of a thermistor is −55 °C to +150 °C, though some glass-body thermistors have a maximal operating temperature of +300 °C.
How is NTC beta calculated?
The beta value of an NTC Thermistor is calculated using only two temperatures over a given range and is not the most accurate way to calculate the R vs. T curve. A more accurate method is to use the Steinhart and Hart method, which uses three temperatures over a given range.
How do you measure a thermistor?
Thermistor Response to Temperature 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.
How to calculate the resistance of a thermistor?
Alpha is negative for NTC thermistors and positive for PTC thermistors. Beta is defined as follows: Thus to calculate R2 you can use this formula: Likewise, we can compute a temperature for a measured resistance: T 2 = T 1 *B/ln (R 1 /R 2 ) / ( B/ln (R 1 /R 2 ) – T 1 ) , Note that T has units of Kelvin.
Why is the thermal time constant important for the thermistor?
The thermal time constant is a measure of how fast the thermistor can adapt to temperature changes. If you want to measure quick changes in temperature, then a small time constant becomes important. Knowing the end accuracy of a family of thermistors can be challenging given the multitudes of parameters on a datasheet.
Is the Alpha of a thermistor positive or negative?
Alpha the temperature coefficient is often denoted as TCR on datasheets. Alpha is negative for NTC thermistors and positive for PTC thermistors. Beta is defined as follows: Thus to calculate R2 you can use this formula:
When to use beta in a Temperature Calculator?
Beta is temperature dependent, and is specified between two temperature points, and can be used to calculate Temperature between the specified temperatures, with a rated accuracy. For example, for a beta specified between 25 and 85 it will often be denoted as B 25/85 .