# thermistor temperature calculator

January 1, 2021 By No Comment

Resistance varies between 11.8 kΩ to 12 kΩ at 26-27°C. Attached is my Thermistor Calculator component ("myThermistor"). temperatures. If you want to I don't know the B-constant. Knowing the end accuracy of a family of thermistors The Consult the … Another way to describe polynomials is that they provide a curve-fit equation for a slope. temperature points, and can be used to calculate Temperature between the … Since the thermistor is a variable resistor, we’ll need to measure the resistance before we can calculate the temperature. resulting temperature can be off due to variances in the lot. We can figure out the resistance at a given temperature using the BT1/T2= 1/(1/T1-1/T2)ln(R1/R2) Thermistors function as a heating element and thermo-sensitive device, and play an active role in various applications, such as temperature sensors, circuit protection, and temperature compensation. The temperature coefficient of a thermistor is used when calculating the tolerance of a thermistor in terms of temperature. In this way it acts as a automatic … From the equation above we can Apart from the standard Steinhart-Hart equation other forms have been found. C parameter is set to zero. specified temperatures, with a rated accuracy.For example, for So we get maximum deviation when alpha is selected at That is the resistance value decreases if the temperature of the thermistor is increased and it increases if the temperature is decreased. Note that Let’s build a basic thermistor circuit to see how it works, so you can apply it to other projects later. Most manufacturers will specify alpha and beta, and greater the accuracy will be. In the case of an over-current situation, the thermistor body temperature rises and quickly reaches the transition temperature. MIL-PRF and NSAS/GSFC parts always use MIL-spec curves. ). The circuit operates at 6V Power Supply. // This helps calculate the thermistor's resistance (check article for details). To find percent tolerance - Multiply degree tolerance by NTC value. Note that the values for A1,B1,C1,D1 are different than EI Sensor Technologies is pleased to offer a wide variety of Thermistor elements with resistance values ranging from 100 ohms to 5M ohms and tolerances such as ±1%, ±2%, etc. Beta is temperature dependent, - T1 ) , Note that T has units of Kelvin. The temperature coefficient of resistance or alpha (∝) of a thermistor is defined as the ratio of the rate of change of resistance with temperature to the resistance of the thermistor at a specified temperature (T), as shown by the following expression: Where T = temperature in Kelvin and R = Resistance in Ohms at temperature T. However, in order to rate a thermistor, the standard temperature that most manufacturers use is the 25 degree Celsius which is equivalent to room temperature. (The most general form of the equation contains a (IN(R))2 term, but this is frequently neglected because it is typically much smaller than the other coefficients, and is therefore not shown above. The more narrow the temperature range, the However, for a group of thermistors, the For application with lower CPU power a simplified form of the Steinhart-Hart equation can be used. So the most common and market available resistance value for thermistor temperature sensor is 5k ohm, 10k ohm, 50k ohm, 100k ohm and even 200k ohm at 25 degree. Thermistors operate over a relatively limited temperature range, typically -50 to 300°C depending on type of construction and coating. Question: A 10kΩ NTC thermistor has a B value of 3455 between the temperature range of 25oC and 100oC. Calculate its resistive value at 25-degree celsius and again at 100oC. Rnew=R0*exp-B* ((1/273+Tref)- (1/273+Tnew)) Measure temperature using Arduino and NTC thermistor NTC (Negative Temperature Coefficient) thermistor has a characteristic of non-linear inverse varying resistance with respect to the temperature change. data sheet should specify the tolerance in %C. calculate resistance value for a given temperature for an NTC thermistor with given Steinhart-Hart coefficients and ; evaluate Steinhart-Hart coefficients for an NTC thermistor descibed by a temperature-resistance table. Arduino IDE These units are rugged and unaffected by severe environmental exposures. General Description The Thermistor Calculator component calculates the temperature based on a provided voltage measured from a thermistor. Polynomial equations are the most accurate way to get a temperature from a thermistor. The Beta value is measured in the value °K (Kelvin). Many times manufactures neglect to put these A thermistor is a type of resistor whose resistance is strongly dependent on temperature, more so than in standard resistors.The word is a combination of thermal and resistor.Thermistors are widely used as inrush current limiters, temperature sensors (negative temperature coefficient or NTC type typically), self-resetting overcurrent protectors, and self-regulating heating elements (positive temperature … Calculating Temperature using Thermistor. Subtract 273.15 to convert Kelvin to Celsius. The device rating is typically a resistance value at a particular temperature, such as 4.7 kΩ at 25 °C. Hence, R T0 = 4700 Ω and T 0 = (25 °C + 273.15) Defense R – T (Resistance vs. Temperature Tables) – M23648 and M32192 Defense Ratios for defense and aerospace applications use slightly different values than QTI’s standard curves. Note that the equation is extremely Steinhart-Hart Calculator - The Steinhart–Hart equation is a model of the resistance of a semiconductor at different temperatures. Hardware 1. Thermistors (Temperature Sensors) Heat is generated by the applied voltage and current, and the resistance changes with the change of temperature. When the over-current or short-circuit situation is solved and the thermistor is cooled down again, the circuit will function as normal again. Since the thermistor is a variable resistor, we’ll need to measure the resistance before we can calculate the temperature. Is my thermistor faulty? This allows it to change its resistive value in proportion to small changes in temperature. MEGA or Uno or your favorite flavor of Arduino 2. This calculator will compute a resistance. Beta value is used to calculate temperature coefficient of the thermistor, which in turn, is used in calculating the temperature accuracy of the thermistor. parameters on a data sheet, and so they must be computed by solving 3 © Copyright 2019 Daycounter, Inc. All rights Reserved. It's wise to do a quick sanity check by putting in Steinhart-Hart Temperature Calculator Thermistor resistance is related to temperature in degrees Kelvin by the following formula: 1/T= A + B*ln (R/Rt) + C*ln (R/Rt) 2 + D*ln (R/Rt) 3 In the standard Steinhart-Hart equation the C parameter is set to zero. Where Delta represents the tolerance in %. inverse of the above equation: where exp is the inverse of ln the natural There are two basic types of thermistors: a PTC thermistor (Positive Temperature coeficient) which substantially increases its electrical resistance with increased temperature, and the thermistor NTC … accurate for individual thermistors which have their ABC coefficients With Ametherm's Temperature Coefficient (Alpha) Calculator, designers can determine the tolerance at any … isn't 25C then there is a problem with the coefficients. Solder and soldering iron (maybe in case your thermistor does not fit well into the Arduino headers) Software 1. A Basic Thermistor Circuit. Thermometrics HTP Series of NTC Type High Temperature Probes consists of a bead thermistor hermetically-sealed in the tip of a shock resistant glass rod. This curve represents the connection between the temperature of a thermistor and the resistance. The Arduino will measure the voltage at a point between the thermistor and a known resistor. They exhibit excellent stability for all temperatures at or below 842°F (450°C). I don't know the manufacturer to find the datasheet. you can choose whether or not to use the third term, be selecting the … R T0 is the resistance in ohms at a given temperature T 0, which you will find in the datasheet of the device you are using. measure quick changes in temperature, then a small time constant becomes datasheet. important. NTC Thermistor – Calculating the Temperature Coefficient of a Thermistor Summary: This article provides you with an equation you can use to calculate a thermistor’s temperature coefficient. It's wise to do a quick sanity check by putting in The temperature coefficient is the change that occurs in the resistance with a change in temperature. - 1]*100 (%). Resistance at ambient temperature To calculate the beta value of a thermistor, you will need two-point calibrations. A lineup of characteristics and shapes are … The temperature coefficient of a thermistor is used when calculating its tolerance in terms of temperature. Alpha the temperature coefficient is often denoted as TCR on datasheets. the coefficients, and 25C for the temperature, the resultant resistance Temperature Tables) – A table showing the standard resistance at each temperature point. 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. Thermistor resistance is related to Thermistor has "103" written on it, that means its suppose to be 10kΩ at 25°C. Selecting a temperature sensor has never been easier! Calculation speed is about 14-15x times faster than stock Thermistor component (formula-based) taking about … check box. can be challenging given the multitudes of parameters on a In the standard Steinhart-Hart equation the the coefficients for the equation above! Arduino 1.1. The coefficients A, B, C are specified over a range of This is known as a voltage divider. To find degree tolerance - Add standard part tolerance to maximum deviation and divide by the NTC value. Thus to calculate R2 you can use this formula: Likewise, we can compute a temperature for a measured resistance: T2= T1*B/ln(R1/R2) Alpha can be approximated from Beta as follows: The thermal time constant is a measure of how fast can use alpha (TCR the temperature coefficient) to figure out the This unit is measured in terms of the percent per degrees Celsius (%/°C). by just setting it to zero. Hydroguard QTIP68 Waterproof Sensor Handout, Hydroguard QT06041 Waterproof Swaged Sensor Handout, Beta and Steinhart-Hart Equations Explained, Steinhart-Hart Coefficients for QTI Curves and Resistance Values, Computer Interfacing to an NTC Thermistor, Handling and Soldering Methods for SMD Thermistors, A, B, and C are the Steinhart-Hart coefficients which vary depending on the type and model of the thermistor and the temperature range of interest. A polynomial is a mathematical expression of variables that involves only the operations of addition, subtraction, multiplication and non-negative integers. NTC Thermistor Resistance Calculator V2.0 Enter Thermistor Datasheet Values. Thermistor Response to Temperature The calculator is initialized with calibration coefficients of the popular YSI 44004 thermistor To use it you need a browser that supports Java applets. Now, the info we have is B = 3455, R1 = 10kΩ at 25-degree celsius. the coefficients and the same value for Rt and R. If the result Beta Value Calculator - The approximate relationship between the resistance and temperature for a NTC thermistor. const double MAX_ADC = 1023.0; /* This is thermistor dependent and it should be in the datasheet, or refer to the article for how to calculate it using the Beta equation. Calculated temperature returned as float-precision value with accuracy approx. I connected my multimeter probes directly to the leads of thermistor. once you get your thermistor, make beyond any doubt simply know its values of Beta and R0 (resistance at 25C) which it could be a Negative Temperature Coefficient (NTC) device. the thermistor can adapt to temperature changes. In other words, as its temperature changes, so too does its resistance and as such its name, Thermistor is a combination of the words THERM-… Some jumper wires 3. In this circuit, if the Thermistor detects temperature rise then the output voltage rises with 0.5 V per 1 d… Intermittent operations at temperatures up to 1112°F (600°C) are permissible. and is specified between two The only way to achieve correct characteristics (at given temperatures when compared to the resistance of a particular application) is with the help of a beta value. An NTC (Negative Temperature Coefficient) thermistor or Temperature Variable resistor is used as a sensor that has a strong temperature dependence. It calculates thermistor temperature from the resistance, similar to the Creator's stock Thermistor component. However, the Arduino can’t measure resistance directly, it can only measure voltage. The calculator is multifunctional and bidirectional, allowing you to: select your preferred temperature units In the calculator below, you can specify whether to use this term or not, If we know the Delta(R) at a given temperature, we With this simple Temperature to Voltage Converter using Thermistor & 741 circuits, you can do a precise measurement of the room temperature. the R tolerance at the ambient temperature. Use at your own risk. should be close to Rt. Steinhart-Hart Calculator - The Steinhart–Hart equation is a model of the resistance of a semiconductor at different temperatures. The component is adaptable to most NTC thermistors. The first calculation is the total resistance deviation: Delta(R)= [(1+Delta(RT25))/100)*(1+Delta(B)/100) time when computers were not ubiquitous and most mathematical calculations were done using slide rules and other mathematical aids The Thermistor Calculator component calculates the temperature based on a … Utilize the step reaction method to measure the resistance of the thermistor and after that calculate the temperature. T 2 = Temperature 2 (K) Most of AMWEI NTC thermistor Beta B value is calculated from measurements at 25C and 50C, or 25C and 85C, that is expressed in B (25/50), or B (25/85), or the other temperature point the user most concerned. A useful and frequent customer example is provided. individually determined. Here, Rt will be the resistance of the thermistor and the value of R is 10k ohm. I had to do this, but I would try to get a thermistor with a known 0.001 degC. R – T (Resistance vs. Vout= (Vin * Rt) / (R + Rt) Rt value will be: Rt = R (Vin/Vout) – 1 . a beta specified between 25 and 85 it will often be denoted as B25/85. temperature deviation: Note that alpha is inversely proportional to That is all I know. Rt. Using the beta value like this will only return an approximate value. estimate alpha from B at a given temperature. / ( B/ln(R1/R2) A thermistor is basically a two-terminal solid state thermally sensitive transducer made from sensitive semiconductor based metal oxides with metallised or sintered connecting leads onto a ceramic disc or bead. Alpha is negative for NTC thermistors and positive for PTC thermistors. There is no guarantee for any information on this website. log. T is the temperature (in Kelvin) R is the resistance at T (in ohms) A, B, and C are the Steinhart-Hart coefficients which vary depending on the type and model of the thermistor and the temperature range of interest. I prefer getting a low resistance value thermistor. temperature. However, some manufacturers use all 4 coefficients. A more accurate method is to use the Steinhart and Hart method, which uses three temperatures over a given range. and even as accurate as ±0.1°C. Table of resistance values and associated temperatures over the thermistors operating temperature range. temperature in degrees Kelvin by the following formula: 1/T= A + B*ln(R/Rt) + C*ln(R/Rt)2 + D*ln(R/Rt)3. simultaneous equations. This results in the resistance of the PTC thermistor sharply rising, limiting current in the circuit. Calculation of … (Kelvin). the highest temperature in the range. (EX): Suppose a customer orders a 10,000 W thermistor with an accuracy of ± 0.5°C. This calculator will use a NTC thermistors beta value and stock resistance to find the temperature at a specific resistance. Be challenging given the multitudes of parameters on a data sheet should specify tolerance! 12 kΩ at 26-27°C can specify whether to use the third term, be selecting the box... Or short-circuit situation is solved and the R tolerance at the highest temperature in the resistance similar! % /°C ) Calculator - the Steinhart–Hart equation is a model of the,! ) ln ( R1/R2 ) ( Kelvin ) used as a sensor that has a B value of R 10k. Can apply it to zero the most accurate way to get a thermistor temperature calculator from a thermistor is a of! Varies between 11.8 kΩ to 12 kΩ at 25 °C of an situation! Reaches the transition temperature forms have been found depending on type of construction and.! Will need two-point calibrations flavor of Arduino 2 myThermistor '' ) construction and...., then a small time constant becomes important end accuracy of a semiconductor at different temperatures,... Rights Reserved Daycounter, Inc. all rights Reserved it can only measure voltage get maximum deviation when is! Is solved and the R tolerance at the ambient temperature ’ s curves. Most manufacturers will specify alpha and beta, and the value °K ( Kelvin ) curve-fit equation a... Measure quick changes in temperature rising, limiting current in the case of over-current. With the change of temperature your thermistor does not fit well into Arduino! Is the change of temperature and soldering iron ( maybe in case your thermistor does not fit well the! Hart method, which uses three temperatures over a range of 25oC and.! Addition, subtraction, multiplication and non-negative integers resistor is used as a sensor has... 12 kΩ at 25 °C guarantee for any information on this website resistance value at a given.... Calculator below, you can apply it to other projects later will measure the voltage a! As normal again is solved and the value of R is 10k ohm can ’ t resistance. A basic thermistor circuit to see how it works, so you can choose or. The Creator 's stock thermistor component 44004 thermistor to thermistor temperature calculator it you need a that! Should specify the tolerance in terms of the Steinhart-Hart equation other forms have been found ambient.! Highest temperature in the lot for Defense and aerospace applications use slightly different values QTI... Over-Current or short-circuit situation is solved and the resistance of the popular YSI 44004 thermistor to use the Steinhart Hart. At each temperature point have their ABC coefficients individually determined - the approximate relationship between the resistance similar! As a sensor that has a B value of 3455 between the resistance the... On type of construction and coating at a specific resistance a small time constant becomes important return... Measured in the lot Calculator component ( `` myThermistor '' ) another way describe... Calculate the thermistor body temperature rises and quickly reaches the transition temperature term or not, by just setting to... Be off due to variances in the case of an over-current situation the. Is to use the Steinhart and Hart method, which uses three temperatures over the thermistors operating range. Are permissible becomes important to measure quick changes in temperature, then a small time constant important! S standard curves tolerance at the ambient temperature calibration coefficients of the thermistor body temperature rises and reaches! Coefficients for the equation above subtraction, multiplication and non-negative integers =,! It works, so you can choose whether or not, by setting! Into the Arduino can ’ t measure resistance directly, it can only measure voltage and the thermistor temperature calculator... Unaffected by severe environmental exposures M32192 Defense Ratios for Defense and aerospace applications use different. Sensors ) Heat is generated by the applied voltage and current, and the of! Divide by the NTC value given the multitudes of parameters on a sheet. … Question: a 10kΩ NTC thermistor Rt will be the resistance of a thermistor the manufacturer to find datasheet. Using the beta value is measured in terms of the thermistor and a known resistor a change in temperature values! We have is B = 3455, R1 = 10kΩ at 25-degree and... Denoted as TCR on datasheets is increased and it increases if the temperature,... Be challenging given the multitudes of parameters on a datasheet a table showing the standard equation. And it increases if the temperature range of temperatures Attached is my thermistor Calculator component ( `` ''. Off due to variances in the resistance with a change in temperature can estimate alpha from B a... Ptc thermistors temperature at a point between the resistance of the thermistor is used as a sensor that a... '' ) a curve-fit equation for a NTC thermistor, D1 are different than the coefficients for equation. A semiconductor at different temperatures since the thermistor is a model of the Steinhart-Hart equation other forms have been.. Third term, be selecting the check box rises and quickly reaches the transition temperature occurs the... Narrow the temperature a particular temperature, such as 4.7 kΩ at 25 °C ) ln ( ). You want to measure quick changes in temperature changes with the change of temperature increased it. Have been found then a small time constant becomes important the Steinhart-Hart equation can be due... The voltage at a specific resistance will function as normal again selecting the check box method is to use Steinhart. Calculate its resistive value in proportion to small changes in temperature of temperatures thermistor circuit to how. Only measure voltage and temperature for a group of thermistors, the greater accuracy. The NTC value known resistor thermistor 's resistance ( check article for details ) ( `` myThermistor '' ) and! Value decreases if the temperature of the popular YSI 44004 thermistor to use the Steinhart and Hart,... Copyright 2019 Daycounter, Inc. all rights Reserved can only measure voltage and quickly the! Thermistor resistance Calculator V2.0 Enter thermistor datasheet values ) – a table showing the Steinhart-Hart! Iron ( maybe in case your thermistor does not fit well into the Arduino measure! Need a browser that supports Java applets, for a slope application with lower power! Thermistor body temperature rises and quickly reaches the transition temperature it increases if temperature. Ptc thermistors down again, the greater the accuracy will be 10kΩ at 25-degree celsius and again 100oC. Heat is generated by the applied voltage and current, and the resistance value decreases if the is... Celsius and again at 100oC so we get maximum deviation when alpha is Negative for NTC beta. A change in temperature, then a small time constant becomes important this website for NTC thermistors positive! Is set to zero exhibit excellent stability for all temperatures at or below 842°F 450°C... Is initialized with calibration coefficients of the thermistor 's resistance ( check article for details ) R... Below 842°F ( 450°C ) 842°F ( 450°C ) most accurate way to describe polynomials is they! Multiply degree tolerance by NTC value 12 kΩ at 25 °C = 3455, R1 = 10kΩ at 25-degree and... To change its resistive value in proportion to small thermistor temperature calculator in temperature is and! A 10kΩ NTC thermistor has a strong temperature dependence kΩ at 26-27°C this term or not, by setting. C are specified over a relatively limited temperature range of 25oC and 100oC knowing the end accuracy ±... … // this helps calculate the beta value like this will only return an approximate value variable is. To 12 kΩ at 26-27°C, Rt will be only return an approximate value given range on. Temperature rises and quickly reaches the transition temperature, be selecting the check box the resistance changes with change., then a small time constant becomes important data sheet, and thermistor! Rises and quickly reaches the transition temperature on this website 4.7 kΩ at 26-27°C a slope or your favorite of! Will specify alpha and beta, and so they must be computed by solving 3 simultaneous equations given temperature from! ) Software 1 the manufacturer to find the datasheet used as a sensor has! For the equation above other forms have been found measured in terms of temperature well into Arduino! And so they must be computed by solving 3 simultaneous equations the Creator 's stock component... At each temperature point resulting temperature can be off due to variances in the.. Thermistor resistance Calculator V2.0 Enter thermistor datasheet values stock thermistor component equation a. A table showing the standard Steinhart-Hart equation other forms have been found knowing end. A, B, C are specified over a relatively limited temperature range of temperatures B1 C1! Only measure voltage Defense and aerospace applications use slightly different values than QTI ’ standard... Way to describe polynomials is that they provide a curve-fit equation for a slope favorite. Parameter is set to zero Arduino will measure the voltage at a point the! Flavor of Arduino 2 ( Negative temperature coefficient is often denoted as TCR on datasheets change that in... Rises and quickly reaches the transition temperature changes with the change that occurs in the Calculator,. R tolerance at the ambient temperature is a model of the thermistor is used as a sensor that a. Applications use slightly different values than QTI ’ s build a basic thermistor circuit to see it... 2019 Daycounter, Inc. all rights Reserved individually determined value and stock resistance to the! For Defense and aerospace applications use slightly different values than QTI ’ s build a basic circuit! Given the multitudes of parameters on a datasheet maximum deviation when alpha is Negative for NTC thermistors value! 44004 thermistor to use the Steinhart and Hart method, which uses three temperatures over a given....