How Easy Is It To Use A Thermistor?!

About the project

Thermistor as thermometer.

Project info

Difficulty: Moderate

Platforms: Arduino

Estimated time: 1 hour

License: GNU General Public License, version 3 or later (GPL3+)

Items used in this project

Hardware components

10 Jumper Wires 150mm 10 Jumper Wires 150mm x 1
Genuino Uno Rev3 Genuino Uno Rev3 x 1
Resistor Network - 10k Ohm (6-pin Bussed) Resistor Network - 10k Ohm (6-pin Bussed) x 1
Thermistor 10k Thermistor 10k x 1
Tiny Breadboard Tiny Breadboard x 1

Software apps and online services

Arduino Web Editor Arduino Web Editor
Arduino IDE Arduino IDE

Story

How easy is it to use a thermistor?!

In this article I will explain how to use a thermistor. First of all, what is it a Thermistor? A thermistor is a type of resistor whose resistance is dependent on temperature. There are two opposite types of thermistor:

  • PTC (Positve Temperature Coefficent), resistance increases as temperature rises
  • NTC (Negative Temperature Coefficent), resistance decreases as temperature rises

In this case I use NTC.

A little bit of math.

To calculate the thermistor resistance using a simple formula called equation with parameter B (with only NTC termistor).

Where:

  • e is the base of natural logarithm
  • R0 is the resistance of the thermistor measured at the temperature T0
  • B is a constant coefficient that depends on the characteristics of the material, it is a constant expressed in K, and its value is indicated by the manufacturers on the technical sheets

To calculate the temperature we need know the resistance RT using the Ohm's laws.

This is a schematic version of circuit.

RT = VRT / (VR/R)

Now we have all the data to calculate the temperature.

Remember to convert all parameters (for example T0) to Kelvin before the calculations, and also the result is in Kelvin.

This is the result.

Schematics, diagrams and documents

termistore_bb.jpg

termistore_schem.jpg

Code

Thermistor

Credits

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