NTC / CTN 10K Thermistor, GT103J1K

Measure temperature up to 500°C with thermistor

The thermistor is an electronic component where the electrical resistance varies with temperature. Being one of the most widely used components in electronics, the thermistor comes in a variety of different forms.

The advantage of the thermistor is its resistance greatly varying within the temperature range. It is therefore easier to perform a reading on an analog input of a microcontroller. The accuracy of a thermistor is generally about 1% (offering an accuracy of around 0.25 ° C).

On the other hand, reading the temperature requires more processing on the microcontroller side since the thermistor is used as a resistance bridge element. It will be necessary to measure the tension on a part of the bridge and to interpret it to determine the temperature.
The thermistor also has a thermal time constant from 2 seconds (for the best) to 15 seconds. it is the time necessary to have a homogeneous temperature at the heart of the thermistor and thus ensure a correct measurement of the temperature (if it fluctuates).

There are two types of thermistor: NTCs with negative temperature coefficient (case of this productl) and PTC positive temperature coefficient.

The model offered here has mostly been made popular by the use of 3D printers where the high temperature of the print head must be continuously monitored. This NTC is able to measure a temperature from -55 ° C to + 500 ° C, the thermistor is trapped in a glass bead from which two copper strands emerge allowing connection to the reading circuitery.

This is not a vague copy from China but a 10 KOHms GT103J1K model from LittleFuse whose production cycle is perfectly controlled. The thermal time constant is 2.5sec, therefore very reactive in the field of thermistors.
So no surprise in terms of quality and repeatability. The reliability of supply is also the reason for its higher price.

How to use

To use this NYC, you will have to place a 4.7K Ohms resistor inline with the NTC to create a voltage divider bridge.

GND --> NTC <---> 4.7K <--- VCC

The voltage measurement (so the temperature) is done over the NTC. When the temperature increase, the Rntc falls.

Adafruit did published a great thermistor tutorial with application notes and temperature calculation based on the Steinhart-Hart equation.

Technical details

• Temperature range: -55 to 300°C
• Resistance @ 25°C: 10 KOhms
• Resistance Tolerance: 10% @ 25°C
• R-T Curve: J
• Temp Coef: -4.4 %/°C @25°C
• Beta (K) 25-85°C: 3977
• Dissipation Constant: 0.45 mW/°C
• Thermal Time Constant: 2.5 sec (max, air libre / still air)