Thermocouple vs Thermistor

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Test comparing Thermocouple vs Thermistor

I originally wanted to just calibrate the thermistor table I used in my FW, since I remember that Camiel from Mendel-parts was moaning that his table was horrible and it affected his prints, I now just guess that his table wasn't made for his thermistor. I used one generated exactly for my thermistor by createTemperatureLookup.py from SVN. So I created a fake heater with both a Thermocouple and a Thermistor and wrote a small sketch in Arduino to generate the table, BUT I did want to simply see how imprecise it was. I was shocked that both readings were pretty close. Actually, the biggest deviation was 3°C. You can see the graphs below and also download the Arduino sketch and sample data.

My verdict, is that both technologies are good for heaters and heatbeds, the precision is mainly affected by the mounting on the heater. Also be careful to use precision resistors for thermistor circuits, that's all :-)

For more details see the following pages here for RepRap use of Thermistors and Thermocouples. There is abundant theory on the Wikipedia pages for [thermistors] and [thermocouples].

CompareGraph.jpg DeviationGraph.jpg

Files

FILE ID# TYPE DESCRIPTION AVAILABLE FORMATS CREATED/RESERVED BY
Arduino code and data PDE CSV XLS Data .zip --Prusajr 12:08, February 5, 2011 (UTC)