Hey, been a while since I was last on here.
Anyway, I'd like to make a Thermometer which has K Type thermocouple inputs.
I've bolded the main questions which I would like answering.
I've recently been looking at the process of reading temperatures with K Type thermocouples and I found it to be the following:
1) Calculate the temperature of the "Ice Point Compensation" thermistor.
2) Use a K Type lookup table to calculate the equivalent voltage for this Ice Point temperature.
3) Get the voltage of the K Type and subtract (Or add ?) the compensation voltage.
4) Use the K Type lookup table to convert this new voltage to the temperature of the probe.
Firstly, is this process correct ?
Secondly I don't quite understand the tables.
Here's a table that I found:
https://www.instrumentation-central.com/TechNotes/TypeKTableC.pdf
From what I understand the bold column down the left in the temperature in degrees C and the values in the middle of the table are the corresponding voltages of the thermocouple in mv, assuming an Ice Point of 0C.
However I don't understand what the "0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10" headings are across the tol of the table, what are these and how do they affect me ?
Thirdly are there any formulas for conversion of K Type themperatures and voltages which can easily be done on a PIC18f (In C) ? There must be formulars for conversions both ways, I.e. Temperature to Voltage and voltage to Temperature.
Finally I've been looking at an opamp to use to build the differential amplifier for the thermocouple it's self. I've just got a sample of
TC913A from Microchip. (Datasheet link) Would these be suitable ? What other alternatives are there which would be better, or would these ones be more than suitable ?
Thank you very much for any help,
-Andrew.