Calibration table system for NTC temperatur sensors

Here is a picture of a calibration system for NTCs I have made.

Items used:

• Arduino
• AD595 K-type temperature sensor (@watterrot)
• K-type sensor
• Breadboard
• Breadboard wires
• LCD Display
• NTC sensor
• Insulation material (Rockwool, Glasswool, cork, and more can be used)
• Kapton tape
• Constantan wire
• A piece of aluminium
• Thermal paste

Other links:

Thermistor (NTC) info and Thermistor tables at RepRap.org

The Arduino sketch used packed in a zip file.

Update:

Here is the table that came out of the experiment

The first column is RAW data, that is the value read from the analog port,

 the second column is temperature.

Raw numbers for temperatures above 280-290*C are not usefull, but that was to be expected, at the NTC is only supposed to go until 300*C

#define NUMTEMPS 72
short temptable[NUMTEMPS][2] = {
   {7,355},
   {7,350},
   {8,345},
   {8,340},
   {9,335},
   {10,330},
   {10,325},
   {11,320},
   {12,315},
   {13,310},
   {13,305},
   {14,300},
   {15,295},
   {17,290},
   {18,285},
   {20,280},
   {21,275},
   {23,270},
   {25,265},
   {27,260},
   {29,255},
   {32,250},
   {34,245},
   {37,240},
   {41,235},
   {45,230},
   {49,225},
   {54,220},
   {59,215},
   {64,210},
   {71,205},
   {78,200},
   {85,195},
   {95,190},
   {105,185},
   {116,180},
   {129,175},
   {142,170},
   {158,165},
   {174,160},
   {193,155},
   {213,150},
   {238,145},
   {271,140},
   {295,135},
   {322,130},
   {354,125},
   {385,120},
   {418,115},
   {453,110},
   {490,105},
   {529,100},
   {566,95},
   {605,90},
   {643,85},
   {681,80},
   {717,75},
   {752,70},
   {782,65},
   {814,60},
   {838,55},
   {863,50},
   {883,45},
   {904,40},
   {919,35},
   {934,30},
   {946,25},
   {958,20},
   {966,15},
   {974,10},
   {983,5},
   {992,0}
};

So for practical use, I would trim some of the rows out. 

The following table is probably more useful with a RepRap.

#define NUMTEMPS 30
short temptable[NUMTEMPS][2] = {
   {7,355},
   {14,300},
   {20,280},
   {27,260},
   {37,240},
   {54,220},
   {59,215},
   {64,210},
   {71,205},
   {78,200},
   {85,195},
   {95,190},
   {105,185},
   {116,180},
   {129,175},
   {142,170},
   {158,165},
   {174,160},
   {193,155},
   {213,150},
   {238,145},
   {271,140},
   {385,120},
   {529,100},
   {681,80},
   {814,60},
   {904,40},
   {946,25},
   {974,10},
   {992,0}
};

Other pictures of interest:

This is what temperatures of at least 350*C will do to kapton tape. 

The constantan wire was probably a slight bit warmer than the temperature at the thermistor/K-type sensor, to compensate for some heat loss through the insulation.

This is what happens to Glasswool at 315*C.

.

On the right is what fresh Glasswool looks like, on the left is what it looks like after exposed to 315*C. From the amount of smoke coming from the test bed setup, I did not dare go any higher with Glasswool.

The scorching is about 5mm deep

At 350*C even Rockwool suffers some discoloration, but the smoke was not near as bad.

The kapton tape from the Rockwool pad, suffered some wrinkling in the center, but was not burnt like the kapton that had direct contact with the heating wire.

I really love that kapton tape. It my new favorite kind of tape.

Closeup of the Vero board with the RepRap style NTC sensing, and the MosFET on/off controller.