Thermistors

RepRap Thermistors

Each thermistor has a variety of special values such as Beta and Rz value. A variety of thermistors you may encounter when building a RepRap are listed below, along with the appropriate information.

RRRF 100K Thermistor

• Beta: 3960
• Rz: 337254
• datasheet

Lookup Table For Temperature Sensor v1.x

• R1 = 0
• R2 = 4700

#define NUMTEMPS  20
short temptable[NUMTEMPS][2] = {
// { adc ,  temp }
   { 1 ,  929 } ,
   { 54 ,  266 } ,
   { 107 ,  217 } ,
   { 160 ,  190 } ,
   { 213 ,  172 } ,
   { 266 ,  158 } ,
   { 319 ,  146 } ,
   { 372 ,  136 } ,
   { 425 ,  127 } ,
   { 478 ,  119 } ,
   { 531 ,  111 } ,
   { 584 ,  103 } ,
   { 637 ,  96 } ,
   { 690 ,  88 } ,
   { 743 ,  80 } ,
   { 796 ,  71 } ,
   { 849 ,  62 } ,
   { 902 ,  50 } ,
   { 955 ,  34 } ,
   { 1008 ,  2 }
};

RRRF 10K Thermistor

• Beta: 3964
• Rz: 29000
• datasheet

Lookup Table For Temperature Sensor v1.x

• R1 = 680
• R2 = 1600

#define NUMTEMPS  22
short temptable[NUMTEMPS][2] = {
// { adc ,  temp }
   { 1 ,  608 } ,
   { 60 ,  176 } ,
   { 70 ,  166 } ,
   { 80 ,  157 } ,
   { 90 ,  150 } ,
   { 100 ,  143 } ,
   { 110 ,  137 } ,
   { 120 ,  131 } ,
   { 130 ,  125 } ,
   { 140 ,  120 } ,
   { 150 ,  115 } ,
   { 160 ,  110 } ,
   { 170 ,  105 } ,
   { 180 ,  100 } ,
   { 190 ,  95 } ,
   { 200 ,  91 } ,
   { 210 ,  86 } ,
   { 220 ,  81 } ,
   { 230 ,  75 } ,
   { 240 ,  70 } ,
   { 250 ,  64 } ,
   { 300 ,  4 }
};

RS 10K Thermistor

• Beta: 3480
• Rz: 29000
• datasheet

Lookup Table For Temperature Sensor v1.x

• R1 = 680
• R2 = 1600

#define NUMTEMPS  20
short temptable[NUMTEMPS][2] = {
// { adc ,  temp }
   { 1 ,  922 } ,
   { 16 ,  333 } ,
   { 31 ,  266 } ,
   { 46 ,  231 } ,
   { 61 ,  207 } ,
   { 76 ,  189 } ,
   { 91 ,  174 } ,
   { 106 ,  161 } ,
   { 121 ,  150 } ,
   { 136 ,  140 } ,
   { 151 ,  131 } ,
   { 166 ,  122 } ,
   { 181 ,  113 } ,
   { 196 ,  104 } ,
   { 211 ,  95 } ,
   { 226 ,  86 } ,
   { 241 ,  76 } ,
   { 256 ,  65 } ,
   { 271 ,  52 } ,
   { 286 ,  34 }
};

Thermistor Calculations

If you are using a non-standard thermistor, or you simply want more information on how they work, check these pages out.

Calculating Thermistor Beta

This is how you calculate the Beta value for a thermistor. You'll need this value if you plan on using a non-standard thermistor for sure.

Read more here

Calculating PIC Temperatures

The PIC uses a capacitor and charges it through the thermistor. It sends the temperature back to the host as a timer reading. This page describes how it is calculated and how to choose the right capacitor.

Read more here
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