Modifications

One difficulty in using them is that the voltage to be measured is very small, with changes of about 50 uV per °C (a uV is 1/1000000 Volts). While it is possible to read these voltages using a clean power supply and nice op-amps, there are other complications such as a non-linear response (its not always 50uV/°C) and cold-temperature compensation (the effect measured is only a differential and there must be a reference, just as ground is a reference for voltage). For that reason, we suggest only using an interface chip that will do the heavy lifting for you, allow you to easily integrate the sensor without as much pain. In this tutorial we will use a MAX6675 K-thermocouple interface chip which doesn't even require an ADC, spitting out a nice digital data signal of the temperature.

One difficulty in using them is that the voltage to be measured is very small, with changes of about 50 uV per °C (a uV is 1/1000000 Volts). While it is possible to read these voltages using a clean power supply and nice op-amps, there are other complications such as a non-linear response (its not always 50uV/°C) and cold-temperature compensation (the effect measured is only a differential and there must be a reference, just as ground is a reference for voltage). For that reason, we suggest only using an interface chip that will do the heavy lifting for you, allow you to easily integrate the sensor without as much pain. In this tutorial we will use a MAX6675 K-thermocouple interface chip which doesn't even require an ADC, spitting out a nice digital data signal of the temperature.

== Informations techniques ===

== Informations techniques ==

Voici quelques informations relatives au thermocouple de type-K

Voici quelques informations relatives au thermocouple de type-K

* Tension de sortie: -6 à +20mV

* Tension de sortie: -6 à +20mV

* Précision: +-2°C

* Précision: +-2°C

* '''Nécessite un amplificateur''' tel que le MAX31855

* [http://mchobby.be/PrestaShop/product.php?id_product=302 '''Nécessite un amplificateur''' tel que le MAX31855]

    Interface: MAX6675 (discontinued) MAX31855, or AD595 (analog)

* Interface: MAX6675 (''interrompu''), ou MAX31855 (numérique), ou AD595 (analogique)

    K Thermocouple Datasheet

* [http://mchobby.be/data-files/datasheet/kthermotable.pdf Fiche technique du Thermocouple Type-K] (pdf)

* [http://mchobby.be/data-files/datasheet/MAX31855.pdf Fiche technique du MAX31855] (pdf)

    MAX31855 Datasheet

{{Thermocouple-TRAILER}}

{{Thermocouple-TRAILER}}