EEVblog #419 – Thermocouple TutorialPosted on February 3rd, 2013
18 comments Everything you need to know about how Thermocouples
work. K type thermocouples, the Seebeck effect, the Seebeck
coefficient, and cold junction compensation. Along with some
practical measurements with a multimeter to demonstrate the
effect. Seebeck effect on a single conductor Forum Topic HERE
The MAX31855 part from Maxim is a nice Cold-Junction Compensated
Thermocouple-to-Digital Converter. This chip came out not too
long ago to replace Maxim’s MAX6675 chip. The MAX31855 has
14-Bit/0.25 deg. C resolution. There are different version chips
for K, J, N, T, S, R, & E-type junctions. The interface is half
duplex SPI. The MAX31855 comes in a friendly 8-SOIC package.
Mouser lists them for $7.75 USD each in unit quantity. There’s a
Maxim eval board for $110 bucks. Adafruit has a relatively cheap
($17.50) breakout board for the MAX31855 but the schematic is
not readily available (I asked – they ignored). Adafruit also
sells a K-type glass b