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Topic: new thermocouple interface: MAX31855 (Read 16379 times) previous topic - next topic


Sep 16, 2011, 04:18 pm Last Edit: Sep 16, 2011, 07:59 pm by EmilyJane Reason: 1


I'm using MAX31855 tipe K for measuring temperature. I can get
right value if the TC wire is short only, for example 30 cm in my
case. I start getting wrong measurement if I use long wire, for
example 4 meters. What do I do wrong?

Thank you.

What are you using for extension wire? And how "wrong" are your measurements?


The uncalibrated accuracy on the MAX31855 should around +-2degC. The repeatability should be
a bit better. When I did a quick test nn my new board I was getting +-2degC and a repeatability
of around +-0.25degC. I will doing some tests over the next few weeks.

I added two channels to the board and some terminal blocks for ADC channels, I2C and SPI
ports. I also added a 5V boost converter.

I will have the schematic and documentation done in the next few weeks.
Preliminary information is at http://tinyurl.com/3vuatby
(* jcl *)

Are we close to a breakout board for the Arduino yet? I've been looking at the MAX31855 as well since I need a J type thermocouple connection.

Would I be able to connect a Logic Level converter http://www.sparkfun.com/products/8745 to the Adafruit's MAX6675 breakout board (https://www.adafruit.com/products/269) in order to use the 3.3V MAX 31855?


The wiblocks ZB2 TC interface board will work with J type thermocouples
if the MAX31855 is changed to a MAX31855J and the input connectors
are changed to J-type.

(* jcl *)

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