Trouble with 31855K Thermocouple

I am new to Arduino and just received my 31855 board and Set it up as described here

The output I am getting is attached. The internal temp reads OK. The sensor is at room temperature. There are 3 problems

  1. readings are negative,
  2. reading are unstable
  3. readings are inaccurate

I can’t figure out what I have done wrong. I have checked my connections.



Just remember at normal temperatures the red wire is [u]negative[/u] on most thermocouple types, type K is red and yellow. Don't know if that helps but its something to check first.

Thanks for your reply. I have a green and a white wire. I have tried connecting both ways but the three issues I mentioned remain the same. Only difference is that the temperature starts to decrease when heated on reversing the connections.

I have seen people recommending 'grounding' the Arduino to help with the fluctuation but I don't understand how I would go about doing that.

OK, I got it to work! Added a 0.01uF capacitor across the thermocouple connectors and all the problems vanished.