Simple Thermocouple Sketch Gone Wrong

Hey guys new the wonderful world of Arduino, I am having trouble with a simple setup to test my Type K thermocouple and AD595 amplifier.

With my voltmeter I am reading a +/-10uV fluctuations due to temperature plus a reading of 270mV which according to the tables is around 27 C. The AD595 and thermocouple are operating as they should.

I have tried a few different setups on the arduino end:

1.) Analog input with no external voltage reference tied to AREF. 2.) Analog input with external voltage (5.54V) to AREF. I followed the reference usage directions:

  • Defined my analogReference(EXTERNAL);
  • Included: #define ANALOG_VOTLAGE_REFERENCE 5.5 3.) In either case I get similar results:

Either the readout on the serial monitor is 0.00 with the reference tied in, or it cycles wildly through up to 1023 and then back to zero.

What I am not understanding is how I can read the correct values at the analog input terminal but even when I just print the raw serial data using Serial.Print(analogRead(0)); I get either zero or wild cycling. Shouldn't I see 270 or so if I just printed the raw AI value?????

Here is the example test sketch PLEASE HELP I'm drowing over here, and I know I am missing something really simple.

float myVal; //#define ANALOG_VOTLAGE_REFERENCE 5.5

void setup() { // analogReference(EXTERNAL); Serial.begin(9600);


void loop() { myVal = analogRead(2); Serial.print(myVal); // Serial.println((5.54 * myVal) /1024);// just change 5 to 4.87 delay(1000); }


Some links to the hardware you have would be useful. So would a schematic or picture of how it is all connected. The grounds are all connected, right?


Type K Thermocouple:

I followed the schematic from here:

Grounds are all connected as shown.

I am using the 328 arduino

No fret figured it out, I feel dumber and smarter at the same time, thanks though.

What was the solution? It may help others in the future :)