Help with K type thermocouple and AD8495

Discussion in 'The Projects Forum' started by FardinBiper, Oct 24, 2012.

  1. FardinBiper

    Thread Starter New Member

    Aug 21, 2012
    11
    0
    Hello,

    I made thermocouple amplifier circuit with the analog devices AD8495.
    http://www.analog.com/static/imported-files/data_sheets/AD8494_8495_8496_8497.pdf
    There is an application note that tells you how to configure the circuit (figure 6).
    http://www.analog.com/library/analogDialogue/archives/44-10/thermocouple.pdf
    I made the circuit exactly similar to the app note, however it is giving me incorrect data. The thermocouple sensor is working fine and it can be read by a handheld temperature reader.
    On the datasheet it says that if you short out and ground the thermocouple pins, you can read the internal temperature sensor. The goods news is I can do this and the data is accurate.
    However when I connect the K type thermocouple I get 4.95V out of the temperature amp which corresponds to above 900 degC.
    Please help in way to troubleshoot this circuit.
    Thanks
     
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