Optional Input Filtering and Broken Thermocouple Detection

To reduce noise, you can build a simple RC lowpass filter in the breadboard area.

Build broken-thermocouple-detection circuitry by connecting a high-value resistor between the positive input and +5 V. The value of this resistor is relatively unimportant; a few megaohms or more works fine. You can detect an open or defective thermocouple with a high-value resistor. If the thermocouple opens, the voltage measured across the input terminals rises to +5 V, a value much larger than any legitimate thermocouple voltage.