J-type thermocouple Definition: A thermocouple best suited for measurements in the 0 to 480 degree © range. The positive conductor is made of iron, and the negative conductor is made of constantan. May i put my two cents in here ? mrtrhs, how about a radioshack thermistor? i realize that you may not have a "shack" around the corner ,but the thermistor ,in my opinion , is the way to go. You could set up a voltage divider using 5V as a supply voltage. Just a suggestion.. ;D Oh ... What temperature range are u thinking of measuring?