simple circuit reverse engineering

Hello jremington,
thanks for your reply. What I am doing is an automatinc welding machine. In order to know when to start the welding process I need to know when the part reaches the set temperature. The reason I need to use that particular sensor is that I have 5 of them available, taken from old welding machines and doing that exact job of sensing the welding temperature. I am by no means a "novice" with arduino and programming, but i can only define myself an "hobbyist" regarding electronic, and I never ever used SMD components, that is why I am asking for help.