How to Use Aluminum & Copper to Make a Thermocouple

Connect an aluminum wire to one post of an ammeter, a copper wire to the other post and twist the distal ends of the wires together. The twisted ends of the wires form the temperature probe. Place the temperature probe at the temperature source you want to measure. Read the ammeter and correlate the reading to the temperature on a chart. The housing for the assembly depends entirely on the use to which you will be putting the thermocouple.

Separate the temperature probe from the ammeter with whatever you need for the temperatures you will be measuring. For the extremely tight places in small electronic devices, engineers run micro-wires of aluminum and copper wires through syringe needles to make small thermocouples. For use around the laboratory, thermocouples use wires run through a pencil-sized rod. For measuring the temperature in volcanoes, the two wires are run down along a metal cable to support the weight of the 1,000-foot wires needed for the job.

Replace the ammeter with a special, more expensive meter built to read the current level from a aluminum-copper thermocouple and give a readout in degrees. If you use the cheaper ammeter, you will have to keep a conversion chart -- available in physics books and online -- to convert from amps to degrees every time you use the thermocouple.