Thermocouple technology makes these digital models the fastest on the market, showing temperature readings in 3-6 seconds, with high accuracy and a wide temperature range. Thermocouple technology. The thermocouple is a device that generates electricity when heat is applied to its tip. It consists of two different types of metal wires that are both electrical conductors, joined together at one end and connected to a voltage-measuring device at the other end. When the junction of the two metals is heated or cooled, a voltage is created that can be correlated to temperature. Thermocouples are available in different combinations of metals or calibrations. The most common calibrations are J, K, T, and E, each of which measures a different temperature range. The maximum temperature changes with the diameter of the wire used.