Abstract: The invention is an improvement in a gun-like device (often referred to as a "heat gun") emitting heated air at a variable temperature which can be selected by the user. The potentiometer used to set the desired air temperature is connected to an integrated circuit (rather than to an amplifier used as a variable gain element) and is used in such a way that the percentage of total potentiometer resistance in a portion of the circuit, rather than the actual potentiometer resistance value, regulates temperature. Low-cost, smaller potentiometers having a relatively "loose" tolerance can thereby be used. The new regulator also includes a novel circuit for shutting down the heat gun in the event of an open thermocouple and a novel circuit for essentially eliminating the undesirable subtractive effect of cold junction circuit board voltages on the hot junction voltage produced by the thermocouple.