They come in two types&colon; hot cathode and cold cathode. Neon lights are a type of cold cathode gas-discharge light. Common examples are the Hot and Cold Cathode gauges. Most ion gauges come in two types&colon; hot cathode and cold cathode. Both hot cathode and cold cathode type devices are encountered. His early experiments were with Crookes tubes, a cold cathode electrical discharge tube. This is in contrast to a cold cathode, which does not have a heating element. Cold cathode lamps have electrodes that operate at room temperature. The cold cathode system was installed in a number of gold mines and worked reliably. A cold cathode is a cathode that is not electrically heated by a filament.