An infinite switch or infinite controller is a type of switch that allows variable power output and is so called because its average output is infinitely variable rather than being limited to a few switched levels. They utilize a bi-metallic strip conductive connection across terminals that disconnects with increased temperature. As current passes through the bimetal connection, it will heat and deform, breaking the connection and turning off the power. After a short time, the bimetal will cool and reconnect. Therefore, infinite switches vary the average power delivered to a device by oscillating quickly between on and off states. They may be used for situations that are not sensitive to such changes, such as the resistive heating elements in electric stoves and kilns.
Disadvantages of the high-speed mechanical switching include erosion of the switch contacts by arcing and generation of radio-frequency interference and a general unsuitability for handling high powers and inductive loads.