Miniature snap-action switch

– Invented by Phillip Kenneth McGall in 1932 in Freeport, Illinois, patent 1,960,020
– McGall was an employee of the Burgess Battery Company at the time
– In 1937, W.B. Schulte, McGall’s employer, started the company MICRO SWITCH
– The company and the Micro Switch trademark has been owned by Honeywell Sensing and Control since 1950
– The name has become a generic trademark for any snap-action switch

Construction and operation
– Internally, there are two conductive springs in a micro switch
– A long flat spring is hinged at one end of the switch and has electrical contacts on the other
– A small curved spring, preloaded during assembly, is connected between the flat spring near the contacts and a fulcrum
– An actuator nub presses on the flat spring near its hinge point
– The over-center action of the springs produces a distinctive clicking sound and a crisp feel

– Micro switches are used when a low operating force with a clearly defined action is needed
– They are also used when long-term reliability is needed due to the internal mechanism and the independence of the closing force on the switch contacts from the operating force
– Common applications include door interlocks on microwave ovens, safety switches in elevators, arcade buttons, and detecting faults in photocopiers
– Micro switches are used in tamper switches on gate valves in fire sprinkler systems and water pipe systems
– They are widely used in appliances, machinery, industrial controls, vehicles, and other places for control of electrical circuits

Related concepts
– Mercury switch
Reed switch

– Shouer, Dick (1 March 2015). Honeywell History. Honeywell.
– MICRO SWITCH Timeline – 1950s. Archived from the original on February 9, 2011. Retrieved 2020-01-13.
– Piter, Tiago. Micro switch. Archived from the original on 2020-08-07. Retrieved 2020-10-07.Sources: