electric bell

An electric bell is an audible warning device in which a small clapper is made to vibrate rapidly against a resonant metal gong. This is usually archived by using a direct-current electromagnet to attract the clapper arm toward the gong, while a make-and-break contact cuts off the current just before the clapper strikes, so that the spring-loaded clapper arm recoils – remaking the circuit and commencing another cycle. In the single-action bell, there is no repeater mechanism.