Earthquake alarm appts. including mercury switch - has suspended metal chain which is moved by vibration to complete bell circuit

摘要

An insulating housing (2) has an opening for sound emission It encloses sound generating components, which may comprise chime plates mounted on projections of the housing. The chime plates (7, 8) are rung by striker pins (9, 10)actuated by solenoid and having a biasing spring to return them to the rest position. The solenoid coil (12) is actuated by a voltage source which may conveniently be a group of primary cells (14). A rocking mercury switch (24) connected to one striker pin (9) is included for continuous operation. Suspended from a metal bracket mounted on the housing is a metal chain (17). This passes through a hole (19) in a second metal bracket (20). Connections to the two metal brackets complete an electrical circuit. The chain is normally isolated from the second bracket, but, in the event of an earthquake, it touches the bracket completing the circuit and actuating the alarm.