Self-adjusting hinge for telephone bell striker - eliminates microphonic effects at electrical contacts by use of flexible connection

摘要

The striker (clapper 18, arm 35) lies under the gong of the telephone bell, with its electrical contacts (26) resting against fixed contacts at either end of the solenoid. Thermal expansion or contraction of the metal yoke (25) that carries the moving contacts can lead to poor electrical connections and so to microphonic effects. An unusually flexible hinge (29) is used with the striker, in the form of a long hoop (30) of flat material. The striker is joined (28, 32) to the middle of one side of the loop and the fixing bracket (33, 34) to the middle of the other one. The hinge is self-adjusting and equalises the pressure on the two electrical contacts (26).