Recent Developments in Bell System Relays - Particularly Sealed Contact and Miniature Relays

An important article entitled ''Relays in the Bell System" was published1 in the B.S.T.J. in 1924. This was a comprehensive article on relays which were then in use in the Bell System, and it gave some information on typical applications. Since that time, a few articles have appeared in the B.S.T.J. covering relays, particularly the article 2 in 1952 describing the general purpose wire spring relay. This is the most widely used relay in Bell System equipment at the present time. In addition there have been several comprehensive publications on the design of relays3-4 and several new forms of the wire spring relay, namely the "two-in-one" relay 5 and a magnetic latching form of this device. Miniature wire spring relays have been and are being studied. * In this paper, this is a remanent material of suitable coercive force range, generally intermediate between the common permanent magnets and the materials used for memory, such as cores, thin films, etc. 15 1G T H E B E L L SYSTEM TECHNICAL J O U R N A L , JANUARY 19G4