Recent developments in Bell System relays including sealed contact and miniature relays

Among the most important components in the general area of electromechanical devices are relays, which after many years in use continue, in modern form, to be essential elements in Bell System and military applications, including electronic switching systems. The most important recent developments are miniaturization, sealed contact relays using glass-enclosed contacts, and “remanent”-type devices. Ferreed and bipolar ferreed co-ordinate arrays and individual units are new and important switching elements. They make use of miniature glass-enclosed contacts in combination with “square-loop” magnetic material, such as ferrite or certain iron alloys. They are magnetic “latching” units and are operated or released by short pulses.