A Series of Miniature Wire Spring Relays

The Western Electric Company has recently started production of the BF miniature wire spring relay (Fig. 1) and its variations. It is the intent of this paper to describe in some detail the background and course of development for these families of relays. Two basic pressures have been responsible for a growing demand for miniature relays in the telephone plant. The first of these is the modern trend toward miniaturization. Because of the premium on space in the telephone plant, there has been increased effort to put more equipment into less volume. This has been directly responsible for a need for smaller components, and relays are one of the major building blocks of telephone systems. The second pressure for miniature relays has come from the large scale introduction of semiconductor devices. These devices are generally small and mounted on printed wiring boards. However, for many circuit functions and for interfaces with existing equipment, relays are needed. Equipment designers have found it both difficult and impractical to use large relays in conjunction with printed wiring boards and small components such as diodes and transistors. This has resulted in a demand for a miniature relay which can be mounted compatibly with the semiconductor devices on printed wiring boards. 117