The ferreed

This paper describes a class of new electromechanical switching devices, the ferreeds, which were developed for use as crosspoints in telephone switching networks. The ferreeds are characterized by-high-speed operation, sealed noble metal contacts, small size, and ability to respond to co-ordinate excitation. The choice of materials, magnetic circuits, winding configurations, as well as the experimental techniques, are discussed; existing types of ferreed devices are shown together with the pertinent performance data.