A. F. BUBNS, in an article on testing of the crossbar system of telephony (Bell Lab. Rec., 20, No. 9 ; May, 1942), points out that in dialling systems a talking connexion is established through a ...

This Design Idea describes a handy continuity tester with two modes of operation: It may sound if it detects continuity between its two probes, or it may sound when it detects no continuity. The ...