Switching circuits
In my quest to find out how to use obsolete circuitry to do interesting things in the name of art, I recently acquired a copy of “The Design of Switching Circuits” by Keister, Ritchie and Washburn. This book was written by members of the technical staff of Bell Telephone Laboratories in 1951 and covers the use of relays and cold cathode tubes in constructing logic circuits, state machines, circuits for counting, hunting, selecting and various other systems that were used in those days in telephone exchanges and computer construction.
Their circuit for counting and registering sequences of numbers dialed on a rotaty phone dial is given below, together with a timing diagram:
These circuits are interesting but I have developed good circuits for counting, e.g. BCD or binary counting using only relays and these can be found here.
