Logic of relay circuits

REQUIREMENTS for relay circuits are usually stated on a cause and effect basis; that is, when certain events occur in a particular way, certain effects will be produced. If a clear logical statement of relations between causes and the desired effects can be made, a circuit of relays controlled by contact networks can be constructed which is analogous to the logical statement and consequently produces the desired results. A machine incorporating such circuits “knows” what to do for a definite set of circumstances; it is able to analyze a combination of preconceived conditions and produce a result which agrees with the basic pattern of logic laid out by the designer.