BOOLEAN ALGEBRA AND CIRCUIT DESIGN 



293 



of each piilso and the necessary "code" leads that must be si'oinuled at 

 th(>se times. Reference to the block diagram of Fig. 1 shows that the 

 output of the translator is not activated until the slow release RA relay- 

 releases after the last pulse of a digit has been received. Therefore the A 

 relay can be eliminated from these combinations since at the end of 

 every pulse the .4 and B relays are either both operated or both released 

 and hence only one is needed to indicate the condition of both. Table ITT 

 lists the munerous combinations which must close a ground path through 

 to each of the five code leads and the ZO lead. At the conclusion of the 

 algel)raic manipulation, the A and B contacts may be redistributed 

 e\'cnly since they perform interchangeable functions in translation. 



The objective in the design of the translating circuit is to obtain the 

 most economical contact network subject to a spring distribution that 



Table III 

 Translation 



Inconsequential combinations that may be used for simplification 



