BOOLEAN ALGEBRA AND CIR' UIT Di^SIGN 



283 



ill operating torminatos tho output from the translator and simultane- 

 ously releases the relays in the counter to prepare it for the next digit. 

 Speeifte requirements imposed by the originating register circuit neces- 

 sitate the counting of one to eleven pulses; the use of a driving source 

 consisting of a single break-make (or transfer) contact with ground on 

 the ai-mature spring; and outputs as follows: 



1. Count of 1 tiirough 10: ground on two of the 0, 1, 2, 4, 7 output 

 leads ill the combination corresponding to the count. 



2. Count of 10: ground on the ZO lead. 



3. Count of 1 1 : ground on the lead only (this is a trouble-detecting 

 feature"). 



In adchtion, the design of the steering and register-storage circuit 

 reciuires that no output leads be connected together until the second 

 pulse is received. Furthermore, each relay is limited to a combination of 

 simple make and break contacts not exceeding a total of twelve. This uti- 

 lizes the maximum number of springs obtainable on presently available 

 rela3\s and also avoids the larger armatiu'e gaps imposed by transfers 

 which would result in a reduction in the relay speed of operation. Speed 

 requirements also do not permit the use of shunt release in the circuit 

 operation. 



COUNTER 



RELAY COILS AND 



ASSOCIATED CONTACTS 



FOR PRODUCING 



REQUIRED OPERATING 



SEQUENCE 



TRANSLATOR 



CONTACTS ON 



COUNTER RELAYS 



FOR TRANSLATING 



RELAY SETTINGS TO 



DESIRED OUTPUT 



CODE FORM 



r' 

 r' 

 r 

 r 

 r' 



- VIA STEERING 



CIRCUIT TO 

 4 > REGISTER OR 

 STORAGE 

 CIRCUIT 



'b_ 



Fig. 1 — The schematic of a portion of a dial pulse register circuit for counting 

 decimal code pulses and translating them to "two out of five" signals. (In the 

 symbolism used in the illustrations a cross indicates a "make" contact and a 

 vertical bar indicates a "break" contact.) 



