. The Bell System technical journal . een inhibiting pulsesis forward biased by the —65 volt signal through the crosspoint relaywinding. The pulse which initiates the mark operations at the concentra-tor then passes through the gate to return a line busy signal to the centraloffice over this control pairs which is interpreted as a crosspoint closurecheck signal. f. Crosspoint Release Circuit The hold magnet of the central office crossbar switch operates, remov-ing the +100-volt operate mark signal after the crosspoint check signalis received. A slow release relay per trunk is operated directly
. The Bell System technical journal . een inhibiting pulsesis forward biased by the —65 volt signal through the crosspoint relaywinding. The pulse which initiates the mark operations at the concentra-tor then passes through the gate to return a line busy signal to the centraloffice over this control pairs which is interpreted as a crosspoint closurecheck signal. f. Crosspoint Release Circuit The hold magnet of the central office crossbar switch operates, remov-ing the +100-volt operate mark signal after the crosspoint check signalis received. A slow release relay per trunk is operated directly by thehold magnet. When the central office connection in the No. 5 crossbarsystem releases, the hold magnet is released. As shown in Fig. 14, with thehold magnet released and the slow release relay still operated, a —130-volt signal is applied in a simplex circuit to the trunk to break down agas tube provided in the trunk circuit at the concentrator. This tube in CONCENTRATOR CENTRAL OFFICE TO ALL CROSSPOINTSSERVED BY SAME TRUNK. 130V I Fig. 14 — Crosspoint release circuit. 268 THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1956 breaking down shunts the local holding circuit of the crosspoint causingit to release. The — 130-volt disconnect signal is applied during therelease time of the slow release relay which is long enough to insure therelease of the crosspoint relay at the concentrator. The release circuit is individual to the trunk and independent of thesignal sent over the control pairs. g. Pulse Signalling Circuits To control the concentrator four distinct pulse signals are transmittedfrom the central office. Two of these at times must be transmittedsimultaneously, bvit these and the other two are transmitted mutuallyexclusively. In addition, service request and line busy signals are trans-mitted from the concentrator to the central office. The two way trans-mission of information is accomplished on each pair by sending signals ineach direction at different times and
Size: 1829px × 1366px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
