Patent GB-677706-A (GB)
Title: Improvements in or relating to circuit-arrangements for use in automatic signalling systems for the numerical adjustment of a final selector under the control of pulses
IPC: H04Q3/00
Filed: 1951-02-01
Abstract: 677,706. Automatic exchange systems. PHILIPS ELECTRICAL INDUSTRIES, Ltd. Feb. 1, 1951 [Feb. 4, 1950], No. 2548/51. Class 40 (iv). In a single-motion final selector which is set by means of a local circuit of the " electrical escapement " type, defined in Specification 687,747, under the control of a tens impulse series and a units impulse series, each odd-numbered tens impulse places a " stop " marking on the first contact of each odd-numbered decade of the " escapement " bank and a " start " marking on the remaining contacts, whereas each even-numbered tens impulse places a " stop " marking on the last contact of each odd - numbered decade and a " start " marking on the remaining contacts. As shown, the " start " marking is earth and the " stop " marking is absence of earth, the markings being tested directly by the rotary magnet D of the switch by means of a test wiper T. When the final selector is engaged by a preceding group selector, busy relay C is energized and relay A receives the dialling impulses of the tens and units series. At the first tens impulse, A is energized and brings up relays Q and B, the latter being slow-releasing so that it holds during the impulse series. Rotary magnet D is energized and moves the switch away from its rest contact N, closing off-normal contacts kl, k2. Test wiper T fails to find earth at contact 11 and the switch stops there. At the end of the first tens impulse, A releases and relay P operates in series with Q. The second tens impulse re-operates A, and Q is now shortcircuited and released to connect earth to contact 11 so that magnet D once more drives the switch. It passes contacts 12-19, which are earthed throughout the tens impulse series, and stops at the last contact 10 of the first decade. At the end of the second tens impulse, A and P release. This interaction of relays A, P, and Q continues throughout the tens impulse series, Q being energized after an odd number of impulses and de-energized after an even number, thereby producing the markings set out in the opening sentence above. At the end of the tens impulse series, relay B releases and brings up relay E so that during the subsequent units impulse series the markings on all the contacts are controlled by relay Q. Relays P and Q, if energized, are released by the release of B. If the tens digit is even, say 2, the switch stops on the last contact preceding the required decade, contact 10 in this case. Relays A, B, P, and Q follow the units impulse series as they followed the tens series, Q interchanging the markings on the odd and even contacts so that the switch is stepped to the required contact. If, however, the tens digit is odd, the switch stops on the first contact, say 31, of the required decade. The first units impulse energizes Q to place a " stop " marking on the odd-numbered contacts, including 31, and the switch is not stepped, but thereafter the units digit drives the switch to the required contact. Relays A, B, P, and Q release at the end of the units digit, but E remains energized until released by the relapse of C at the end of the call which also completes a circuit for magnet D to drive the switch to its normal position where contacts k2 open and break the circuit. In a modification, the " stop " or " start " markings are provided by a battery and are tested by a separate test relay controlling the rotary magnet instead of directly by the magnet. The circuit comprising relays P and Q may be included in a cord circuit connecting a line-finder and a first group selector or in a common register instead of in the selector and may be used for controlling the group selectors as well as the final selector.