Patent GB-748791-A (GB)
Title: Improvements in or relating to electrical gas discharge tube circuits
IPC: H04Q3/42
Filed: 1953-10-05
Abstract: 748,791. Automatic exchange systems. GENERAL ELECTRIC CO., Ltd., and BEESLEY, J. H. Sept. 24, 1954 [Oct. 5, 1953], No. 27239/53. Class 40 (4). [Also in Group XL (c)] In an arrangement for completing, on demand, a set of connections with a given order of priority each connection is associated with two gas-discharge tubes, the first of which when fired, completes the connection and the second of which if fired disables the first, and when a demand for a connection is received the second valves of all lower priority connections are fired and after a time delay the first valve of the desired connection is fired provided no higher priority demand has been received meanwhile. Arrangements are made to reset the circuit if two first valves are struck simultaneously. The arrangement is described with reference to three circuits 1 . . . 3 (e.g. registers), Fig. 1, capable of connection to a circuit 4 (e.g. a translator), over rectifier gates 8 enabled over leads 5 . . . 7 respectively. A demand for such a connection is signalled by positive potential applied to leads 11 ... 13, Fig. 2, the demands on 13 and 11 having highest and lowest priorities respectively. If a demand is received over lead 12 (say) the potential on this lead strikes the second valve 22 to disable the first valve 23 associated with the lower priority circuit. The potential on lead 12 also passes over lead 75 to a common delay circuit, Fig. 6, whose output passes over lead 21 to the coincidence circuit 47, 48 to fire the first valve 32, which applies enabling potential to lead 6 for completing the connection. The potential on lead 6 also passes to lead 80 to fire valve 34 which causes the firing of the remaining second valves 50, 51, the latter disabling valve 33 associated with the higher priority circuit. If during the delay time a demand for the higher priority circuit arrives valve 33 strikes to complete the connection and potential over leads 7 and 80 strikes 34 which in turn strikes 50 to prevent completion of the lower priority connection. If, however, two connections should happen to be completed simultaneously coincidence of potentials on leads 6, 7 (say) is detected in the circuit 52, 53, 54, Fig. 7, to strike valve 55. The output therefrom operates a trigger circuit, Fig. 8 (not shown) (see Group XL (c)), which cuts off a beam tetrode in series with the anode supplies of all the gas tubes to restore the circuit, whereupon it reoperates to establish the higher priority connection. In a modification suitable for a larger number of connections, Figs. 4 and 5, nine circuits are divided into groups of three, the groups being given priorities, and each line having its priority within the group. Thus circuits having demand leads 82 . . . 84 have higher priority than circuits having demand leads 11 . . 13. Circuits 67, 68, 69 are each identical with that of Figs. 2, 3; circuits 88 ... 90, 96 are identical with Fig. 7, and circuit 81 is identical with Fig. 6. On a demand being made on lead 12 valve 73 fires to apply potential to lead 80 of the lower priority circuit 67 so that it is unable to respond to any demands. The output from valve 73 is applied to the delay circuit 81 whose output enters circuit 68 over lead 21 and lead 6 is marked as previously described. This fires valve 85 and 86 follows to apply disabling potential to all groups over leads 80. In the event of simultaneous connection to two lines in different groups circuit 96 detects coincidence in outputs from two of the valves such as 85, 92 and fires 98 which causes removal of the anode potentials of all valves as previously described. Simultaneity of connection within a group is detected in one of the circuits 88 . . . 90 and causes 98 to fire with similar results. Specification 748,810, [Group XL (c)], is referred to.