Patent GB-399148-A (GB)
Title: Improvements in and relating to the electrical control of apparatus in telegraph and like signalling systems
IPC: H04L12/12
Filed: 1932-02-19
Abstract: 399,148. Electric selectors. STEADMAN, E. and EXCHANGE TELEGRAPH. CO., Ltd., 64, Cannon Street, London. Feb. 19, 1932, No. 5045. [Class 40 (iv).] In a system having a number of stations on the same line the selective connection or disconnection of one or more stations or the control, such as the switching on and off ot apparatus, e.g. lamps at selected stations, is obtained by the transmission of a number of character signals or groups of impulses, which signals or impulse groups are separated from each other by intervals which do not exceed a predetermined maximum. Each separate station or apparatus has a controlling receiver which converts a character signal or group of impulses associated with the selection of that station or apparatus into a single impulse, and the selection or operative connection is effected if these single impulses follow one another at intervals less than a predetermined maximum. The action of the controlling receiver may be effected through the shaft of a type wheel rotated by escapement mechanism and operated by a telegraph transmitter of the type described in Specification 12215/84, [Class 40, Electric telegraphs' &c.]. On the operation at the transmitting station of a character key corresponding to a letter of the call signal of the desired station, the escapement wheel 16 of the controlling receiver at the different stations is brought to its appropriate position and a prolonged impulse energizes the printing magnet 24, which through its pivoted armature 22 closes contacts 13, 14 of the station(s) or apparatus having the letter as part of the calling or controlling signal. The member 17, which is adjustable on the shaft 15 of the type-wheel, is set to correspond with the position of the type-wheel for the letter or impulse group of the particularizing signal allocated to that station or apparatus. In the arrangement according to Fig. 2, which operates-in response to a signal employing two different letters, the closure of contacts 13, 14 energizes the coil 29 of a slow-release relay 26 closing its contacts 39, 40. If the contacts 13<1>, 141 are closed by the transmission of,the second character of the calling signal before relay 26 releases, a second coil 30 of the relay 26 holds the contacts 39, 40 closed and the coil 31 of slow-release relay 27 is energized, moving its armature 37 to the contact 38. If the contacts 13, 14, corresponding to the second transmission of the first letter of the call signal, are closed before the relay 27 releases, the coil 33 of relay 28 is energized closing contacts 41, 42, which effect the closing of a local circuit which may include a switch controlling the connection or disconnection of apparatus or a switching on of lamps of a specified colour. When the contacts 13, 14 open, relay 28 de-energizes immediately and after an interval relay 27 drops. In an alternative arrangement, Fig. 3, which operates on the threefold transmission of the series letter, the first closure of contacts 13, 14 energizes the coil of slow-release relay 46, and in addition the coil 51 of relay 43, closing contacts 55, 56. Whilst the contacts 13, 14 remain closed the potentials from the sources 87, 98 neutralize each other at the junction point 95, of the windings 51, 52, and the winding 52 is without current. When the contacts 13, 14 open, the windings 52, 51 are energized in series, and the armature 58 is moved to contact 59. If the contacts 13, 14 are again closed before the slow-release relay 46 drops, relay 43 is maintained energized over the contacts 47, 48, and the winding 53 of relay 44 is energized, closing contacts 60, 61 and supplying from battery 98 to the junction point 104 a potential which, until the contacts 13, 14 open, is neutralized by the battery 87. When the contacts 13, 14 open, current from the battery 98 flows through the windings 53, 54 in series closing the contacts 63, 64. If the contacts 13, 14 are again closed before relay 46 drops and, therefore, before relay 44 is deprived of current, a circuit is completed over contacts 58, 59, 63, 64 to the winding 65 of relay 45 which pulls up, opening at contacts 68, 114 the circuits to the relays 43, 46, and closing at contacts 66, 67 the circuit to the winding 65, which remains energized until the contacts 13, 14 open. The operation of the relay 45 closes the contacts 41<1>, 42<1> controlling the circuit of a local switch mechanism which connects the power supply to the apparatus to be controlled, or effects control, such as the switching-on or off, of apparatus at the station selected.