Patent GB-276720-A (GB)
Title: Improvements in or relating to automatic telephone plants operating with line seekers
IPC: H04Q3/00
Filed: 1926-05-26
Abstract: 276,720. Marks, E. C. R., (Lorenz Akt.- Ges., C.). May 26, 1926. Automatic exchange systems.-A single-motion selector of the kind which is steered to a wanted sub-group by a marking switch, is provided with a plurality of resting positions from any of which it may commence its selecting movement.. The marking switch is adapted to put a driving potential on all the sub-groups except the wanted one, and on release the selected wipers are only advanced as far as the first contact set of the subgroup succeeding the wanted one. The invention is described with reference to a 100-point connector LSII with two line wiper sets I, III, V and II, IV, VI respectively associated with banks allotted to lines numbered 11 to 60 and 61 to 00 and common tens and units marking wipers VII and VIII. When the switch is taken into use the line relay J is energized and on the connection of positive battery to the test wire c the upper winding of relay V is energized over wipers II and III of the tens switch ZW, wiper II of the units switch EW and the units switch DE : the magnet DE does not respond. Relay V locks over contact v<2> and over contact v<4> drives the tens switch into its second position from which it is advanced to its third position over its wiper I in which a slow-release relay U is energized over its lower winding and a short-circuit is removed from the lower winding of relay V to mark the connector busy. On the tens impulses being dialled, the relapses of relay J close a stepping circuit i<1>, v<1>, u<2>, for the magnet DZ of the tens switch, if this digit is 6 to 0 a relay QH being energized over contact strip 9-13 and wiper I to connect up the lower wiper set of the connector. The wiper V of the tens switch is a compound one comprising four interconnected fan-shaped arms and its bank is connected by marking wires to the contact bank of the marking wiper VIII of the connector in such a manner that when the tens switch comes to rest a driving potential is put on the first contact of every double sub-group except the wanted one. For example, if the tens digit is 1 or 6 the switch ZW stops in its fourth or ninth position in which the wiper V engages contacts 2 to 5 or 2<1> to 5<1>, thereby marking all the sub-groups except 11 to 20 and 61 to 70. At the end of the two digits the relay U relapses, transfers the impulsing circuit to the stepping magnet DE of the units switch, and closes driving circuits whereby the connector is advanced to the first contact set in the wanted sub-group: the driving circuit on first contact sets extends over DLS, s<3>, y<3>, LSII, VII, ZWJ and IV, u<3>, EWII, D and on intermediate contact sets over DLS, s<3>, y<3>, LSII, VII, EWIII, D. During units impulsing a slowrelease relay Z is energized and this driving circuit is transferred over winding III of relay Z and contact z<3>. At the end of the units digit, or when the connector has engaged the wanted subgroup, relay Z relapses and the connector is driven over a circuit DLS. s<3>, y<3>, z', EWIII. D to. the contact set in the wanted sub-group marked by the wiper IV of the units switch EW. When the marked contact set is engaged, relay Y locks energized, opens the driving circuit and closes a test circuit for relay Hover wiper V or VI of the connector. If the wanted line is free relay H energizes, cuts out its upper winding to mark the line busy, and connects up the wipers I, III, or II, IV. The relay Y also closes a restoring circuit for the units switch EW which in its eleventh position closes a circuit over the two upper windings of the ringing relay L, which projects an initial ringing impulse over the wanted line and is then energized intermittently over its upper and lower windings and a stepping switch. When the called party answers relay S de-energizes the ringing relay S and the talking connection is completed. When the calling party hangs up, the relapse of relay V closes a restoring circuit for the tens switch ZW, and on relapse of relav S when the called party replaces his receiver a circuit DLS, s<3>, y<3>, LSII, VIII. EWIII is closed for driving the connector to the first contact set in the next sub-group.