Patent GB-165036-A (GB)
IPC: H04M5/06
Abstract: 165,036. Drouet, L., and Thomas, A. June 17, 1920, [Convention date]. Addition to 164,754. Manual exchange systems and apparatus.-Relates to systems as described in the parent Specification in which an order wire is connected to a calling " A " operator by a call-finder. In one modification each order wire has allotted to it a number of call-finders, each serving a group of " A " operators, and in a second modification " A " operators have access to several order wires leading to a " B " position, the selection of an idle order wire being made automatically. In the arrangement shown in Figs. 1 and 2, an order wire connected to the terminals 52, 53, is associated with two call-finders A, B, connected together over the armatures 54, 56, of the cut-off relay 26. On either of the call-finders appropriating the order wire, the energization of either cut-off relay 26 or 26<b> causes the response of the relay 22, which connects both starting wires 19<a>, 19b to the battery 48, so that if a further attempt is made to seize the order wire, the lamps 18, 16 will glow until it is free. If the call-finders A, B make connection with different calling operators simultaneously, the order wire will only be connected to the operator served by the switch A, since it is disconnected from the switch B by the relay 26. In the arrangement shown in Fig. 3, two order wires 77<a>, 78<a>, and 77<b>, 78b are connected to two call-finders A, B serving the same group of operators. On the energization of a relay 22a or 22b, following the response of a cut-off relay 26 or 26<b>, the common starting wire 19<a> is connected to the starting relay of the other callfinder. If both order wires are seized, both relays 22<a>, 22<b> will be energized, and the starting wire 19<a> connected to the battery 91, so that upon another operator attempting to appropriate an order wire, the lamps 16, 18, Fig. 1, will remain illuminated until an order wire becomes free. When an order wire is seized, the relay 13, Fig. 1, at the " A " operator's position is energized, and removes a short circuit about its high resistance winding 58, thereby marking the operator's set busy. Modified circuit arrangements at one of the " B " operator's positions are shown in Fig. 4. When one of the " B " operators leaves her switch-board, a relay 68 (in series with the microphone circuit) de-energizes, and closes two parallel circuits extending over the differential windings 72, 73 of relay 74, order wire 77<a>, 78<a> (or 77<b>, 78<b>), Fig. 3, and the windings of relay 82. Relay 74 remains inert. but relay 82 illuminates supervisory lamp 85, and completes a circuit for the relay 22<a>, which connects the starting wire 19<a> to the other call-finder. During hours of curtailed service when neither " B " operator is in constant attendance, and both relays 82, 82b are energized, a circuit is not completed for relay 22<b>, and the starting wire 19<a> remains connected to the call-finder B. " A " operators are provided with a key 90, Fig. 1, by means of which the upper winding of the relay 74, Fig. 4, is energized to cause the response of the relay 74, and illuminate a calling lamp at the " B " position. The arrangements in Figs. 2 and 3 may be combined to provide a system wherein several order wires common to a " B " position and accessible to all the " A " positions are each provided with a number of call-finders, each call-finder serving a group of " A " positions. In another arrangement, each group of " A " operators is allotted an order wire for their sole use, and when this line is engaged the call is made upon an order wire common to all the groups.