Patent GB-278763-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/00
Filed: 1927-10-11
Abstract: 278,763. Associated Telephone & Telegraph Co., (Assignees of Bellamy, J. I., and Richardson, R. G.). Oct. 11, 1926, [Convention date]. Automatic exchange systems.- In a system using register-controllers of the code-translating type, the register - controllers are arranged in a large group and have access to a common group of primary exchange registers which in turn have access to smaller groups of secondary exchange registers. Some of the latter record one and others two exchange digits, the kind used being determined by the value of one of the exchange digits. A common distributing frame is provided, the cross-wiring of which in addition to determining the number and value of the routing digits, controls the advance of the sending control switch through blank positions and initiates the switch-through of the connection and the release of the registercontroller in accordance with the number of routing and numerical digits to be sent. both of which are variable. The exchange registers are released immediately after the routing digits have been sent. When a register-controller is taken into use, an associated switch RS, Fig. 2 hunts for an idle primary exchange register A, Fig. 5, which is raised to a particular level by the first exchange digit and selects either a single-motion secondary register B adapted to record a second exchange digit, or a two-co-ordinate secondary register BC adapted to record two or more exchange digits. Some of the levels of the register A may lead jointly to one and two digit registers B<1>, BC<1>, the wipers of which are multipled and their contacts so arranged that live levels of the register BC<1> correspond to dead contact sets of the register B<1>, and vice versa. In calls to a zero operator a primary register A is raised to its tenth level from which connections are made direct to the frame IDF. The jumpering at the frame IDF determines the setting of a class register CR, Fig. 4 prior to the transmission of the routing digits, the register in association with the control switch OCS, Fig. 2 bringing about the switch-through and the release of the register-controller. The wires from the lefthand side of the frame IDF and the conductors from the banks of the sending switch SS, Fig. 3 and the registers CR, TH - - - U, Fig. 4 are connected to taps spaced two cells apart on the exchange battery. The test circuits of the switches CR, SS include polarized test relays 303, 307, Fig. 3 which operate when the respective switches engage a conductor which is connected to a tap negative with respect to the tap connected to the left-hand side of the test relav over the frame IDF or the wiper of a numerical register. After the sending of each digit, a three-position polarized relay 301, Fig. 3 is connected in a test circuit, and in accordance with its direction of actuation either permits the next sending operation to proceed or initiates a skipping operation of the sending control switch OCS. Call to subscriber designated by two exchange digits and two numerical digits using exchange registers A, B. An idle register-controller is taken into use over a hunting switch in the usual manner the earthing of the release wire 153, Fig. 3 energizing the stop relay 306 to prevent premature operation of the sending switch SS. and closing the circuit of relay 214, Fig. 2 which starts the switch RS hunting for an idle A-digit switch. When an idle A-digit switch A, Fig. 5 is engaged, the upper winding of a two-step relav 501 is energized over the earthed test wiper, and the first step armature 505 is attracted to open the release circuit. The subscriber now dials the first digit 6 and the impulses are repeated over circuit 154, 201, 206, 503 to the vertical magnet 510, which steps the switch A to its sixth level in which it hunts for an idle single-motion register in known manner : At the end of the digit, the input control switch ICS, Fig. 2 is advanced a step by the joint action of relays 201, 202. When an idle register B is engaged, the switching relay 501 is energized over its lower winding and pulls up through its second step, closing a circuit for relay 531<1> which only operates its first-step upper armature since its lower winding is shortcircuited at armature 229 of relay 203, Fig. 2. The second exchange digit 2 is sent over the fifth wiper of the switch A to the stepping magnet 530 of the register B which is advanced to its second contact set (62). When the relav 201 relapses after the digit, the starting relay 203 is energized over its lower winding and the second wiper (from the top) of the switch A, the contact engaged by which wiper is cross-connected at the frame IDF with the third battery tap. Relay 203 locks over its upper winding earths the second and third contacts of the switch ICS which advances to its fourth position, connects earth to the interrupter 332, Fig. 3, and removes the shunt from relay 531<1>, Fig. 5. which connects up the four lower contacts to the frame IDF. The two numerical digits are recorded on the thousands and lundreds registers TH, H, Fig. 4 in the fourth and fifth positions of the switch ICS. Meanwhile the class register CR, Fig. 4 is advanced by impulses from the interrupter 332 and a test, circuit is completed from the third battery tap over the frame IDF, the first wiper of the register B, the second wipers of switches A, RS, and polarized test relay 303, to the right-hand wiper of the class register CR. The relay 303 does not operate until the right-hand wiper of register CR engages a contact which is negative with respect to the third tap connected to its upper end, and this occurs in its third position which is connected to the fourth tap. Relay 303 energizes a relay 304 which locks up, transfers the interrupter lead from register CR to the sending switch SS, transfers the circuit of stop relay 306 to the control of polarized relay 301, and de-energizes relay 303. Relay 301 is connected over wiper 210 of the outgoing control switch OCS in its normal position, the third wiper of switch A and the second wiper of switch B, and a jumpering wire of the frame IDF, to the seventh battery tap, and as this is positive with respect to the eleventh tap to which its left-hand end is connected, it operates to separate contacts 309 and de-energize stop relay 306, which connects the interrupter 332 to the stepping magnet of the sending switch SS, and closes a test circuit over wiper 210 of the switch OCS, polarized relay 307 and wiper 331 of the sending switch SS. On the first step of the switch SS, the pick-up relay 305 removes a shunt from the sending contact 328 and energizes the stepping magnet 208 of the switch OCS. The switch SS operates until its wiper 331 engages a tap (the eighth) negative with respect to the seventh tap to which the left-hand end of relay 307 is connected over the switches OCS, RS, A, B and the frame IDF, at which time relay 307 pulls up and energizes stop relay 306. Stop relay 306 re-connects the test circuit to the relay 301, closes a restoring circuit for switch SS, and opens the driving circuit of the outgoing control switch OCS which advances a step to connect the test wire to the second routing digit conductor over the fourth wiper of the switch A. The stop relay 306 now de-energizes since its auxiliary locking circuit over springs 309 is opened by the response of relay 301 and starts another sending cycle. Second and third routing digits of a value corresponding to the jumpering at the frame IDF of the contacts engaged by the third and fourth wipers of the switch B are sent in a similar manner, the outgoing control switch OCS advancing a step after each digit. The contact engaged by the fifth wiper of the switch B is jumpered at the frame IDF to the skip wire (twelfth tap) so that after the transmission of the third routing digit relay 301 operates in the reverse direction and at springs 308 closes a skipping circuit to advance switch OCS to its fifth position in which the test wire is connected over wiper 210 to the thousands register. As the office registering apparatus is never required after the switch OCS passes its fourth position, a circuit is now closed over wiper 209 for relay 215 which locks up over its lower winding and de-energizes relay 214, which frees the switch RS, the resulting removal of earth from the holding wire causing the release of the A-digit switch and the register B in known manner. The two numerical digits are transmitted in the fifth and sixth position of the switch OCS which after the last digit advances to its seventh position in which since the contact engaged by wiper 210 is dead, no third numerical digit having been dialled, relay 301 remains inert and leaves the stop relay 306 locked up over springs 309 until the release of the register-controller. The combined impulse and switching wire 154 is also earthed over contacts 312, 318, Fig. 3, the left-hand wiper of the class register CR (in its third position), and wiper 211, thereby energizing the switching relay in the trunk circuit and causing the disconnection of the register-controller in the usual manner. In the meantime the sending switch SS restores, the pick-up relay 305 relapses, and relays 306. 302, 203, 215, 304 are de-energized. Relay 302 closes restoring circuits for the switches OCS, ICS, and the registers CR, TH, H. The sending mechanism is prevented from overtaking the recording mechanism, as relay 301 cannot operate to open springs 309 and de-energize stop relay 306 to start a sending cycle until the corresponding register has been moved out of its normal position. Call to subscriber designated by three exchange digits and four numerical digits using registers A, BC. The switch RS seizes an idle A-digit register A as before, and when the first exchange digit 4 is dialled the register A steps up to the fourth level and selects an idle register BC. This is a two-co-ordinate switch the vert