Patent GB-367936-A (GB)
Title: Improvements in or relating to telephone or like systems
IPC: H04Q3/42
Filed: 1930-12-03
Abstract: 367,936. Semi - automatic exchange systems. AUTOMATIC TELEPHONE MANUFACTURING CO., Ltd., Strowger Works, Liverpool, and MACDONALD, G. M., 19, Belsize Avenue, Hampstead, London. Dec. 3,1930, No. 36521. [Class 40 (iv).] Wanted numbers are transmitted in code from an A-operator's position to an automatic exchange by sending, for each digit, a number of impulses over the junction in a forward loop circuit, the polarity of the impulses being varied in accordance with the condition of sets of storage relays on which the number is registered. Impulsing is controlled by synchronously stepping switches at the ends of the junction. Wipers of the switch at the outgoing end are connected to the forward loop, and contacts of the switch are connected to battery or ground over contacts of the storage sets. The windings of similar storage sets are connected to contacts of the distant switch which is stepped by pulses of either polarity, but when a pulse of a certain polarity is sent due to the operation of a storage relay at the outgoing end, the corresponding relay at the distant end is operated by a polarized relay in the forward loop. At the automatic exchange, the exchange designation is decoded by a step-by-step switch which hunts for contacts marked by the storage sets, and a B-C switch, set simultaneously, translates into routing number. The first digit of the exchange designation has been taken up in junction selection by the A-operator. If the wanted exchange is automatic, the routing and numerical digits are sent out by the step-by-step switch, to which the digit markings are connected in succession by the switch previously used as the distant synchronous switch. If the wanted exchange is a manual one, the B-C switch initiates circuit changes whereby coded numerical digits (of the form originally sent from the A-position) are transmitted to a call-indicator under the control of a further switch at the automatic exchange operating in synchronism with a switch at the call indicator to control the setting of storage relays thereat. The register-translators are connected to junctions over primary and secondary finder switches, and special trunking arrangements are described in this connection. In the following description, the first numeral of a reference (except for conductors) indicates the Figure to which it belongs. Preparatory operations and connection of distant register-controller. The operator plugs into jack 712 in response to a call from the manual substation shown in Fig. 7, relay 716 operates over the calling loop and opens the short circuit around resistance 725 to dim supervisory lamp 724, and the operator plugs into jack 731 of the junction to the automatic exchange. Sleeve relay 769 lights lamp 763 dimly and connects ground to conductor 1 which operates 801 over the first bank contact of wiper 815 of the sending switch. Back stroke magnet 832 is energized by 801 which also grounds conductor 2 to operate 779 which locks up and loops the junction at 789 so that relays 111, 104 at the automatic exchange pull up. Relay 765 in the loop pulls up and lights lamp 763 but shunt field relay 759 remains inert. Slow-to-operate relay 805, operated by 801, releases the magnet and the sender takes one step to prepare the connection of impulsing conductors 8, 9 and the windings of relay 823 to battery and ground over wipers 812, 813. Relay 801 holds over wiper 815. At the automatic exchange, relay 104 disconnects ground from conductor 5 to mark the junction in the banks of primary finder 224 .. 228 and grounds the start lead 6 which extends over allotter 245, 246 to relay 211 in the finder. Non- calling and busy junctions have ground connected to conductors corresponding to 5 and bank of wiper 228 so that magnet 229 steps until 201, no longer short-circuited by ground over wiper 228, energizes to prepare in-pulsing and out-pulsing circuits for the register-controller. The allotter is stepped on to the e next idle finder. Switching relay 115 in the junction relay group operates by ground returned over conductor 5, holds 104 independent of 111, energizes two-step relay 128 which pulls up its light spring 129, extends the calling loop to the in-pulsing conductors 70, 71, and replaces the loop to the incoming selector, Fig. 1, previously completed over 107, by the out-pulsing circuit over conductors 72, 73 which are looped at the primary finder. When relay 201 operated, ground was extended over wiper 234 of a secondary finder allotter to relay 306 in the secondary finder 238 .. 242 associated with the registercontroller shown in Figs. 4 to 6. Relay 306 operates 335 and completes a circuit for the finder magnet 328 which is stepped by ground from 210 in the case of idle primary finders and ground from 314 on the multiple in the case of secondary finders connected to registercontrollers. Relays 301, 307, magnet 328 and resistance 323 from balanced arms of Wheatstone bridge and when wiper 242 fails to find ground, no current flows in diagonal conductor 1604 so that 307, 301 operate in series with 328, 323 respectively. Relay 301 completes a stepping circuit for the allotter 234, 235, lights lamp 368 and prepares circuits for the switches shown in Figs. 5 and 6. If all register-controllers are busy, removal of ground by relays such as 301 from conductor 86 stops the allotter on its last contacts. Relay 307 locks itself and 301, opens the circuit of slow-torelease relay 335, connects battery and ground from contacts of this relay to wipers 240, 241, and connects ground from 314 over 68 to operate 218 which releases 211 but holds itself and 201 to ground on wiper 242. The operation of 307 and relapse of 211 extend the above-mentioned selector loop over wipers 238, 239 to contact 629 of relay 627 by way of contacts of relay 603. The battery and ground connected, during the release period of 335, over wipers 240, 241 to the calling loop operates relay 759 which cuts resistance 762 into the circuit of lamp 763 to dim it, and connects battery to the lower winding of two-step relay 757 which pulls up its light armature 754. When 335 has released, relays 341 and 344 are connected across the loop which is now without current so that 765, 759 relapse, 757 operates fully, and lamp 763 is flickered rapidly by interrupter 854, Fig. 8, to inform the operator that the distant apparatus is ready for keying. Relay 757 also disconnects the junction from relays 765 769 and switches it through to the windings of relay 823. At the distant end of the circuit, 306 is released by 335 and during its release period back-stroke magnet 352 of the distant synchronous switch 401 .. 108 takes a step, and 350 operates over 403. If any junction discharge operates either 341, 344 this is without effect. Transmission of digits. The required exchange has a three digit designation ; the first digit being represented by the choice of a group of junctions and the remaining digits being written on the key strip, Fig. 10. The operation of a key energizes one or a combination of relays 1001 .. 1012. The ground on conductor 12 operates 901 which connects ground from 13 to one side of relays 902,903, the other sides of which are also grounded over 12, while ground connected to any of conductors 14 .. 17 operates corresponding relays in the storage group 920 .. 924. These relays lock to 13 and mark contacts in the sending switch 812 .. 815 as described later. When the key is released, ground is removed from 12, relays 901, 902, 903 and resistance 904 form a balanced bridge with no current in 18, and 902, 903 pull up in series with 901, 904. to transfer conductors 12 and 14 .. 17 to the second register, the remaining digits being stored in similar fashion. Ground from 906 over wiper 814 operates 852 which extends the forward loop, previously completed from relays 341, 344 back over the junction to relay 823, to wipers 814, 813 which have previously taken one step. The terminals in bank of 812 are normally adapted to be connected to battery over 851<1> and those of 813 to ground, but any operated relay in the storage groups reverses, or prepares the reversal of, the connections over the corresponding terminals. It will be assumed that relays 920, 924 of the first storage group have operated. The reversed battery connections on the second terminals of the sending switch operate relay 823 and both relays 341, 344 (polarized), in the forward loop. At the sending end, two step relay 842 pulls up its light spring 844, relay 829 operates and locks, and magnet 832 energizes, while at the distant end, magnet 352 energizes to ground on wiper 405 (second terminal) and opens the loop. Arrangements are provided for preventing differences in the operating times of magnets 832 and 352 from interfering with the synchronous stepping of the switches. If 832 is quicker, 852, 829, 832 remain held since the loop is not broken and 823 is therefore still operated. If 352 is quicker, 832 is held until its interrupter spring 833 opens the circuit of 852 which releases 829. At the distant end, 352, if quicker, opens the loop, releases 341, 344, and 352 falls back to step wipers 401 .. 408, but the loop is not re-made since 823 at the sender has released, and two-step relay 842 fully operated to remove battery over 851<1> from terminal 2 of 813 and place it on terminal 6. Magnet 352 therefore remains inert until magnet 832 has stepped the sender to terminals 4. If 352 is slower the loop persists until it operates. The effect of difference in release periods of the magnets will now be considered. If 832 is quicker, its wipers are stepped on, and 852 re-operates to prepare the loop which however is not completed until 352 releases. This completion at interrupter spring 351 may occur before wipers 401 .. 408 have moved entirely off terminals 2 so that if 341 and 344 both operated on the second pulse over the junction, ground from wiper 405 on contact 3