Patent GB-669522-A (GB)
Title: Key sender circuit
IPC: H04M3/60
Filed: 1949-01-12
Abstract: 669,522. Automatic exchange systems. AUTOMATIC ELECTRIC LABORATORIES, Inc. Jan. 12, 1949 [Jan. 13, 1948], No. 872/49. Class 40 (iv). In a semi-automatic telephone system in which a key set is connected to a register by automatic switches under the control of an operator and in which a sender operates to send digits corresponding to those registered in the register and to clear them from the register, the registration of a digit causes a sender to be connected to a plug-terminated cord circuit at the operator's position which connection, provided the plug is in a trunk jack, initiates operation of the sender, there being provided means controllable by the operator for disconnecting the key-set from the switch-board after all the digits have been registered and further means for stopping operation of the sender and for disconnecting it from the cord circuit when all the digits have been cleared from the register. Facilities are provided for signalling the operator if trouble is encountered. Busy flash is provided for all-trunks-busy and called party busy conditions. General description. As shown in Fig. 1 the system comprises four exchanges, viz. a central office 10, distant office 20, remote office 30, and C.A.X. 40, the first three of which include manual toll-boards 50, 410, and 201 respectively. Each operator position of toll-board 50 consists of a position circuit 500, a telephone circuit 200, a cord and sender control circuit 1000, and a group of cord circuits including cord circuit No. 1. The control circuit 1000 is provided with digit senders No. 1 and No. 2 individually associated with the digit registers No. 1 and No. 2 respectively. Detailed description: Preparing toll-board 50 for use. In this description the Figure in which a piece of apparatus is included is indicated by the numerals other than the last two of its reference number. To prepare the first operator position for use the operator inserts the transmitter and receiver plugs P207, P208 into jacks J209, J210, respectively, thereby operating battery supply relay R230 which grounds C247 to bring up the ready relay R1055 in control circuit 1000. Start relay R1190 follows and operates sequence relays R1180, R1185 corresponding to digit senders No. 1 and No. 2 respectively, whereupon R1190 relapses. With R1180 up the select No. 1 relay R1070 is conditioned for operation and the select No. 2 relay R1195 is disabled so that digit sender No. 1 will be used for the first call. The operator selects an idle cord circuit by operating its talk key K313 to bring up connect relay R320 which locks in series with talk relay R210. The last relay removes ground from C246 to prevent the connect relay of any other cord circuit being operated; connects the talking wires to repeating coil 235; and grounds C245. The talking circuit is also extended to the rear and front plugs P301, P302 in multiple. The ground on C245 brings up talk relay R1050 followed by select No. 1 relay R1070 and connect No. 1 relay R1080 so that the key set K1000 is connected to digit sender No. 1 and digit registers No. 1 and the start relay of the sender pulls up. Sequence relay R1180 is released, sender No. 1 lamp L1021 is lit, and the connect relay R1630 is operated to connect the key set mark conductors C1001-C1004 to the four mark relays 1W, ... 1Z of the first register. Connect relay R320 also brings up the No. 1 cord relay R1140 in series with R210. C.L.R. calls in central office 10. The subscriber at station T401 on receiving dial tone from selector 406 dials " 0 " and is extended over an idle trunk 420. Line relay R450 operates and brings up hold relay R460, whereupon seize relay R470 (operated on seizure of the trunk) relapses. On the insertion of rear plug P301 into jack J440 the answer relay R465 and jack relay R480 pull up and the momentary operation of drain relay R475 connects impedance 471 to the trunk to prevent clicks due to electrostatic charge thereon. The operator answers the call and completes the connection. Calls to subscribers of C.A.X. 40. The operator inserts the front plug P302 into the jack J610 of an idle toll line circuit 600 and jack relay R690 busies the trunk. Sleeve relay R650 pulls up in series with the front supervisory relay R535 in the position circuit which being marginal remains down. Switch relay R645 operates and applies ground through the upper winding of supervisory relay R665 over the simplex of trunk line 710 to operate the simplex relay R750, whereupon hold relay R760 and cut-off relay R770 pull up in turn. The trunk 715 is thus busied to the selectors 706 and supervisory relay R740 is connected across the trunk 720 leading to the trunk line circuit 725 in which the line relay operates. The finder 705 of an idle finder-selector link finds the trunk 720 and R740 operates to the reversed battery from the selector 706. The consequent operation of control relay R745 removes the upper winding of R750 from the simplex circuit to bring up R665 and the subsequent reduction in the resistance of the sleeve circuit allows the front supervisory relay R535 to operate, so that the front supervisory lamp L304 is lighted to indicate that keying may commence. Assuming the first digit keyed to be " 4 " leads C1012 and C1013 are grounded and mark relays 1X, 1Y pull up and mark the fourth mark conductor M4. Transfer relay R1620 which is short-circuited by ground on release conductor C1501 until the key is released then pulls up in series with the mark relays, connect relay R1630 is released and connect relay R1660 is operated. The digits keyed are thus registered sequentially. Registers are provided for nine digits but the earlier registers may be used again for the tenth and later digits. Transfer relay R1620 brings up hold relay R1370 in the sender, followed by the send front relay R1045 and the No. 1 cord No. 1 send relay R1150, whereupon R535 and R540 relapse and L304 is extinguished. Low resistance ground on C344 is extended to C1030 to hold R650 and operate the stop send relay R1225 and the marginal shunt relay R1215. Control relay R1320 which follows inserts the resistor 1217 into the last operating circuit. Hold relay R1370 also brings up cycle relay R1480 followed in turn by impulse relay R1460 and cycle relay R1470, whereupon R1480, R1460, and R1470 release in turn. These three relays continue to operate cyclically and during each cycle R1480 flashes the sender No. 1 lamp L1021 and R1460 opens the loop between the pulsing-out conductors C1027, C1038, the latter without effect at this time as the restored alternate relay R1440 is short-circuiting the loop. Relay R1460 also operates the counting relays R1530, R1535, R1540, R1545, and R1550 in turn and then reoperates them in turn, control relay R1555 being operated at the end of the 1st, 3rd, 6th, and 8th impulses and released at the end of the 2nd-, 4th, 7th, and 9th impulses. Transfer relays R1520 and R1525 come up at the beginning and end, respectively, of the fifth impulse and transfer the test conductor C1473 from marking leads M1-M5 to M6-M0. In the present case only three cycles are completed to produce the initial space since the grounded initial space conductor C1474 is connected to M3 and when R1540 comes up this ground is extended to C1473 to energize both windings of alternate relay R 1440 and the upper winding of alternate relay R1450. These relays are differential and only R1450 pulls up, holds R1470 to stop further cycling, removes ground from C1465 to release R1540, and brings up the initial space relay R1310 which transfers ground from C1474 to the inter-digital space conductor C1475. The lower winding of R1440 is thus de-energized and the relay operates, removes the shunt from the pulsing-out loop, and releases R1470. The consequent release of test relay R1250 brings down the automatic ring relay R1420 which extends ground on C1029 to C1030 to shunt down the sleeve relay R650, whereupon switch relay R645 restores, disconnects J610 from repeating coil 620, grounds the tip of J610 and connects its ring to the simplex of line 710. As the tip and ring of J610 are connected together through the cord circuit and digit registers this ground holds R750. Relays R1480, R1470, and R1460 recommence cycling and transmit the first digit as ground impulses over the simplex. The relapse of R750 to the first impulse brings up dial relay R755 and control relay R745 for the duration of the train and R750 repeats the impulses over the loop of trunk 720 to the selector 706. When the fourth counting relay R1545 comes up it connects the grounded marking wire M4 to C1473 to bring down R1450 which holds R1470 and operates release relay R1610 in digit registers No. 1. Transfer relay R1620, the operated mark relays 1X, 1Y,  and the counting relay R1545 restore, followed by R1440 which removes ground from C1508 to allow transfer relay R1410 in sender No. 1 to put up in series with R1610 and transfer the marking circuit from C1505 to C1504 and the release circuit from C1508 to C1507. R1440 also releases R1430 and R1250 and shunts the pulsing-out loop. Ground re-applied to C1465 initiates the operation of the cycle and impulse relays to count off the inter-digital pause. On the release of R1250 the stop send relay R1225 and shunt relay R1215 relapse, ground is removed from C1030, and sleeve relay R650 reoperates over its upper winding in series with R1215, the marginal R1225 remaining down. Switch relay R645 and supervisory relay R665 then operate as before and the lower winding of R650 is connected in parallel with its upper so that R1225 pulls up. At the end of the seventh cycle R1535 connects C1475 to C1473 to bring up R1450 and stop cycling. R1535 is restored and R1440 operates to remove the shunt preparatory to the sending of the second digit. This and succeeding digits are sent in similar manner. After the operator has keyed up the wanted number she operates the call completed ke