Patent GB-200804-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/42
Filed: 1923-06-25
Abstract: 200,804. Automatic Telephone Manufacturing Co., Ltd., (Assignees of Madsen, F. T.). July 15, 1922, [Convention date]. Automatic exchange systems.-Certain subscribers' lines A and selector trunks D, E, Fig. 3, on which supervisory observation may be required, are wired through a distributive frame DF to terminals in the bank of a special observation connector OC, Fig. 2, which can be controlled by the dial CD of an observation clerk over a trunk 49 - - 52 to select any particular line or trunk of those so connected and thus associate it with the recording equipment, Figs. 1 and 4. Connections between subscribers A, A<1> are established in the usual manner over line switches C, C', group selectors D and connectors E, the association with the recording equipment producing no appreciable effect upon the normal operation of the switches. A high-resistance polarized relay 102, bridged across the talking- conductors at the connector OC, normally energizes in series with a line relay 205, 208, 221, and holds open the circuit of relay 9, Fig. 1, but when the receiver at sub-station A is off its hook, relay 102 is short-circuited over the loop and permits relay 9 to energize and bring into action the recording equipment. Impulses dialled by subscriber A to control switches D, E are also repeated to relay 9, whereby a record of the impulses is perforated on a moving tape 82 and the three digits dialled are also indicated by numbered lamps picked out by switches MS<1>, MS<2>, MS<3>. A lamp L is lit when the called subscriber replies, and a lamp L<1> when one of the subscribers hangs up, whilst a record of the total duration of the call is also made on tape 82. Provision is made for intervention bv the observation clerk if a wrong connection is made. In the case of an incoming call to the subscriber A, the clerk is able to listen in, to supervise the transmission of ringing-current and the conversational qualities of the line. A number of trunks 49 - - 52 and connectors OC may be associated with one observation clerk, each being connectible to the apparatus 0 by means of a key K<2>, for example, in a multi-exchange system, one trunk 49 - - 52 may lead to each exchange In a modified arrangement, Fig. 5, which should be substituted for Figs. 2 and 3, the connector OC<1> is provided with a third wiper M and corresponding bank contacts to which are wired the release trunk conductors of selector trunks D<1>, a relay 111<1> operating when a call is in process to complete the circuit of relay 9. The polarized relay 102' has a condenser 12 in series with it so that it only responds to impulses and to reversals of current. With this arrangement, the seizure of a faulty trunk in which one of the three conductors is open is brought to the notice of the clerk by means of a characteristic mark on the tape 82. First arrangement; operation of connector OC by clerk to associate recording equipment with subscriber's line A. The operation of key K<2> completes a bridge across conductors 49, 52 in series with which relays 106, 107 energize and operate release relay 103. The movement of key K<1> to the right connects dial CD in the circuit and impulses corresponding to the first digit arerepeated by relays 106, 107 to vertical magnet 156. At the end of the digit, the relapse of relay 109 prepares the circuit of series relay 110 and rotary magnet 157, to which the second series of impulses is repeated by relays 106, 107. Relay 110 energizes relay 111 which locks up, and, upon the relapse of relay 110, a circuit 50, 118, 116, 136, 51 is closed for relay 9, but, if the line A is idle, this circuit is immediately opened at one of the contacts 112, 114 of polarized relay 102 which energizes over wipers 144, 146 in series with line relay 205 which does not energize. The clerk then throws key K<1> to the left whereby her listening set is bridged across conductors 49, 52. a resistance 12 in parallel with the receiver preventing the clicks due to dialling or the ringing currents from being uncomfortably loud. The circuits of the connector OC are such that, after taking observations on any line or trunk wired to a particular level, the wipers 144, 146 may be further rotated on to the next or a subsequent line or trunk in the same level by merely dialling one or more further impulses at the dial CD. Supervision of outgoing call from substation A. When subscriber A removes his receiver. line relay 205 energizes and initiates the usual operation of the line switch C, whilst relay 102 is short-circuited over the substation loop and permits relay 9 to energize. Relay 9 operates release relay 8 which grounds lead 54 to light lamp L<2>, to operate relay 73 to close the circuit of the motor M which drives the tape 82, and to energize a magnet 78 which causes a toothed wheel 79 to punch a dotted line in the tape as long as the receiver at the substation A remains off its hook. Relay 5 is also operated to transfer conductors 49, 52 to the control of relay 4. Relay 102 energizes in response to each opening of the loop circuit during the dialling of the first digit, each energization of relay 102 producing a corresponding de-energization of relay 9 which repeats the impulses over circuit 53 to the magnet 80 to effect a corresponding perforation of the tape, and also over the circuit 31, 58, 68 to stepping magnet 71 of switch MS<1> which lights a particular lamp indicating the value of the digit dialled. At the end of the digit, during the slight interval between the release of relays 7, 6, both of which remained energized throughout the digit, an impulse is sent over the circuit 29, 27, 26, 56 to the stepping magnet 65 of switch MS which advances wiper 68 on to its second contact leading to the switch MS<2>. The second and third digits are recorded in a similar manner by switches MS<2>, MS<3> respectively and on tape 82. At the end of the third digit, wiper 68 is moved on to its fourth contact over which it completes a circuit 7, 31, 58, 68, 55 for relay 4 which locks up, disconnects relay 5 and, during the short interval before relay 5 falls back, connects ground at armature 23 to conductor 49, at the same time disconnecting conductor 52. Relay 107 thus falls back and closes circuit 125, 122 for relay 104 which energizes in parallel with resistance 116 and bridges relay 103 in shunt of relay 102. Relay 103 is able to energize in series with line relay 221 of connector E, even though loop A is closed, and locks up relay 104 in the circuit 118, 115 in series with relay 9. As soon as relay 5 releases its armatures, conductors 49, 52 are again connected together and relay 107 re-energizes. When the called subscriber replies, the usual reversal of current produced by the operation of back-bridge relay 220 causes a momentary de-energization of relay 103, which at armature 115 is repeated to relay 9 and thence over circuit 30, 28, 53 to magnet 80 to punch the tape. At the same time an impulse is repeated over the circuit 30, 28, 31, 19 to the upper winding of relay 3 which is constructed of a small number of turns of high resistance so as only to operate armature 20, thus connecting up its lower winding which, however, is at first shortcircuited over contacts 19, 31, 30. As soon as relay 9 re-energizes after the impulse, relay 3 energizes over both its windings in series, pre. paring the circuit of relay 2 and lighting lamp L. (Relay 104 is made slow-acting so as not to respond to the momentary impulse which affects relay 103). If, at the end of the conversation, the called subscriber A' hangs up first, the release of relay 220 again reverses the current in the line and relay 103 responds to transmit an impulse to relay 9 which causes magnet 80 to punch a further hole in the tape, whilst relay 2 operating in circuit 19, 31, 30, lights lamp L<1> and extinguishes lamp L. When the calling subscriber A hangs up, the opening of the loop circuit causes relay 102 to energize and break the circuit of relay 9 which falls back and energizes magnet 80 to make a further record. Relay 8 is made very slow to release, and before it has released and during the interval in which the armatures of relay 206 are moving from their front to their back contacts, relay 102 is energized to interrupt relay 9 momentarily whereby a break is caused in the record made by magnet 80. Shortly afterwards, the release of relay 8 de-energizes relays 2, 3, 4; extinguishes lamps L', L<2>; completes a circuit over conductor 57 for the release magnets of switches MS - - MS'; deenergizes recording magnets 78, 80; and opens the circuit of magnet 73 which, however, is made slow to release, so that the tape is moved forward sufficiently for the complete record to be easily visible. Keys P<1>, P<2> are provided in case it is desired to dispense with either the tape recorder or the lamp indicator. Wrong connection. The clerk by cutting out resistance 12 by means of push P, may listen in on the conversation and if she finds that a wrong ccnnection has been obtained, she operates her talking key K and enquires of the calling subscriber what number was required. If this number does not agree with the number recorded on the lamps or tape recorder, she asks the subscriber to hang up and dial again. If the wanted number agrees with that dialled, the clerk requests the subscriber to wait, restores key K<1> and communicates with an attendant who looks for the fault. The lower springs of key K connect battery to conductor 52 and disconnect conductor 49 so that relay 106 de-energizes and closes a short .circuit 124, 127 around relay 103 which de-energizes and unlocks relay 104, the relay 9 remaining operated over other contacts of key K. When the faulty switch has been located, the attendant removes ground from the third conductor to release the connection, marks the switch busy and informs the clerk, who again throws key K<1> to the left and asks the subscriber to hang up and