BE345808A - - Google Patents

Description

       

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  Automatic telephone system
The present invention relates to improvements relating to automatic telephone systems and more particularly to small office systems as used in private premises or in villages or similar circumstances.



   One of the objects of the present invention is to provide a small communication system having a capacity of up to five or ten speech circuits and using only line switches and relays.



   According to a characteristic of the present invention, the line switches of the calling line and of the called line are placed in position and actuated to establish communication with the same group of relays, the switch of the called line being actuated by the line switch. '' intermediate conductors which are all common to other line switches,
Line switches according to this feature of the invention may be of the tative type in which the wipers are jerk actuated at a single level by a ratchet and roohet wheel mechanism, or well of the plunger type and it must be considered new to employ line switches in this manner.



   Another feature of the invention relates to a metering and storing relay arrangement, in which the

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 tens digit is first counted on a series of counter relays, the number is smaller than the maximum number of pulses in a series to be counted, and is then transferred to the storage relays which are also more numerous. small reads the maximum number of pulses in a series to be counted, the counter relays then being used to count the ones digit; the storage relays and the counter relays then jointly control an operation such as actuation of a called subscriber line switch.



   Another feature of the invention relates to the establishment of calls from a small office to a main office through which the trunk line is read back to the trunk line relay group by different conductors but d. A similar manner to that in which a called subscriber line is connected to the trunk line relay group in the case of a local call.



   These and still other features of the invention will be better understood with the aid of Figures 1-15 of the drawings which show by means of the usual circuit diagrams sufficient features of the apparatus employed in the invention. the present invention to allow the description to be followed. It goes without saying, however, that various modifications can be made to the details of the circuits by those skilled in the art, without departing from the essence of the present invention.



   In the accompanying drawings, Figure 1 shows a subscriber's line switch No. 22 with the rows of ten sets of contacts which are available for the operation of the plunger arm of his line switch. The lower part of the figure shows the main switch circuit which is used to align the free plunger arms of the line switches of all subscribers. The plungers employed are of the self-aligning type, and provided with a spring-loaded control so that when a plunger is released by the de-energization of a plunger magnet at the end of a discharge, it is automatically brought into alignment. with the other free divers under the control of the main switch.

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   Figure 2 shows a group of battery powered relays, shown in connection with the subscriber line relay 22 of Figure 1; groups of similar relays are represented by rectangles designated by TRG 2-5 in fig. 1,
Figure 3 shows the subscriber line switches No. 52 and No. 56 so that the operation of the main switch in conjunction with the line switches can be more easily followed.



   Figure 4 shows one of two recorders in which the chain of counter relays shown in the upper left corner is used to first count the tens digit; this digit is then transferred to the storage relays W, X, Y, Z and the counter relays are then used to count the units digit.



   Figure 5 shows the marker, with the seven relays marking tens being shown on the left side and the relays marking units on the right side,
Figure 6 is a block diagram of another variation of the invention employing rotary line switches.



   Figure 7 shows calling subscriber and called subscriber line switches.



   Figure 8 shows a group of junction line relays.



   Figure 9 shows a recorder and a recorder finder.



   Figure 10 shows a main group of trunk line relays employed for incoming calls from the main office or outgoing to the main office.



   Figure 11 shows a battery power pack used to transform ordinary subscriber pulses into battery pulses.



   Figure 12 is a diagram of the connections to the main office.



   Figure 13 shows the circuit details of a switch

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 trunk used to make outgoing calls to the main office.



   Figures 14 and 15 show a layout of the subscriber line switches which differs from that shown in Figures 1 and 3. In this case, each subscriber has two line switches, one of which operates on outgoing calls and the other of which works during incoming calls.



   A different form has been described with the help of Figures 14 and 15 for desks having a larger capacity and allowing two conversation circuits. In this case, each subscriber is provided with two line switches; for example, subscriber N 22 is provided with an OLS output line switch
22 which is used for outgoing calls and an input line switch ILS 22 which is used for incoming calls. Likewise, subscriber No 56 is provided with line switches OLS 56 and ILS 56. Subscriber No 52 is moved by line switches OLS 52 and ILS 52.

   The line switches OLS 22, OLS 56, OLS 52 have access to the input ends of ten groups of trunking relays such as that shown in figure 2 tan say that the line relays ILS 22, ILS 56, ILS 52 have access to the output ends of the same trunk line relay groups. Two separate main switches OMS and IMS are planned; the main OMS switch controls the output switches such as OLS 22, OLS 56 and OLS 52, while the switch, main IMS controls the input line switches ILS 22, ILS 56 and ILS 52. The only change between This arrangement and that described in connection with Figures 1, 2, 3, 4.5 is that the line switches are modified and that Figures 14 and 15 should be substituted for Figures 1 and 3.

   The OMS main output switch is substantially of standardized construction and design while the IMS main input switch has been specially established to operate as will be described.

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   In order that the invention may be better understood, the description will be given of the establishment of a complete call and it will be assumed that subscriber No. 22 wishes to put himself in communication with subscriber No. 56. When subscriber No 22 lifts his receiver to start a call, he completes a circuit as follows: the beetle, LR line relay 22, contact 11, line 12 of the subscriber loop passing through the subscriber's device, with return via line 13, contact 14 to earth.

   Line relay LR 22 therefore operates by means of this circuit and closes contact 16 which completes a circuit for the downward attraction winding of the PM 22 plunger magnet, as follows: the battery, the top or pull down winding PDG of PM 22, contact 16, contact 15, contact 100, to earth.

   If it is assumed that the contact 100 is closed, as it is normally except when the main switch MS is hunting, the plunger magnet PM22 is therefore energized and brings the plon (geur into engagement with the row of fixed contacts in such a way that contacts 17, 18, 19 and 20 are closed and so that lines 12 and 13 are connected forward respectively to lines 21 and 22, while the earth is connected by contact 19 on contact with the row of fixed contacts of the main switch corresponding to magnet PM22 (this contact received the reference number 23).

   Closing a circuit via contacts 17 and 18 causes:. The completion of a circuit via the subscriber loop for line relay LR in the battery supply relay group figure 2, the line relay LR energizes and on contact 25 completes a circuit for the release relay RR.



   The RR release relay therefore activates and closes contact 24, which connects earth to the battery through release line 26, contact 20, the lower RCO winding of

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   the plunger magnet PM22. It should be noted that when magnet PM22 got excited, it. opened cor.tacts II and 14 which allows LR22 to de-energize. LR22 is, however, a slow release relay and therefore does not drop out for a minimal time, so contact 15 remains closed until the circuit for the lower coil of the plunger magnet has been completed.

   The current flowing through this winding is sufficient to keep contacts 17, 18, 19 and 20 closed and to keep contacts 11 and 14 open. Relay BR (RR), by energizing, closes contact 24 and then in addition to contact 27, which completes a circuit as follows: earth, contact 27, contact 28, conductor 29, contact 30 of the switching relay SRI, contact 32 of the switching relay SR2, the RTR recorder test relay, to the battery.



  RTR energizes and closes contacts 31 and 33 which completes a circuit passing through contact 31, retort follows: earth, contact 34, contact 31, the upper winding of relay SR2 to the retaining conductor 35; and a circuit is completed by contact 33 as follows: earth on contact 36, contact 33, the top winding of the SRI relay, conductor 37, conductors 35 and 37 terminate at the relay logger groups.

   If relay recorder group 1 is busy, earth is read back directly to contact 158 through contacts in the trunk line relay group that has taken RRG! Service, similar to contacts 27 and 28 in TRG1 If the RRGI relay logger group is busy, the upper SRI winding is simply short-circuited when the earth is connected to its lower terminal by closing contact 33; this has no effect on the SRI relay which is immobilized in the energized position at contact 157;

   closing contaot 3I places earth on the lower terminal

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 the release line 26 and to the contact 48 it connects to the conductor 49 the acoustic occupancy signal which goes through the capacitor, 50, the conductor 22, the conductor 13 to the line of the calling subscriber and returns via conductors 12 and 21, via the upper winding of the LR relay towards the battery) when the subscriber listens and hears the busy signal, he knows that he cannot complete the communication.



   If, on the contrary, the group of RRO I relay recorders is free, a circuit is completed as follows during the transmission of the first pulse of the series: earth, contact 40, contact 41, contact 42, conductor 43 the contact 51, the conductor 52, the contact 53, the contact 54, the contact 55, the contact 56, the counter relay FRI to the battery. The relay FRI therefore energizes and closes contacts 57 and 58. A connection circuit for the first impulse also passes through the change relay SHI and this relay therefore energizes and closes contact 59. which energizes the ACHI relay.

   The ACHI relay energizes and closes contact 60, which prepares an interlock circuit as follows for the FRI relay: earth, contact 60, contact 61, relay FRIA, contact 57, relay FRI, towards the battery. This locking circuit has no effect, however, as long as the earth is not removed from the upper terminal of the FRI relay by the conductor 52, at the end of the pulse. Consequently, when the first pulse ends, the FRIA relay energizes in this interlock circuit with the FRI relay, which opens contact 56 and closes contact 62. The FRIA relay operates other contacts including the goal will appear later.



   Both the SHI and ACHI relays are slow to unhook and as a result they remain energized during the pulse train and therefore the next operation which occurs occurs on the transmission of the next pulse when the LR relay de-energizes a second time. The LR relay closes a circuit which at this moment can be followed as follows: earth, contact 40, contact 41, contact 42, conductor 43, contact 51, conductor 52, contact 53, contact 54, contact 55, contact 62, relay FR2 to the battery. Relay FR2 therefore energizes and closes contact 63 which prepares as follows

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 a locking circuit for itself: earth, contact
60, contact 64, relay FR2A, contact 63, relay FR2 to the battery.

   This locking circuit is however ineffective until the moment the earth provided by the conductor
52 is removed from the upper terminal of relay FR2 at the end of the pulse. When this occurs, relay FR2A energizes in the latch circuit of relay FR2 and opens contact 61 which allows relays FRIA and FRI to release. At the same time it opens contact 55 and closes contact 65. The next impulse can be followed by the circuit previously described including contact 54, but at this time it passes through contact 65 instead of contact 55 for gain relay FR3 and battery. Relay FR3 energizes, closes contact 66, which prepares a latch circuit for itself, as follows: earth, contact 60, contact 67, relay FR3A, contact
66, the FR3 relay to the battery.

   This circuit only becomes effective as previously when the earth supplied by conductor 52 is removed from the upper terminal of relay FR3 at the end of the pulse, after which relay FR3A energizes and opens contact 64. , which releases the relays FR2A and FR2. At the same time, the relay FR3A opens the contact 54 and; close contact
68. The fourth impulse can be followed by the circuit described previously., Containing the contact 53, but instead of not being through the contact 54, it now goes through the contact 68, the contact 69, the relay FR4 towards the drums. The relay FR4 energizes and prepares a locking circuit for itself as follows: the battery, the relay FR4, the contact 70, the relay FR4A, towards the earth on the contact 60.

   As soon as the fourth pulse ends, the earth supplied by the conductor 52 is removed from the upper terminal of the relay FR4 and consequently the latch circuit becomes effective and the relay FR4A energizes, opens the contact 69 and closes the contact. 71; it also opens contact 67, which opens the locking circuit of relays FR3A and FR3, relays which de-energize as a result; relay FR4A also closes contact 72. The fifth pulse then passes through contacts 54, 55 and 56 to relay FRI and to the battery, since relays FRIA, FR2A and FR3A have been brought back to normal.

   The FRI relay is therefore energized, prepares a circuit

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 locked for itself as previously by contact 57, relay FRIA, contact 61, contact 60 to the earth, but contact 61 is this time short-circuited by contact 72. This is irrelevant since currently only five pulses are transmitted, but the purpose of this measurement will appear later when more than five pulses are produced.



   Upon completion of the fifth pulse, the FRIA relay energizes in series with the FRI relay as before; as the fifth pulse ends the series, the CHI relay then de-energizes and it is followed closely by the ACHI relay, but in the meantime a circuit can be drawn as follows: earth, contact 73, contact 74, contact 75, contact 188, relay FR4 being activated, contact 77, relay FRIA also being energized, contact 78, conductor 79, contact 80, the lower winding of relay Y, the winding bottom of relay Z, towards the battery; the Y & Z circuit relays are thus caused to exert themselves.

   The Y & Z relays complete by energizing lockout circuits for themselves, as follows: earth, contact 38 of the HRI relay, contact 84, contact 83 and the, for relay Z through the contact 82 and the upper winding of relay Z towards the battery, and for relay Y by contact 85 and the upper winding of relay Y towards the battery.

   As mentioned above, the ACHI relay de-energizes a little after the SHI relay drops out and therefore contact 84 opens a little after the events which have just been described, which removes a short circuit. of the DR disconnect relay so that the locking circuit for the Y & Z relays, instead of going through contact 84, now goes as follows: earth, contact 38, DR relay, contacts 82 & 85 and the top windings of the Z & Y relays respectively, to the battery.

   The Y & Z relays are therefore immobilized in the energized position via their upper windings, the DR relay energizes and opens the contact 83, which prevents the DR relay from being switched off. - sexcité during the following series of pulses when contact 84 is closed again. The DR relay opens contact 81 to allow the SCR relay to go off hook and open contacts 87 to 92 inclusive; it further opens contact 75 and closes contact 86 to allow a pulse to be emitted at the end of the

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 following series, by a different circuit, for a purpose which will be described later.



   When ACHI got off the hook, he also opened contact
60, which opens the locking circuit of relays FR4, FR4A,
FRI, FRIA, so that these relays return to the normal position and everything is ready for the transmission of the next series of pulses. The following series of pulses make the apparatus work, with regard to fig. 2, as before and the pulses can be followed by earth by contact 40, contact 41, contact 42, conductor 43, contact 51, conductor 52, contact 53, contact 54, contact 55, contact 56, the FRI relay to the battery, while a connection circuit also extends through the CHI relay to the battery.



   The CHI relay is energized as before, opens contact 73 and closes contact 59. ACHI relay also energizes as before and closes contacts 60, 84 & 74 and opens contact.
144. At contact 60, it prepares a locking circuit for the FRIA relay as follows: earth, contact 60, contact 61, relay FRIA, contact 57, relay FRI to the battery. However, this circuit becomes effective at the end of the first pulse only, when earth is removed from the top terminal of the FRI relay.

   When this pulse ends, the FRIA relay energizes in series with the FRI relay, opens contact 56 and closes contact 62, which prepares an excitation circuit for the relay.
FR2 which, as described previously, is energized at the start of the second pulse and is immobilized in the - energized position, in the following locking circuit: the battery, the relay FR2, the contact 63, the relay FR2A, contact 64, contact 60, to earth. At the end of the second impulse, the relay
FR2A gets excited; during the third pulse the relay FR3 is exited at the beginning and the relay FR3A at the end as described previously; and during the fourth pulse, the relay FR4 energizes at the beginning and the relay FR4A at the end.

   As will be remembered from the previous circuit, each of the successful relays opened the locking circuit of the previously energized relay, so that at the end of the fourth pulse, the relays FR4 and FR4A were alone energized, and these remain energized for the remainder of the series of pulses. FRI and FRIA relays

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 being energized at the end of the fifth pulse, as described previously and the relays FR4 and FR4A remaining energized, the sixth pulse can be directed as follows: earth, contact 40, contact 41, contact 42, conductor 43, contact 51, conductor 52, contact 53, contact 54, contact 55, contact 62, relay FR2 to the battery.

   Relay FR2 energizes and prepares a latch circuit for itself by means of contact v63 in series with relay FR2A, contact 64, contact 60, to earth. At the end of the sixth pulse, the FR2A relay energizes in series with the FR2 relay in this locking circuit and opens the contact 61. The FRI and FRIA relays are however not de-energized since they are locked at the energized state by means of contact 72 independently of contact 61. Consequently, at the end of the sixth pulse, the relays FR2 and FR2A remain energized and the following six relays are all energized at this moment: FR4, FR4A, FR2, FR2A, FRI, FRIA, and all these relays depend on the earth at contact 60.

   At the end of the series of pulses, the CHI relay de-energizes and is followed, after an interval, by the de-operation of the ACHI relay, but in the interval thus produced an extended series of operations are carried out and will go on. be described now.



   When the CHI relay is de-energized, a circuit is matched as follows: earth, contact 73, contact 74, contact 86, SDR relay to the battery. The SDR relay energizes in sequence, opens contact 53 to prevent new pulses from affecting the meter relay chain, and closes a latch circuit for itself at contact 93, as follows: the battery, the SDR relay, the contact 93, the contact 39 to earth and the SDR relay therefore only becomes dependent on the HRI retaining relay. At contact 111, the SDR relay closes a circuit going from the battery through the ACHI relay, contact 111, contact 110 to earth, to keep the ACHI relay energized until the main switch has completed its flushing operation. as we will see later.

   The ODR relay also closes the oon tact 94, which connects the earth through the conductor 95 to energize the start relay SRM of the main switch. This relay therefore operates and closes contact 99, which completes a circuit for the OMR open main relay which exoj

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 te and disconnects the earth at contact 100 of the open main conductor OM. which prevents the operation of the plunger magnet of any subscriber if the latter picks up his replayer while the main switch is driving out on contact
96, the SRM relay completes a circuit for the lower winding of the latching differential magnet, as follows; earth, contact 96, the bottom winding of the LM locking magnet, to the battery.

   The LM locking magnet therefore activates and closes contact 97. At contact 97 it connects the earth to the OMR relay, but this has no effect since the earth is supplied to contact 99 by the remaining SRM relay. energized until the main switch has finished its flushing operation; the contact
97 is intended for the case where the main switch is looking for the input end of a free group of trunk line relays, in which case the SRM relay is not energized.

   Auxiliary fired air for the upper winding of the locking magnet, which winding is wound in the opposite direction to the winding which has just been energized in circuit with contact 96, is now connected in a circuit extending as follows: earth, contact 96, the upper winding of the LM rusting latch magnet, contact ICI, contact 102, wiper 103 from the main switch to the contact with which the wiper is in take. This circuit therefore depends on the potential prevailing at the contact on which the wiper 103 is based at this time. The locking magnet releases, as is well known, the main switch by energizing, so that the latter moves all the free plungers around the perimeter, at the same time moving the rubbers. 103 & 606.

   Consequently, as soon as the slider 103 rests on a contact connected to the battery, the windings of the locking magnet LM are energized in opposition to each other and the locking magnet de-energizes; the main switch is then immobilized and contact 97 is open. It will be seen below that the main switch flushing operation took place between the drop of the CHI relay and the drop of the ACHI relay and that during this interval the SDR, SIR and FR relays were successively energized.



  When the ACHI relay then drops, a circuit is completed for the SR relay of the TRGI trunk line relay group, which relay in turn completes a circuit for the COR relay which switches off.

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 circuit the relay logger group. The SDR relay de-energizes and removes the earth from the conductor 95, the SRM relay drops out and opens the circuit of the OMR relay which drops out after a short interval and closes the contact 100. We will also see later that the operation of the control arm. PA56 plunger occurs at the same time as the operation of the FR relay in the RRGI relay register group.

   It is obviously necessary for the main switch to position all the free divers near the output or answer end of the group of line relays through which the call for subscriber 56 was initiated, and the battery has accordingly been connected to contact 105 by lead 104 as a result of operation of the SDR relay upon completion of the second digit; the contact 105 corresponds in position to the connection of the output end of the group of line relays in the row of fixed contacts of the line switches.

   The connection of the battery to the conductor 104 can be traced as follows: the battery, the SIR selection start relay, the contact 108 the conductor 107, the contact 106, the conductor 104 the contact 105, the wiper 103, the contact 102, the IOI contact, the upper winding of the LM differential lock magnet, contact 96 to earth;

   and as a single circuit such as the one just described can be closed at a time and therefore only one relay such as SIR can be energized at a time, assuming that the SIR relay (which, as as described,. is associated with the recorder which in turn is associated with the group of junction line relays TRG1) is actuated, it can be seen that all the plungers have been brought into alignment against the action of the connected springs at the output end of the TRG1 re relay group shown in fig. 2. The SIR relay energizes by means of this circuit and closes the contact 109 for a purpose which will be described later, and it opens the contact 110, which opens the restraint circuit for the ACHI relay, which has been extended by contact 111.

   At contact 124, the SIR relay closes a circuit for the units relay as will be described below and at contact 112 it closes a circuit for one of the tens relays. When the SIR relay closes contact 112, a circuit is completed as follows: earth, contact 112, contact 113 of relay Z, which, as we remember, was energized after the transmission {of the first digit , the

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 contact 114 of relay Y, which was also energized, the driver
115, the TD5 relay, to the battery. The TD5 relay is provided individually for subscribers whose first digit is five and therefore it is actuated each time a subscriber with one of these numbers is called.

   As in this example, subscriber 56 is called, relay TD5 energizes and closes contacts
116 to 122 inclusive. Earth is connected through these contacts to each of the seven conductors such as conductor 123 which receives its connection to earth at contact 121 and then goes directly to subscriber line switch 56. Similar single conductors connect each of the other contacts 116-122 inclusive to one of the subscriber line switches whose numbers have five as the first digit.



   Connecting the earth to conductor 123 causes a circuit to be completed for the UCR56 relay as follows: earth, contact 121, conductor 123, contact 600, winding of UCR56 relay, to the battery} the UCR56 relay energizes, which opens contact 602 and closes contact 603.



   It is seen that the earth connected to conductors such as conductor 123 closes a circuit for each of the relays such as UCR56, i.e. relays UCR5I-55 and UCR57, provided that the corresponding line switch does not be not busy. If one of the subscriber line switches 51-57 is busy, the relay corresponding to relay UCR56 will be switched off at a contact corresponding to contact 600.



   In the other example shown, namely that of the subscriber's line switch 52, if the line switch is free, a circuit is closed for the UCR52 relay by the following means: earth, contact II7, the conductor 98, the 60I contact, the UCR52 relay, to the battery; the UCR52 relay thus energizes and opens the 604 contact and closes the 605 contact. If the line switch had been busy, the UCR52 relay circuit would have been opened at the 601 contact which is kept open during a call by the coil. lower part of the PM52 relay.



   The SIR relay additionally closes contact 124, which completes a circuit as follows: earth, contact 124, conductor 125, UR units relay, to battery UR relay energizes and

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 closes contacts 126 to 132 inclusive. Of these, the switch 127 is connected to the conductor 133 which is connected to contacts such as 603 of the UCR relays of the line switches of each of the subscribers whose numbers have six as a second digit. Each of the other six contacts such as 127 is connected to a corresponding series of seven contacts.

   In the additional example shown, the contact 131 is connected to the conductor 630 which leads to a similar contact of the UCR relays of each of the subscribers whose numbers have two as the second digit, for example the contact 9 of the UCR22 relay and the contact 605 of the UCR52 relay.



   In the present example, the UCR56 relay operates and at contact 605 it completes a circuit for the attraction winding of subscriber No 56 and that subscriber only, as follows: the battery, l top winding of the FR relay, contact 109, contact 188, contact 77, contact 134, contact 135, conductor 136, contact 127, conductor 133, contact 603, attraction winding the PM56 magnet of the subscriber line switch No 56, to earth. The attracting winding of the PM magnet 56 energizes accordingly and forces the plunger of the subscriber line switch to dip by closing contacts 137, 138 and 139, which establishes a connection with the TRG1 trunk line relay group.



   If subscriber No 52 is free, relay UCR52 operates and closes contact 605 but no circuit is completed for magnet PM52, since conductor 630 is only connected to the upper winding of relay FR when the number 2 of the units has been registered by the counter relay chain FR1 to FR4. Operation of the PM56 relay also opens contacts 140 and I4I, which switches off line relay LR 56. The UCR56 relay circuit is open at contact 600, but the relay remains actuated for a sufficient time to allow to PM56 to stop in the energized position by means of its lower winding before the circuit of its upper winding is cut at contact 603.



  The lower winding of the PM56 magnet is energized by means of its lower winding, contact 138, release line conductor 143, to earth on contact 24. Note that earth is already waiting on the release line conductor 143, so that a wax is completed for the in-

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 lower bearing of relay PM56 as soon as contact 138 is closed. If the called line was busy, no circuit would be completed for the FR relay in series with the PM56 relay pull winding and therefore the FR relay would not energize.



   It is understood that all the preceding operations took place during the interval between the energization of relay CH1 and the de-operation of relay ACHI. Remember that the ACHI relay circuit was opened when a circuit was closed for the TD5 relay at contact 102.

   The ACHI relay, however, due to its slow stall characteristic, was held actuated for a short period of time until the FRI relay energized after the free line switch plungers were brought into alignment. face of the output end of the group of junction line relays in question (group of junction line relays shown in fig. 2). If the FR relay has not energized before the ACHI relay releases, the following circuit is completed: earth, contact 73, contact 144, contact 145, contact 146, conductor 147, contact 148, conductor 46, the upper winding of relay BR, towards the battery.

   The BR relay energizes accordingly and gives the busy signal in the manner previously described. On the other hand, if the subscriber N) 56 had been free, the attracting winding of the magnet PM56 would have been energized and the relay FR would have energized; the FR relay would have opened contact 146 and closed a locking circuit for itself through contact 149 and contact 39 to earth, so that when the ACHI relay was de-energized, the FR relay would be immobilized and no circuit would only be completed for the occupancy relay. By opening contact 60, ACHI releases the relays FR4, FR4A, FR2, FR2A, FRI, FRIA so that all the counter relays are brought back to normal.

   The ACHI relay completes a circuit as follows, when it de-energizes while the FR relay is energized: earth, contact 73, contact 144, contact 145, contact 640, conductor 150, contact 151 , the SR switching relay to the battery. SR activates accordingly and is locked in the energized position by means of the following circuit: battery, switching relay SR contact 152, contact 153, to earth on contact 24. It closes contact 154 , which completes Apple follows a circuit for

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   the COR interrupt relay: the battery, the COR relay, contact 154, to earth on contact 24.

   Note that the interrupt relay is also energized each time the BR relay energizes due to the closing of contact 155 and the circuit is completed as follows: earth, contact 24, contact 155, the COR relay, towards the battery. Whether the calling subscriber is busy or whether the called subscriber is connected and the relay SR energized, the relay COR is therefore energized and locked in the energized state by means of contact 156, independently of its initial contact. excitation, at the same time opening the contact 42 so as to prevent new pulses, accidentally formed au'ca- DRAN, from being transmitted to the counter relays.

   It also opens contact 28, which interrupts the restraint circuit for conductor 29 by releasing the SRI relay which was locked in the energized state at contact 157, and at the same time it removes the earth from the circuit. retained by contact 158 and conductor 37, which releases the HRI restraint relay. This relay consequently de-energizes, opens contact 38 to allow the DR relay and the Y and Z storage relays to de-energize and return to normal; at the same time, it opens contact 39 which allows the SDR, SIR, FR relays to de-energize. As a result, the relay register group RRG1 is returned to the normal state and can be used to establish the connection of another call.

   On energizing, the SR relay closed contacts 159 and 160 which connected the ringing current as follows: the battery, the ringing current source, the contact 159, the conductor 160 the contact 137 , the conductor I6I, to the equipment of the subscriber called with return by the conductor 162, the contact 139, the conductor 163, the contact 650, the ringing trigger relay RTR to earth. The subscriber's ringer therefore operates although the RTR relay does not energize in this circuit. When, on the contrary, the called subscriber picks up his receiver, a circuit is completed for the relay RTR which energizes and opens a contact 153, which allows the relay SR to be released.

   On releasing, SR opens contact 650, after which the RTR relay de-energizes but without any effect since the SR relay circuit is now open at contact 152, the SR relay legally closes the contacts.

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164 and 165 which connects the rear bridge relay BBR between the conductors of the loop of the called subscriber so as to supply the battery to the latter as follows: the battery the upper coil of the relay BBR, contact 164, the driver
160, contact 137, conductor 161, through the subscriber's equipment, conductor 162, contact 139, conductor 163, contact 165, lower winding of the BBR relay to earth.

   On energizing, the BBR relay closes contacts 165 and 167 which completes the conversation circuit to the calling subscriber, which circuit can be followed by means of the thick lines.



   Note that while the bell was on, the going subscriber obtained ringing current by means of capacitor 641, capacitor 642, conductor 21, contact 17, conductor 12, receiver receiver. the subscriber, conductor 13, contact 18, conductor 22, to earth on relay LR. In the event that the group of junction line relays of fiG.2 are retained in service for a time of exaggerated length, it is provided with a circuit which is completed as follows by the relay RR for the device T thermostat or other slow-acting device: earth, contact 168, contact 169, contact 170, thermostat, to the battery.

   The thermostat does not get excited unless its circuit is closed for three minutes, for example, but it must be understood that this time can be modified according to the wishes and it should be further noted that its circuit is open as soon as possible. that the SR relay is energized to establish communication or that BBR is energized to complete the conversation circuit. It can therefore be seen that if by chance the group of junction line relays remains associated with the relay recorder for a time exceeding a certain time allowed, the thermostatic device operates and connects the battery to the winding. lower winding of relay BR as follows: the battery, the thermostat winding, the I7I contact, the lower winding of the BR relay, ¯ the AR signal relay to earth.

   The relays AR & BR therefore energize in this circuit) AR gives a signal to an attendant so that he can investigate what is the cause of the delay, while the energization of the relay BR serves to give a signal. Acoustic reception to the calling subscriber in the manner previously described, and also to operate the interrupt and disconnect relay

  <Desc / Clms Page number 19>

 thus neotate the relay recorder group that is in service.



  It can therefore be seen that a call has been transmitted to subscriber No. 56 and that a communication has been established. To undo the communication, the calling subscriber hangs up his receiver and the line relay LR de-energizes as a result, which opens the circuit of the RR relay which de-energizes and, at contact 24, removes the earth of the release line conductor 26, after which the interrupt relay COR and the lower winding of the magnet PM56 de-energize. This has the effect that the plunger of the magnet PM56 falls back and loosens the connection to the called subscriber at contacts 137, 138 & 139, so that the BBR relay de-energizes, that the called subscriber has hung up. or not its receiver.

   The relays are therefore all returned to normal, with the calling subscriber's line switch also returning to normal when contact 24 is opened and earth is removed from release line 26.



   It is understood that the operation would have been similar if the relay SR2 had been energized instead of the relay SRI, the only difference between these two relays is that the relay SRI- receives preference over the relay SR2. The RRG2 relay group, which is not shown, is identical to the RRG1 relay group.



   With regard to the RRG1 recorder relay group, it should be noted that only a description of the effects of transmitting series of five and six pulses has been given. It can be seen that the counter relays FR1 to FR4, FRIA to FR4A are successively energized during the first four pulses, and consequently, if the first digit consists of a series of 1 to 4 pulses, circuits are completed as follows when relay CH1 de-energizes: (it is assumed that the first digit is one) earth, contact 73, contact 74, contact 75, contact 76, contacts 172, 173, 58, 87, upper winding from relay W to the battery.

   The W relay locks in the energized position in series with the DR relay by means of contact 174 when the ACHI relay de-energizes, and closes contact 175, so that when the SIR relay energizes subsequently , it completes a circuit through contact 112, contact 177, contact 178, contact 179, contact 175 to conductor 180 leading to relay TD1 which is / associated with the control lines.

  <Desc / Clms Page number 20>

 subscribers in whose number the first digit is a.



   We will now assume that the number two is the first digit transmitted. The relays FR2, FR2A become immobilized in the excited state and consequently, at the end of the series, when the relay CH1 de-energizes, a circuit is completed as follows: earth, contacts 73,74,75 , 76,172,181,88, the upper winding of relay X towards the battery. Relay X is therefore energized and locked in the energized state by means of contact 182 in series with the relay.
DR when relay ACH1 de-energizes, and closes contact 184 so that when SIR relay energizes, it completes a circuit as follows: earth, contact 112, contact 177, contact
178, contact 184, conductor 190, relay TD2 to the battery.



   We will now assume that the number 3 has been transmitted. In this case, the FR3 and FR3A relays are the only ones energized at the end of the series of pulses and a circuit is completed as follows when the CHI relay has de-energized: earth, contacts 73,74,75,76,185 89 , the upper winding of relay Y towards the battery. Relay Y energizes and locks in the energized state by means of contact 85 in series with relay DR when relay ACH1 de-energizes. It opens contact 178 and closes contact 186 so that when the SIR relay energizes, a circuit is completed as follows: earth, contacts 112,177,186, conductor 187, relay TD3 to the battery.



   If the first digit had been 4, relays FR4 and FR4A alone would have been energized at the end of the series of pulses and a circuit would have been completed at the end of the fourth pulse when relay CH1 de-energized, in the following manner: earth, contact 73, contact 74, contact 75, contact 188, contact 189, contact 90, the upper coil of relays Z, towards the battery. Relay Z is energized and rusted in the energized state by means of contact 82 in series with relay DR 'when relay ACH1 de-energizes, opens contact 177 and closes contact 113.

   Consequently, when the SIR relay energizes, a circuit is completed as follows: earth, contacts II2, 113,190,191,192, conductor 193, celais TD4, to the bat-

  <Desc / Clms Page number 21>

 
We have already given the desoription of the oas in which the number five is formed on the dial, in which case the relays FR4, FR4A, FRI and FRIA remain energized at the end of the series of pulses.



   When six pulses are transmitted, the relays FR4, FR4A, FR2 FR2A, FRI, FRIA are all immobilized in the excited state as has already been described. We will now assume that six is the first digit, in which case when relay CH1 drops out at the end of the series of six pulses, a circuit will be completed as follows: earth, contact 73, contact 74, contact 75, contact 188, contact 77, contact 134, contact 135, conductor 136, contact 91, the lower winding of relay X, relay Z to the battery. The X and Z relays energize in this circuit and lock in the energized state, by means of the contacts 182 and 82, respectively, in series with the DR relay, when the ACH1 relay de-energizes.

   As a result, when the SIR relay energizes, a circuit is completed as follows: earth, contact 112, contact 113, contact 190, contact 194, conductor 195, relay TD6, to bat. - terie.



   If the first series of pulses had been seven, then when the CHI relay drops out at the end of the first series of pulses, the relays FR4, FR4A, FR3, FR3A, FR2, FR2A, FRI, FRIA would all be energized. and therefore a circuit would be completed as follows: earth, contacts 73,74,75,188,77,134,196,92, the lower winding of relay W, the lower winding of relay Z to the battery. The Z and W relays are consequently energized in series and are locked in the energized state by means of the contacts 174 and 82, respectively, in series with the DR relay, when the ACH1 relay de-energizes.

   Consequently, when the SIR relay energizes, it completes a circuit as follows: earth, contact 112, contact 113, contact 190, contact 191, contact 176, conductor 197, relay TD7 to battery. It is not necessary to give a description of the effects for each of the unit digits from 1 to 7 since the operation is similar regardless of the value of the digit.



   It must be assumed that as in the proposed arrangement there are only five conversation circuits, the maximum number of subscribers will be less than fifty, because otherwise there would not be enough.

  <Desc / Clms Page number 22>

 Conversation circuits are available for simultaneous use, unless, of course, the traffic is very low. Therefore, none of the digits of the subscriber numbers will imply the transmission of more than seven pulses in a series. As will be understood, this would make it possible to connect 49 subscribers to the network. Usually a lesser number will be installed, so the subscriber numbers would go from 11 to 77, removing all numbers in which the ones digit is 8.9 or 0.

   As, however, the subscriber calling device will probably be of a normal type capable of producing up to ten pulses, it is possible that the subscriber makes a mistake and dials a number greater than seven, for example. 8. When this happens, it should be noted that when seven pulses have already been transmitted, the relays FR4 and FR3 are energized simultaneously in fact all the relays are energized, but this case is the only one or the relays FR4 and FR3 are excited together and this is therefore sufficient for the present aim.

   The eighth pulse can then be followed by the following circuit: earth, contacts 40, 41, 42, conductor 43, contact 51, conductor 52, contact 53, contact 68, contact 71, conductor 147, contact 148, conductor 46, the upper winding of relay BR, to the battery. The relay BR is consequently energized as described above, and besides giving the busy signal, it switches off the group of relays RRG1.

   Note that this happens whether the eighth pulse of a series is emitted in the first digit or in the second. It should be understood, of course, that the meter relay group and the storage relay group are both given as examples only, considerable changes can be made in the arrangements so that they can deal with different numbers of digits, either by increasing the number of relays, or by increasing the number of contacts on the relays. These arrangements could easily be developed by those skilled in the art who have fully understood the essence of the invention as it is disclosed in the example given.



   After having given a detailed description of the establishment of a communication, it will be useful to explain more particularly the operation and the circuit arrangements of the switches of

  <Desc / Clms Page number 23>

 line and main switches, and the connection between the groups of junction line relays and the fixed contacts of these switches.



   The fixed contacts of the calling subscriber line switch are shown in detail in fig.l. It can be seen that there are ten sets of contacts, the first set having access to the input end of the trunking line relay group TRG1, the third set to the input end of the trunking group. TRG2 trunk line relays, the fifth series at the input of the TRG3 trunk line relay group, the seventh series at the input end of the TRG4 trunk line relay group and the ninth series at the input end of trunk line relay group
TRG5, while the fourth series has access to the output end of TRG1, as has been shown, this series being, as can be seen, the series of contacts shown for the desoription of operation for the subscriber called No. 56.

   In fact, the fixed contacts of the line switch of each subscriber are connected in the same way as those of the line switch of the subscriber No.
22, but it will suffice to represent only the contacts in question in the case of subscribers No 22 and No, 56. The PA22 plunger arm is considered to be in position to close the contacts associated with the input end of TRg1, but it should be understood that it can be moved under the control of the main switch. cipal to operate any of the ten "series of contacts.



   Assuming that the plunger arms are normally in the position to operate the contacts associated with the input end of TRG1, the main switch wipers 606 and 103 will be in the position shown. When a subscriber, for example No. 22, makes a call, the plunger arm PA22 causes the closing of the contacts 17,18,19 &20; at contact 19, earth is connected to conductor 607 and therefore a circuit is closed as follows: earth, contact 19, conductor 607, contact 23, wiper 606, contact 608, lower winding from the LM locking magnet, to the battery. The LM locking magnet activates and releases the main switch shaft and closes contact 97.

   The main switch shaft rotates under the control of the

  <Desc / Clms Page number 24>

 spring and the centrifugal regulator, carrying with it all the free plungers, so that they pass in front of the fixed contacts in order, until the locking magnet is released. At contact 97 a circuit is closed for the OMR relay which removes the earth of the open main conductor OM, at contact 100, to prevent operation of plungers while the main switch is in action. When the wiper 606 reaches the next contact 609, it finds earth thereon and as a result the circuit for the locking magnet is retained and the main switch shaft continues to rotate.

   When the wiper 606 reaches the contact 610 associated with the input end of the group of trunking line relays TRG2 which will be assumed to be free, the contact 610 is then free of connection with the earth and the magnet. LM lockout de-energizes. As a result, the main switch shaft is stopped with the plungers facing the contacts associated with the input end of the TRG2 trunk line relay group.

   If no call has been started from the moment when the calling subscriber No.22 lifted his receiver until the moment when he completed the transmission of the number of the desired subscriber, the position of the diver will be as described and in Consequently to complete the connection of the calling subscriber No 22 with the desired subscriber No 56, only one advancement of the main switch shaft is necessary because it will be noted that the wiper 103 rests on the contact 611 when the earth is met by driver 95 upon completion of registration of the second digit of the desired subscriber number.

   As already described, the earth on conductor 95 energizes the SRM relay which, on contact 96, completes a circuit for the lower winding of the locking magnet, after which the main switch shaft rotates to that the wiper 103 reaches a contact connected to the battery potential, to produce the release of the main switch. Since contact 103 is the contact connected to the battery potential, it can be seen that the main oomnutateur must move only one notch.



  After the PA56 plunger arm has been actuated and contacts 137,138,139 connected to conductors 160,143,163, associated with the output of the TRG1 junction relay group, the logger is released and earth is removed from the conductor 95 The SRM relay de-energizes.

  <Desc / Clms Page number 25>

 te then and a new circuit is completed for the LM locking magnet as follows: earth, contact 6 @ 2, wiper 606 contact 608, the lower winding of the LM magnet, to the battery . The main switch shaft is therefore released again and advances until the wiper 606 reaches an ungrounded contact which may correspond to the input end of the trunk line relay group. TRG3 if this group is free.



   Usually, in the vast majority of cases, due to the comparatively small office capacity, only one subscriber sets up a call at a time and as the trunk line relay groups are taken up in order, the group The following junction line relays will usually be free and therefore the junction arrangement shown will minimize movement of the main switch shaft.

   Similarly, a call produced on the trunk line relay group
TRG2 will have the effect, if the relay group of trunk lines
TRG2 aura is free to align the plungers (after the call is established) in a suitable position to operate contacts associated with the outlet end of the group.

   trunk line relays TRG4j likewise in the case of calls made by means of the trunk line relay groups TRG3 and TRG4. In the case, however, where the group of trunking line relays TRG5 is taken into service for example by subscriber No 22, when the plunger arm PA22 is operating, the earth is connected, at the location of contact 620, to the conductor 621, and extends through the wiper 606, the contact 608, the lower winding of the LM locking magnet, towards the battery. The LM lock magnet operates and releases the rotary switch shaft which rotates the slider 606 in front of the grounded contact 622, until the end of its travel.

   When the MSA arm actuates the contacts 102 and 623, the contact 102 is open so as to prevent the worm-tool magnet from being de-energized while the wiper 103 is returning to its first position. Contact 623 closes the circuit of the trigger magnet TM, as follows: the battery the magnet TM, the contact 623, the contact 608, the wiper 606 (606) the contact 622, the earth. The trigger magnet TM energizes and

  <Desc / Clms Page number 26>

 is mechanically locked by the trigger 624.

   The TM magnet closes contacts 625 and 626, connecting earth to contact 626 to keep the LM locking magnet energized, and to contact 625 to energize the SM solenoid magnet so that the main switch shaft is returned to the position shown. When the main switch shaft has returned to the position shown in fig. 1, the MSB arm forces the trigger 624 out of the path of the spring controlling the armature of the trigger magnet TM, which then returns to the normal position.

   Contact 602 is closed and contact 623 opened by the MSB arm, while opening contacts 625 & 626 releases the solenoid magnet SM and the locking magnet LM, and if contact 23 is not connected to earth, the main switch stops in this position with the slider 606 on the contact 23. Otherwise, the movement of the main switch shaft starts again in the forward direction as described in the first place. .



   It is easily understood that if a group of trunk line relays were occupied, the main switch wipers would then always pass to the next free group of trunk line relays and this would imply, with the provision of trunk lines described, the movement of the main switch shaft to the end of its forward movement; the main switch shaft would then be returned to its first position as described above and would then move on to find the output end of the required group of trunk line relays,
The only difference in this case would be that SRM would be energized and the ground for the LM locking magnet would be held by means of contact 96.

   The operation of the SI solenoid magnet! and the TM trigger magnet would be the same as previously
With regard to fig. 14 & 15, it will be assumed that the subscriber Ne 22 starts a call. In this case, when only his receiver is going, a circuit is completed as follows for line relay LR22: earth, contact 14, subscriber line 13, the subscriber's equipment, conductor 12, contact 11, relay LR22, to the battery.

   Relay LR22 energizes and closes contact 15, which completes a circuit as follows: earth, contact 15 the OPM22 magnet pull coil, main conductor

  <Desc / Clms Page number 27>

 open, contact 700 to the battery. The OPM22 magnet is energized and forces the OPA22 plunger arm to close contacts 17,18,19 and 20; at the same time contacts 11 & 14 are open, which cuts the circuit of relay LR22 which de-energizes a little later.

   In the meantime, a retaining circuit has been closed for the lower winding of OPM22, by the earth connected to conductor 26, due to the operation of the release relay of the row relay group) the circuit of this release relay has been closed by the operation of relay LR, the circuit of this relay having been closed at contacts 17 and 18. At the same time, a circuit is completed passing through conductor 701 to the lower winding of magnet IPM22 , which is however ineffective since there are no contact springs which are controlled by IPM22 and the force exerted on the plunger arm is insufficient to make it work, although the current flowing in this winding is sufficient to keep it actuated when it has plunged.

   Connecting the earth to contact 19 completes a circuit for the OLM locking magnet as follows: earth, contact 19, conductor 704, wiper 703, OLM magnet, to the battery. The OLM magnet energizes and closes contact 702, which completes a circuit for the OOM relay which energizes and opens contact 700, which removes the battery from the open main conductor and thus prevents the operation of a other line switch such as OLS22 at this time.

   The OLM magnet also releases the main switch shaft, so that the 703 wiper switches to the next contact, and if this contact is free, the OLM circuit is open so that this relay de-energizes and locks the ar - bre of the main switch with the plungers facing the input end of the following group of junction line relays corresponding to fig. 2. If this trunk line were occupied, the earth would be found on contact 705 and the wiper 703 would advance one notch and so on until a free group of trunk line relays was found.

   If the slider 703 had originally been placed on the eighth or ninth contact and the subsequent contacts had all been occupied, or if it had been placed on the tenth contact, a circuit would have been completed as follows for the OTM trigger magnet: the battery

  <Desc / Clms Page number 28>

 the OTM relay, the contact 706 towards the earth on the contactor 703.



   By energizing, OTM completes a circuit for itself at contact 707 independently of wiper 703, and at contact 708 it has completed a circuit for the OSM solenoid magnet which consequently energizes and brings the plungers and wiper 703 back into the position represented. The OLM relay was also energized at this time and when the wipers are all returned to the position shown, the contact 706 is open, the OTM magnet is unhooked and the OLM relay is energized or not depending on whether the wiper 703 rests on a contact grounded.

   The QOM relay is energized continuously during the movement of the plungers so that the battery is lifted from the OM conductor during this period and for a short time thereafter} no line switch can therefore dive during operation of the main switch. If the trotter 703 is now resting on a busy contact, it continues hunting as before until it finds a free line.



   The remainder of the operation for establishing a call is carried out in the manner previously described with regard to freezes 2,4 & 5, and when the desired number, which will be assumed to be b6, is called, the the following operations take place, if it assumes that subscriber No 56 is free. In this case, a circuit is completed as follows when the CH1 relay de-energizes and the ACHI relay is still energized: earth, contact 73, contact 74, contact 86, SDR relay to the battery. By energizing, the SDR relay connects the SIR relay, via contact 108, conductor 107, contact 106 conductor 104, to contact 709 in the row of fixed contacts of the main switch IMS over which the wiper 710 passes.

   At the same time, earth is connected to conductor 95 at the location of contact 94, which completes a circuit for the ISR relay. The ISR relay energizes, and at contact 711 it connects the earth to energize the upper winding of the ILM locking magnet. The latter gets excited and allows the divers and the main switch slider to move forward a notch. In this condition, the battery is found on contact 709 by means of the winding of the SIR relay and as a result two windings of the ILM magnet are energized in opposition and the ILM relay is released while at the same time the SIR relay gets excited.



   It should be noted that the circuit of the lower winding

  <Desc / Clms Page number 29>

 ILM magnet neutralization goes through the contact 712 of the ISR relay and also through the contact 713. The purpose of this is to ensure that the locking magnet cannot be released when the ISM solenoid magnet is energized and the plungers are being returned to the starting position in fig. 15 with the slider 710 on the extreme right contact.

   When the SIR relay operates, a circuit is completed for the upper coil of the FR relay as follows: battery, upper coil of FR relay, contact 109, contact 188, contact 77, contact 134 , the contact 135, the conductor I36, the contact 127 of the UR relay, fig. 5, the conductor 133, the upper winding of the IPM 56 magnet, the conductor 723, the contact 715, of the line switch OLS56 , conductor 123, I2I contact of relay TD5, towards earth. As a result, the FR relay and the IPM56 magnet energize in this circuit.

   The IPM56 magnet now receives enough current to cause the plunger arm to dip and close contacts 724,725 & 726, so that conductors 160 and 163 are connected to conductors 161 and 162, respectively, and thence to the subscriber device No. 56; at the same time, the earth is connected by means of contact 725 in the following circuit: earth on contact 24, conductor 143, contact 725 to the lower windings of magnets IPM56 and OPM56.



  This serves to keep the plunger of the ILS56 line switch actuated while at the same time the OPM56 magnet energizes and opens the contacts 715,727 & 728. At contacts 727 & 728, it disconnects the line relay LR56 from between them. conductors I6I and 162 and thus prevent the plunger of the line switch OLS56 from being actuated when the called subscriber lifts his re-switch. At contact 715, it opens the circuit of the attraction coil, that is to say the upper winding of the IPM56 magnet and thus prevents any circuit from being completed for a relay such as FR from another recorder or the same recorder, if it was produced by another subscriber to establish a communication with subscriber No 56 while subscriber No 56 was still in contact with calling subscriber No 22.



   It will therefore be noted that if subscriber No 56 had been engaged before he was called by subscriber No 22 for an incoming call or an outgoing call, contact 715 would be open and consequently no circuit would be completed for the call. relaisFR, the result being

  <Desc / Clms Page number 30>

 that the occupancy relay BR would be actuated as described previously) when the ACHI relay finally allowed its armature to drop.



   It can therefore be seen that with the arrangement described, we obtain approximately the same results as in the case of the first arrangement, except that in this case it is possible to have up to ten conversation circuits. It should be noted that the conductor 104 associated with the group of row relays shown in FIG. 2 is connected to the second contact in the row of fixed contacts of the wiper 710 while the conductor 704 is associated with the first contact of the row on which passes the wiper 703. The oon nexions are represented in this way for ease of fapon that the operation of IMS can be described without the wiper 710 resting at the beginning on the chosen contact,

   but the best arrangement is probably that where the conductor 104 would be connected to the first contact in a manner analogous to the conductor 704 and furthermore all the conductors would be connected in the same order, that is to say the Inlet ends would be connected in the same order as the outlet ends.

   In the event that the slider 710 normally rests in a position beyond the contact it seeks, the slider 710 advances to the tenth contact position, after which the contact 713 is open and the contact 730 is closed; a circuit is thus completed as follows for the ITM trigger magnet: the battery, the ITM magnet, the contact 730, the contact 711 towards the earth, the ISR relay being obviously energized when a hunting operation is in progress . The ITM magnet energizes and closes a latch circuit for itself at contact 731, and at contact 732 it completes a circuit for the ISM solenoid which then energizes and returns all divers to normal.

   When this position is reached, the contact 730 is open and the contact 713 is closed, which allows the ILM locking magnet to be neutralized by the battery supplied by means of the wiper 710; the springs of the ITM magnet are therefore released, which opens the ITM latch circuit so as to allow this magnet to return to normal and the ISM solenoid to de-energize.

  <Desc / Clms Page number 31>

 



   Fig. 6 shows a general diagram and figs. 7,8,9,10,11,12 &
13 show detailed circuitry of a variant of the arrangement, which variant uses instead of the plunger type line switch line switches which are intended to rub on contacts and rotate at a single level. For this purpose, the row of fixed contacts of the line switch is divided into two parts so that when a subscriber calls, his line switch operates to choose a free line in the first part which will be called " A ", This gives it access to a group of TRG trunking relays which in turn, when taken in service, causes a recorder R to be connected to it by means of a recorder finder. RF.

   The subscriber then actuates his pulse emitter to launch a series of pulses depending, in number, on the call he wishes to produce. If he needs a call to the main office, he dials the number 0, which starts ten pulses, after which a circuit is completed to make the main group of MTRG trunk relays work. and that the switches of the switch associated with it turn and establish a connection with the group of relays of trunk lines TRG which is in service. When such a connection is made, the TRG trunk line relays are disconnected and the recorder is returned to normal so that it can be used for another call.

   The subscriber then activates his pulse transmitter to initiate a series of pulses corresponding to the number of the subscriber he wishes in the main office.



   If, on the contrary, the subscriber wishes to communicate with another local subscriber, he activates the recorder for two digits and. when the second digit is transmitted, if the line of the called subscriber is free, it forces the line switch of this subscriber to look in part "B" of its row of fixed contacts to find the end output of the group of trunks of relays whose input end has been taken in service by the calling subscriber, as a result of which a communication is completed between the local subscribers as will be understood more easily by studying individual circuits.

   Another circumstance which could arise is that a subscriber of the main office wishes to speak to a subscriber of the sub-office, in which case when a

  <Desc / Clms Page number 32>

 relay of the main group of MTRG trunk relays is taken into service, the line relay associated with it is hunting, not however in the first part of its row of fixed contacts, which can be called part "C" but in the second part of its row that we can call part "D"
The only difference between parts "C" and "D" is that a different test wiper is used, the test wiper chasing in this case to find an unoccupied group of trunk line relays and no, as before, a group of trunking line relays which have already received,

   according to the recorder associated with this group, a series of ten pulses. The recorder is taken into service in exactly the same way as if the call came from a calling subscriber, and the main office pulses are also stirred and recorded and the called subscriber's line switch (if this switch is free). ) is aotated to connect with part "B" of its row of fixed contacts, so that communication is completed as follows: through the junction line, by part "D" of the row of fixed contacts of the line switch associated with the main group of MTRG trunk relays, by a group of TRG trunk relays, by part "B" of the row of fixed contacts of the line switch of the called subscriber, to the called subscriber's device.



   We will now refer to FIGS. 7,8,9, IO, II, I2, I3 & 14 for the complete explanation of the operating circuits. Assume first that a local subscriber No.22 wishes to establish a communication with another local subscriber whose number will be assumed to be 56. He therefore lifts his receiver before making the call and thus completes the call. a circuit as follows: the battery, the LR22 line relay, contact 200, contact 201, conductor 202, through the subscriber's equipment and return through conductor 203 and contact 204 to earth .

   LR22 therefore energizes and closes contacts 205 & 206, simultaneously opening contact 207, which removes the earth from the lower winding of the CR22 change relay so as to signify that this line is busy if a call is extended to the calling subscriber's line switch.



   Contact 205 closes a circuit as it follows: the battery,

  <Desc / Clms Page number 33>

 
 EMI33.1
 mant M22, switch contact 208,1q? '- t8RHP205, contact 210, wiper P22, so that if wiper P22 rests on a grounded contact, magnet M22 operates and jerks the switch forward until an ungrounded contact is reached. By closing contact 206, LR22 has completed a circuit as follows: earth, contact 206, contact 211, interrupt relay COR22, contact 208, magnet M22 to the battery. However, the COR22 relay is short-circuited as long as the P22 wiper rests on a grounded contact.

   As soon as an ungrounded contact is reached, and it will be assumed that this contact corresponds to the group of trunking line relays TRG, relay COR22 is energized. On energizing it opens contacts 200 and 204 and closes contacts 212 & 213, which completes a circuit for the LRT line relay of the TRG trunk line relay group, as follows: battery, rolling top of the LRT relay, the conductor 214, the contact 215, the conductor 221, the contact 217, the wiper 218, the contact 212, the conductor 202, by the subscriber's equipment and return by the conductor 203 , the contact 213, the wiper 219, the contact 220, the conductor 222, the contact 223, the conductor 224, the lower winding of the LRT relay, to earth.

   The LRT relay therefore energizes and closes contact 225 which completes a circuit for the RRT release relay. The RRT relay energizes and closes contact 226, which connects the earth with the junction line release conductor 227 which extends through contact 228, conductor 229, test contact 230, the P22 wiper, the conta @ t 210, the uontaut 231, the uontaut 211, the relay COR22, the contact 208, the magnet M22 to the battery. This therefore serves to keep the relay COR22 energized after the switch 206 has been opened, due to the fact that the relay COR22, when energized, has opened the circuit of the relay LR22 to the switches 200 and 204.

   Relay COR22 also opens contact 232 which keeps the circuit of the lower coil of relay CR22 open after contact 207 has closed, which it does shortly thereafter. The LRT relay also opens contact 233 and closes contact 234, which has no effect at this time. The release relay RRT closes on energizing contact 226 and in addition it opens contact 235 and closes contact 236. It also opens.

  <Desc / Clms Page number 34>

 contact 237 and closes contact 238.
238 completes a circuit as follows: earth, contact 238, contact 239, conductor 240, contact 241 (fig.9), contact 242, searcher start relay FSR, to the battery. It has been assumed that the recorder shown in FIG. 9 is free.



   If he had been busy, instead of extending to the relay
FSR, a circuit would have been extended by contact 243 instead of contact 241, contact 246 to conductor 245; contact 246 is controlled by the FSR relay and serves simply to prevent two relays such as FSR from being energized simultaneously and the circuit extends to a conductor similar to conductor 240 for other recorders. Usually, two recorders are sufficient in an office of the expected size.



   If, however, there had been a third recorder, a similar circuit would simply have been extended to a third conductor similar to conductors 240 & 245 and depending on whether the first, second, or third recorder is free, the FSR relay associated with this recorder would have been put into action, the other operations being carried out in the manner which will be described below
For the moment, however, it can be assumed that there are no recorders available, in which case, when the calling subscriber begins to operate the dial and the LRT line relay de-energizes on the first impulse. , a circuit is completed as follows: earth, contact 226, contact 233, contact 247, contact 248, contact 323, occupancy relay BRT to the battery.

   The relay BRT therefore energizes and locks itself in the excited state at contact 249 in series with the earth on contact 226) it opens contact 250 and closes contact 251 which connects the signal d 'occupation, through the capacitor 252, with the conductor 214 and thence by the circuit previously described with the conductor 202 and the subscriber's apparatus, which informs the latter that he cannot obtain the communication with the subscriber he wishes. It therefore hangs up its receiver, which allows the LRT line relay to de-energize; the latter is followed shortly after by the release relay RRT, after which contact 226 is opened which allows relay OOR22 to de-energize. and the line relay LS22 is brought back to

  <Desc / Clms Page number 35>

 normal.

   Similarly, relay BRT of the group of trunking line relays TRG de-energizes when contact 226 is opened.



   If, on the other hand, the recorder shown in fig. 9 is free, the FSR relay is energized and the subsequent operation will now be described. The FSR relay opens contact 246 and closes contacts 253 & 254, which completes a circuit as follows: battery, MF magnet, switch contact 255, contact 254 contact 256, 'test 257, test contact 258, conductor 259, on which the earth rests if the group of trunking lines on which the rubbers of the RF recorder finder are located is not in a state. corresponding to the start of the call. If, for example, the TRG trunk line relay group were free, earth would be found at. using contacts 260 & 235.

   If, on the contrary, a group of junction line relays has taken a logger into service, earth will be found by means of contacts similar to contacts 236,654, 652 & 226, since it can be seen that the FTR relay is energized by the earth. re brought by contact 253 as soon as the group of TRG junction line relays is seized by the RF searcher. It is therefore evident that the MF magnet will operate intermittently until the RF recorder finder finds a group of trunking line relays, such as TRG in which the test contact is not placed. To the earth.



   It will now be assumed that the group of trunking line relays TRG is free, in which case a circuit can be drawn as follows: earth, contact 253, FOR relay, contact 264, contact 256, test 257, test contact 258, conductor 259, contact 236, contact 261, FTR relay to the battery.

   The FTR and FOR relays are consequently energized in series by this circuit and the FTR relay completes a locking circuit for itself by means of the contact 652 towards the earth located on the contact 226) by the closing of the contact. 625 it also places the earth on the test contact 258 by the following circuit: the earth, the contact 226, the contact 652, the contact 654, the contact 236, the conductor 259, the contact of Test 258, which marks the TRG trunk line relay group as busy for logger researchers.

   The FOR relay completes a latch circuit for itself in the way

  <Desc / Clms Page number 36>

 next: earth on contact 226, contact 652, contact
654, contact 236, lead 259, test contact 258, test wiper 257, contact 262, relay FOR, switch contact 255, MF magnet to battery. The MF magnet does not work in this circuit due to the resistance of the FOR relay. FOR also closes contact 263, which energizes the AFCR auxiliary relay. Note that the FOR relay opens contact 242 and closes contact 244, which completes a circuit between conductors 240 & 245 by means of contacts 241 & 244, so that another researcher can be activated. starts as soon as the FSR relay de-energizes when its circuit opens at contact 242.

   The earth was, however, removed from the searcher starting oonduo tor 240 by opening the contact.
239 when the FTR relay has operated.



   The subscriber then begins to form the first series of pulses on the dial which will consist of five pulses as he calls subscriber No 56. When the LRT relay is first de-energized, a circuit is completed as follows: earth, contact 226, contact 233, contact 247, contact 264, conductor 265, contact 266, wiper 267, contact 268, normal contact 269 of the TRS tens registration switch. Leaves low resistance TLRR, the magnet TM, towards the battery.



  The magnet TM and the low resistance relay TLRR therefore operate under the effect of the first pulse in the series.



  The TLRR relay is slow to unhook so that it remains energized during the whole pulse train, and at contact 270 it closes a circuit for the subsequent pulses of the series, as follows: by the wiper 271, that of the contacts engaged with this wiper when it is in an out of normal position, the contact 27u, the TLRR relay, the magnet TM, towards the battery, this circuit being independent of the normal contact 269. Consequently, the rubbers 271, 272 & 273 advance in jerks to the fifth out of normal position, in which they remain at the end of the series of pulses. At the end of the series of pulses, the TLRR relay de-energizes and a new pulse circuit is prepared for the next series of pulses.



   The subscriber then activates his calling device to transmit the second series of pulses which in this case will consist of

  <Desc / Clms Page number 37>

 six pulses and the first pulse in this series can be followed as follows: earth, contact 226, contact 233, contact 247, contact 264, conductor 265, fixed contact 266, wiper 267 , contact 268, slider 271 in the fifth out-of-normal position, contact touched by this slider, contact 274, low resistance ULRR relay, normal contact 275 of the unit registration URS switch, slider 276 , the UM magnet, towards the battery. The UM magnet operates accordingly under the effect of the first pulse and advances the wipers 276, 277 & 278 one step.

   The ULRR relay which is energized during the first pulse remains energized throughout the pulse train since it is slow to unhook. On energizing, during the first pulse, it closes contact 279 so that subsequent pulses pass through the following circuits: earth, contact 226, contact 233, contact 247, contact 264, conductor 265 , the fixed contact 266, the wiper 267, the contact. 268, the wiper 271, the sixth fixed contact on which the wiper rests, the contact 274, the ULRR relay, the contact 279, one of the out-of-normal contacts on which the wiper 276 can rest, the wiper 276, the UM magnet, towards the battery, As a result, the UM magnet advances the wipers 276,277 & 278 to the seventh position and the ULRR relay de-energizes at the end of the series of pulses, which closes the contact 280.



   A circuit is then completed as follows: the earth, the wiper 277, the seventh contact on which this wiper rests, the conductor 271, the contact 282, the contact 280, the contact 283, the MSR1 relay, towards the drums. Note that contact 28Z is located on relay MSR2 corresponding to relay MSR1, but associated with the other recorder, if it is assumed that there are only two recorders. If there are more of them, one could easily imagine a provision in which only one MSR1 relay would be actuated at a time. It should be noted that when energizing, relay MSR1 opens contact 284 to prevent relay MSR2 from energizing. However, it will be assumed that the MSR2 relay is not energized at this time; otherwise there will be a pause until the MSR2 relay is released.

   Relay MSR1, when energized, opens contact 284 and also closes the

  <Desc / Clms Page number 38>

 contacts 285,286,287 & 288. Contact 288 completes a circuit not for the slow acting relay SAR, but / relay / does not operate until a certain time has elapsed for a series of other operations; these operations will now be described.



   Note that a branch circuit is completed for the ICO pulse interrupt relay as follows: earth, contact 277, contact 282, contact 280, ICO relay, to bat-erie. The ICO relay energizes and opens contact 268, which cuts off the pulse circuit so that any new pulse can no longer influence the recorder.

   The ICO relay closes contact 289, which completes a circuit as follows: earth, MSRI relay contact 826, contact 289, wiper 267, fixed contact 266, conductor 265, contact
264, contact 247, contact 234, LRT relay being energized after the pulse train, contact 250, MPR relay, towards the battery The MPR relay, towards the battery: The MPR relay energizes and closes the contacts 290 & 291 and opens contact 292.

   By opening contact 292, it removes the earth from the output test contact
293, fig. 7, since it should be noted that the earth is normally
293 connected to the test contact / as follows: earth, contact 292, contact 294, conductor 295, to test contact 293, while at contact 291 it connects relay d 'CTR test of the line called at the test contact 293. The closing of contact 285 by the relay MSR1 completes a circuit as follows: the battery, the contact 285, the wiper 273, the sixth contact 296 on which the wiper 273 rests , the conductor 297, the lower winding of the CR56 relay, the contact 298, the contact 299 towards the earth, Note that this circuit depends on the fact that the called line is free and that it is open if the line relay LR56 or the interrupt relay COR56 is energized.



   In the first case, it will be assumed that the line is free and that the circuit cited above is completed in the manner described. As a result, relay CR56 energizes in this air and opens contact 300, which disconnects line relay LR56 from between conductors 301 and 302 of the subscriber line. Relay CR56 also closes contacts 303,304 & 307, which completes a circuit for itself at contact 304, independent of contact 299, and removes the short between the terminals / its top winding.

  <Desc / Clms Page number 39>

 laughing at contact 305.

   A circuit is then completed as follows by means of contact 303: earth, UTR relay, contact 287, wiper 278, seventh contact 308 on which this wiper rests, conductor 309, contact 303, contact 310, the LR56 relay, to the battery. The LR56 and UTR relays are therefore energized; the UTR relay opens contact 3II so that when the SAR relay energizes and closes contact 312, no circuit can be completed. When energized, relay LR56 opens contact 299 and closes contact 3I3j it also closes contact 314. A circuit is then completed as follows for magnet M56: the battery, magnet M56, contact d switch 315, contact 314, contact 316, contact 307, test wiper Q56, wiper which rests with the magnet on a grounded contact.



   The cause of this is that the contacts on which the Q56 wiper rests are grounded directly for the positions corresponding to the input end of a group of trunk line relays such as TRG, while the contacts corresponding to the output end of a group of trunk line relays are all connected to earth by relay contacts such as OTR and MPR, except for a calling group of trunk line relays, as on described} in fact the only test contact which is disconnected from earth at this time will be contact 293.

   The reason is that a relay such as MPR can only be energized in a group of trunk line relays which is associated with a recorder having its MSR1 relay energized, and only one relay such as MSR1 in the different recorders, can be excited at times. As a result, the magnet M56 energizes and turns the wipers 317,318, P56, Q56,318, until the wiper Q56 rests on the contact 293. When this happens, the magnet M56 ceases to function. and a circuit is completed as follows: earth, contact 313, upper winding of relay CR56, relay COR56, contact 315, magnet M56, to the battery.

   Relay COR56 trips in series with the upper winding of relay OR 56 in this circuit and opens contact 310, which disconnects line relay LR56 and relay UTR; however, this relay is slow to de-energize so that before it drops back to close contact 311, the CTR relay energized and opened the busy relay circuit.

  <Desc / Clms Page number 40>

 pation BRT. Relay COR56 closes contacts 329 & 330, which connects the subscriber loop to the output end of the trunk line group TRG1, ready for ringing current transmission. . The OOR56 relay also opens contacts 316 & 298.

   Opening of uontaut 316 prevents further operation of magnet M56 and opening of contact 298 opens the circuit of the lower coil of relay CR56, but relay CR56 remains energized by means of its upper coil in series. with relay COR56, because of the earth on the contact
313. Before relay LR56 drops out, a circuit is completed as follows by relay CTR: earth, contact 313, switch 320, contact 307, wiper Q56, contact 293, conductor 295 , contact 291, relay CTR, to the battery.

   The CTR relay is energized and at contact 319 it closes a locking circuit for relays CR56 and COR56 in series as follows: the battery, the magnet M56, the contact 315, the relay COR56, the coil. upper element of relay CR56, contact 320, contact 307, wiper Q56, test wiper 9R56, contact 293, conductor 295, contact 291, contact 319, to earth on contact 226 . On energizing, relay.CTR not only completes a latch circuit for relays CR56 and COR56 at contact 319 as described previously, but it also opens contacts 294 & 323 and closes contacts. 321,322 and 653.

   It should be noted that the effect of closing contact 319 is to maintain the earth potential by contact 291 or by contact @ 21 for the conductor 295 so that the test wiper 293 is maintained in connection. with earth potential to make it accessible to any other subscriber called the output end of the TRG trunk line relay group.



   At contact 322, relay CTR closes a circuit for the bell relay RRT, as follows: earth, contact 226, contact 322, contact 290, relay RRT, to the battery. The RRT relay energizes and completes a locking circuit for itself as follows: earth, contact 226, contact 335, contact 333, RRT relay to the battery and at contacts 325 & 326 it completes a circuit for ringing current, as follows:

   the ringing current generator by means of the contact 325, the conductor 327, the contact 328, the wiper 3I7, the contact 329,

  <Desc / Clms Page number 41>

   , the conductor 301, by the bell and the capacitor of the subscriber's equipment and return by the conductor 302, the contact 330, the wiper 318, the contact 331, the conductor 324, the contact 326, the resistance 336, towards the earth. At contact 656, the upper winding of the BBR relay is short-circuited and the lower winding of the BBR relay is shunted by a resistor, the relay is thus made slow and does not energize on alternating current. The subscriber's ringing tone therefore resonates intermittently in the well known manner.

   The CTR relay opens the
323 contact / to prevent a circuit from being closed for the BRT relay when the FTR relay or UTR relay drops out.



   At contact 653, a circuit is closed for the RRR recorder release relay which de-energizes and opens contacts 26I and 654, Earth is momentarily removed from conductor 259 by opening contact 654, which opens the contact circuit. locking of the SCR relay which de-energizes. At contact 263, relay FCr opens the circuit of relay AFCR which drops out and closes contacts 344 and 345, after which circuits are completed as follows: earth, wiper 267 which rests on the seventh contact, conductor 281, contact 343, upper coil of relay out of normal ONR, switch contact 344, magnet UM to battery. This has the effect that the UM magnet gradually turns the wipers 276, 277, and 278 to normal.

   Another circuit is completed as follows: earth, baby walker 262, contacts 345, OMR relay lower winding, switch contact 347, magnet TM, to battery. The TM magnet advances automatically in this circuit to bring the wipers by rotation to the eleventh contact.



  At the eleventh contact, a circuit is completed as follows: earth, wiper 272, tenth contact 348, contact 344, lower winding of the ONR relay, switch contact 347, magnet TM. The magnet TM therefore performs a new movement to advance the wipers 271, 272 & 273 in their normal position. It should be understood that the TRS and URS switches are of the type in which the wipers move in a continuous forward direction and have eleven contacts, one normal contact and ten out of normal contacts.

   The wipers have two diametrically opposed arms and the / .contacts are arranged

  <Desc / Clms Page number 42>

 in a semi-circle so that when a wiper arm leaves the last contact the opposite end of the wiper arm simultaneously engages the first contact} the ONR relay is energized to keep contact 243 closed as well while the magnets are in the process of returning the wipers to normal. As soon as the rubbers have returned to normal, the relay
ONR de-energizes and closes contact 241.

   Note that the purpose of closing contact 243 is to keep the conductor
240 connected to the conductor 245 until the recorder is in the position to return to normal} the FSR relay is made slow to produce the pull to prevent any possibility of this relay functioning due to a closing momentary in its circuit. It should be noted that the ICO and MSR1 relays return to normal when the contact 282 is open and the MSR1 relay opens the circuit of the SAR relay at contact 288 and the MPR relay circuit at contact 286.

   The FTR relay drops out shortly after the RRR relay is energized and replaces the earth on the esf contact sai 258 by means of the following circuit: earth, contact 226, contact 65I, contact 655, contact 236 , conductor 259, test contact 258, which marks the TRG trunk line relay group as occupied for record seekers.



   A ringing current branch circuit through resistor 336 extends to ground through conductor 337, the lower winding of the BBR rear bridge relay. The rear bridge relay does not energize on ringing current, but since the generator is supplied back in series with the battery, a direct current circuit is completed when the calling subscriber lifts his receiver, so that the BBR relay is set to energize as follows by means of its lower winding: earth, the lower winding of the BBR relay, the conductor 324, the contact 331, the wiper 318, contact 330, subscriber loop, contact 329, slider 317, contact 328, conductor 327, dontact 325, to the battery.

   At contact 335, the BBR relay opens the circuit of the RRT relay which goes off hook and, by closing contacts 338 and opening contacts 656 and 326, completes a circuit as follows for the BBR relay by its two windings: earth, l 'lower winding of the BBR relay, the

  <Desc / Clms Page number 43>

 conductor 337, conductor 324, contact 331, wiper 318, contact 330, conductor 302, by the subscriber's equipment, conductor 301, contact 329, wiper 317, contact 328, conductor 327, contact 338, conductor 339, the upper coil of the BBR relay to the battery. The BBR relay is therefore kept energized as long as the called subscriber's receiver is removed from the hook.

   The BBR relay closes contact 340 to complete the conversation circuit and contact 341 to short-circuit the capacitor 242 which was used to return the ringing circuit bool to the calling line. The conversation circuit can then be followed in thick lines from the calling subscriber to the called subscriber.



   When the subscribers have finished their conversation, the calling subscriber replaces his receiver and the LRT relay de-energizes. This is followed by the RRT relay which opens contact 226, which removes the earth of the trunk line release conductor and allows the CR56 and COR56 relays of the called subscriber's line switch to de-energize and to restore the line switch of the called subscriber to the normal state, and allows the relay COR22 of the line switch of the calling subscriber to de-energize and to restore the subscriber's switch to the normal state appellant.

   Removing the ground from the junction line release conductor allows the CTR relay to de-energize; at contact 653 the CTR relay opens the circuit of the RRR relay which de-energizes as a result, and the circuit of the junction line relay group is brought back to normal.



   The description will now be given of the case where the called subscriber was busy. In such cases, the UTR relay would not energize, as there would first be no circuit for the CR56 relay as a result of opening contact 310. As a result, the SAR relay would have energized. before the UTR relay and a circuit would have been completed as follows: earth, contact 312, contact 311, baby walker 349, contact 350, driver 351, contact 323, relay BRT to the battery . The BRT relay is energized, locks itself in the excited state on contact 249, opens contact 250 and closes contact 251, which connects with the subscriber calling the acoustic busy signal.

   The BRT relay also closes contact 662, which closes a circuit

  <Desc / Clms Page number 44>

 for the RRR relay which is energized to release the recorder in the manner already described. private shore
After having described how a subscriber of the office / can have access to another subscriber of the private office, it will now be described how a subscriber of a sub-office can have access to a subscriber of the main office. In this case, the connection is exactly the same as that described above, except that when the subscriber forms the first digit, instead of forming at the dial five, he forms ten and therefore advances the trotters 271,272 & 273 until the eleventh contact, in which case the wiper 272 rests on the contact 348.

   A circuit is then completed as follows: the earth, the wiper 272, the contact 348, the contact 350, the contact
280, contact 283, relay MSR1, to the battery. The other relay
MSR! is therefore excited (assuming that u @ / recorder is not marking at this moment) and closes contacts 285,286,287 and 288 as before. The following circuits are then completed: the battery, the contact 285, the wiper 273, the contact
352, the wiper 353, the contact 354, the conductor 355, the MTR relay to earth.

   The MTR relay therefore operates, closes contact 356, which connects earth to conductor 229 independently of the earth supplied by means of contacts 228 and 226; it also opens the contact 357, which disconnects the earth of the conductor 227. The relay MTR also closes the contact 359 to connect the switching relay SOR to the test contact 358 by means of the conductor 227. At the same time that the switch is made. operation of relay MTR and removal of the earth from contact 357, a circuit is completed as follows: earth, relay UTR, contact 287, wiper 278 in the normal position, normal contact 360, the conductor 361, contact 362 (fig.IO), contact 363, the upper winding of the LRM relay towards the battery.

   The LRM relay energizes in this circuit and closes a circuit for the RRM relay at contact 364. The RRM relay energizes and closes contacts 365 and 366; at contact 366 a circuit is completed as follows: test wiper 367, contact 368, contact 366, switch contact 369, magnet MM, to the battery.



   The magnet MM therefore operates intermittently as long as the wiper 367 rests on a grounded contact, which

  <Desc / Clms Page number 45>

 
 EMI45.1
 - - "" "..1f: a: 9 occurs until contact 358 of the TRG trunk line relay group is reached, since all other contacts similar to contact 358 are connected to the earth either by contacts like 370 & 357 if the trunk line relay group to which they are associated is free or engaged in a local connection, or by contacts like 365 and 374 if the trunk line relay group has been seized by a main trunk line relay group such as MTRG.

   When contact 358 is reached, due to the fact that it is in a special state determined by the fact that the MTR relay is actuated, the circuit for the STM switching relay becomes effective as follows: earth, contact 365, the STM relay, the 369 contact, the MM magnet, to the battery. The STM relay which is of high resistance, energizes alone in this circuit and opens contacts 363 and 368 and closes contacts 372,373 & 374. Closing contact 374 completes a circuit as follows: earth, contact 365, contact 374, the wiper 367, the contact 358, the conductor 227, the contact 359, the SOR relay, to the battery.

   The SOR relay energizes, opens contacts 2I5,228, & 223, which disconnects conductors 221,229 & 222 from conductors 214,227 & 224 respectively, thereby effectively isolating and releasing the TRG trunk line relay group. which consequently returns to normal in the manner described above and releases the associated recorder. The SOR relay completes a latch circuit for itself by means of contact 644 from conductor 227, contact 358, wiper 367, contact 374, contact 365 to ground. The SOR relay also opens contact 370, which prevents earth from being connected through contact 357 to test contact 358 when the MTR relay goes off, which it does immediately when the logger is turned off. released.



   A circuit is then completed for the LRM relay as follows, independently of its initial excitation circuit: the battery, the upper winding of the LRM relay, the contact 372, the wiper 376, the contact 377, the conductor 221, contact 217, wiper 218, contact 212, conductor 202, loop of the subscriber calling conductor 203, contact 213, wiper 219, test contact 220, conductor 222, contact 378, the contact 379, the contact 373, the lower winding of the LRM relay

  <Desc / Clms Page number 46>

 down to earth. The LRM relay is therefore kept energized and maintains the RRM relay circuit, which in turn maintains the STM relay circuit.

   The RRM relay, by energizing, completed a circuit for the ORM output relay, as follows: ground, contact 380, ORM relay, to battery. The ORM relay energizes to disconnect the DRM dry relay between conductors 381 and
382, to contacts 383 and 384 respectively, and at the same time it closes contacts 385 & 386 to complete a circuit through the junction line, which circuit can be followed as follows; the battery, the upper winding of the RCM delay coil, contact 387, contact 385, conductor 381, by a dry relay
DRE to the office, and back through conductor 382, contact 386, the lower winding of the RCM delay coil to ground.



   The se @ DRE relay, that is, the relay placed at the main office without battery or earth connections is therefore energized and prepared for receiving pulses, a description of which will be given later.



   Everything is now ready for pulse transmission to the main office and as a result the calling subscriber now operates his pulse transmitter to transmit a series of pulses corresponding to the first digit of the main office subscriber number. . With regard to the operation at the auxiliary office, each series of pulses produces the same effect and it will therefore suffice to describe only one series of pulses. When the LRM relay de-energizes on the first pulse, it opens contact 387, which opens the loop circuit through conductors 381 & 382 and allows the office DRE relay to de-energize.

   At the same time, it closes contact 388, which completes a circuit for the CHM change relay, as follows: earth, contact 388, contact 389, OHM relay to the battery. The CHM relay energizes and closes contacts 39C &391; at contact 391 it short-circuits the lower winding of the RCM delay coil, and at contact 390 it connects a shunt resistor to the upper winding of the RCM delay coil. This has the effect of increasing the efficiency of the pulse circuit.

   It should be noted that the following series of pulses does not differ appreciably, as regards the operation at the auxiliary office, from the operations.

  <Desc / Clms Page number 47>

   tions performed by the first series of pulses, so that the only operations which are still to be considered at this moment are the completion of the conversation circuit and the release.



   The conversation circuit is completed starting from the main office, by the conductor 318, the contact 385, the contact 387, the contact 392, the capacitor 393, the contact 372, the wiper
376, contact 377, conductor 221, and thence through the previously described circuit of the calling subscriber loop and return through conductor 222, contact 378, wiper 379, contact 373, capacitor 394, contact 386 to conductor 382, the battery being supplied to the calling subscriber by the LRM relay and to the called good by the main office battery.

   If a busy signal is received, its circuit can be followed in an analogous manner by means of the conversation circuit, while when subscribers hang up their receivers at the end of the conversation, the correct caller. causes the release of the LRM relay, which allows the ERM relay to de-energize, which in turn allows the release of the ORM & STM relays, thus returning the main group of MTRG trunk relays to normal.



   Removing the earth from conductor 227 by opening contact 365 allows the SOR relay and also the COR22 interrupt relay to de-energize. By de-energizing, SOR22 returns the line switch to normal so that everything is now ready to be used for another call.



   The operations which occur when the calling subscriber is in the main office and wishes to establish communication with a subscriber of the auxiliary office will now be described. Without entering at this point into a description of the operation which occurs at the main office and which will be described later, it will suffice to say that when the subscriber of the main office establishes a communication with a trunk line such as that of the conductors 381 and 382, the battery is sent forward to energize the DRM relay by means of the following circuit: the battery on the conductor 381, the contact 383, the coil of the DRM relay, the contact 384, the conductor 382, down to the main office. The DRM relay therefore energizes and closes contact 395, which closes a circuit for the RMT release relay.

   The RMT relay is energized and closes contacts 411,396 & 397. At contact 397 it completes

  <Desc / Clms Page number 48>

 it completes a circuit as follows: earth on a test contact such as 403 (assuming the associated group of trunk line relays are occupied test wiper 398, conductor 399, contact 400, contact 397, switch contact 369, magnet MM, to the battery, so operation depends on whether the baby walker 398 is based on a grounded contact. note that the wiper 398 has access to contacts such as 403 which are connected in multiple with contacts such as 230.

   The magnet therefore operates until an ungrounded contact is reached, and it will be assumed that it is contact 403, which is connected to conductor 229 and is therefore in multiple with contact 230, which indicates that the TRG junction line relay group is free.



   When this occurs, a circuit becomes effective for the COM relay as follows: ground, contact 396, COM relay, switch contact 369, magnet MM, to the battery. COM has a high resistance and therefore it only energizes in this circuit and opens contact 400 and closes contacts 404,
405 & 406. At contact 406 it connects the earth to conductor 399 so as to mark as occupied the test contact 403 and the test contacts such as 230. At contacts 404 & 405, it completes as follows a circuit between line trotters 376 & 379: the test rub 376, the conductor 407, the contact 405, the contact 408, the winding of the delay coil RTC, the contact 404, the conductor 409, the wiper 379.

   This is equivalent in all respects, with regard to the TTRG trunk line redo group, to a connection by a calling subscriber line switch, and it should be noted that contacts 377 & 378 are constantly multiple linked to contacts such as 217 and 220 respectively. When pulses come in from the main office, the DRM relay operates and opens contact 408; at the same time, it closes contact 410 which completes a circuit as follows: contact 410, contact 4II, relay llR, to the battery. Relay 11R energizes, closes contact 412, which shorts the RTC delay coil to improve pulses.

   The subscriber of the main office then dials two digits corresponding to the number of a subscriber of the local office and this operation should not be described since it is

  <Desc / Clms Page number 49>

 identical to the description given for the calling subscriber No. 22 connecting to the called subscriber No. 56. For example, in the present case, it will be assumed that the subscriber of the main office has called subscriber No. 56, and in in this case it receives the busy signal, as described previously, if the recorders are busy or if the called subscriber is busy, this signal being a sound which is transmitted by the conductors of the conversation circuit. .

   If a recorder is free, communication is extended to the called subscriber and if the latter is free a conversation circuit can be traced as follows: conductor 381, contact 383, capacitor 413, contact 408, contact 405, conductor 407;

   the wiper 376, the contact 377, the conductor 221, the contact 215, the conductor 214, the capacitor 252, the contact 341, the contact 338, the conductor 327, the contact 328, the wiper 317, the contact 329, the conductor 301, the device of the called subscriber, the conductor 302, the contact 330, the wiper 318, the contact 331, the conductor 324, the contact 340, the capacitor 414, the conductor 224, the contact 223, conductor 222, contact 378, wiper 379, conductor 409, contact 404 contact 415, capacitor 418, contact 384, conductor 382. This circuit extends to the main office by one ma - nière which is easily understood from the description given below and subscribers can then converse.

   When they are done talking, they hang up their receivers and the battery is removed from between conductors 381 & 382 at the main office, allowing the DRM relay to de-energize. The DRM relay goes off hook and opens an RMT circuit, which in turn goes off; the DRM relay also opens contact 408 which allows the LRT relay of the trunking line relay group TRO to go off hook, and the trunking line relay group TRG then releases as described previously. The RMT relay or the circuit of the COM relay, which allows this relay to deodorize and the connection is thus brought back to normal.



   A description will now be given of the devices located in the main office by means of which calls can be received from the sub office or extended to it. Fig.



  12 shows a diagram of the switches which are located at the main office and by means of which one can have the general understanding.

  <Desc / Clms Page number 50>

 hold of the communication establishment.



     When a call is received from the auxiliary office through a trunk such as TL, it is extended from the MRRG trunk group to the TLS trunk switch which has access to the first selectors in a manner. similar to the SLS subscriber line switch. As a result, the rush line switch is able to automatically switch on to find the first free selector, for example D, ready to receive pulses corresponding to the first digit of the number of the line. called from the main office. The establishment of a call is then identical to the establishment of a call by a subscriber of the main office.

   The first digit is received in the first selector D which is moved jerkily to the corresponding level and then automatically searches to find a second free selector such as E. The second selector operates under the effect of the second digit and then automatically searches for a connector such as F. The F connector operates under the effect of the next two digits to establish communication with the line of the desired subscriber in the main office. The operation of testing whether the desired line is busy or free, producing the signal for the called subscriber and closing the conversation circuit is carried out in the well known manner.



   If it is assumed that a subscriber of the main office wishes to have access to, a subscriber of the auxiliary office, when he lifts his receiver his SLS line switch automatically operates to choose a first free selector such as D. Both first series of pulses cause switches D & E to operate as above respectively. The second switch E then automatically chases to find a free junction line such as TL extending to the auxiliary office.

   In addition to the MTRG relay group, there is associated with the junction line a power supply group by the BFG battery by means of which the pulses of the calling subscriber which oonsist in the closing of a supply loop with battery of the main office towards the line of the calling subscriber, are transformed into pulses which consist in sending the battery forward, towards the auxiliary office, both at the beginning when the /, seizure in service and when

  <Desc / Clms Page number 51>

 continued during and after pulse transmission. The circuits by means of which the above operations can be carried out will be described with reference to FIGS.



  He and 13.



   Assume that a subscriber of the sub-office wishes to call a subscriber of the main office. It then forms on the dial the number 0 as described above, after which it is connected with the junction line whose conductors are designated by 38I, 382, and as described above. , it supplies the battery through these conductors before the transmission of pulses corresponding to the desired subscriber number of the main office. A circuit is then completed as follows: the battery, the upper winding of the RCM delay coil, (fig. 10), the contact 387, the contact 385, the conductor 381 of the TL junction line, the con - tact 500, relay DRE, contact 501, conductor 382, contact 386, the lower winding of the RCM delay coil to earth.

   The DRE relay energizes in this circuit and closes oontaots 502 & 503, which completes a circuit for the RRE release relay and prepares a circuit for the LRE relay. The RRE release relay energizes and closes contacts 504,505,506. At contact 504, it prepares a circuit for the CRE relay. On contact 505 it places the earth on conductor 507 to prevent the junction line from being taken into service by a switch such as E, and on contact 506 it completes a circuit as follows: for the LRE relay: the battery, the LRE relay, contact 508, contact 506, contact 509, RCE delay coil, contact 502, contact 510 to earth.

   The LRE relay energizes and closes the contacts 5II, 5I2. At contact 511 it connects the test wiper 513 to the magnet ME by means of the following circuit: the wiper 513, the contact 514, the contact 511, the switch contact 515, the magnet tests ME, to the building. If the first selector is occupied, the contact 516 on which the wiper 513 rests is connected to earth and the magnet ME moves the wipers 513,517,518 one step forward.



  This continues as long as the selectors tried are oc- cupied.



   It will be assumed that the selector D is free and that consequently there is no earth on contact 516. Consequently, the COE relay is energized in the circuit following the earth, contact 512,

  <Desc / Clms Page number 52>

 COE relay winding, switch contact 515, ME magnet, to battery. The COE relay only energizes in this eir ouit because of its high resistance and opens contacts 508 and
510, thus disconnecting the line relay LRE and closing the contact 521, which disconnects the test wiper 513 from the magnet
ME and connect it to earth at contact 512 so as to mark selector D as occupied during the interval that elapses before the release relay energizes in selector D.

   Relay
COE also closes contacts 519,520, which extends the line circuit to the first selector whose line relay is energized as a result of the already described closed circuit passing through the RCE delay coil. The selector release relay energizes in a manner well known in this branch of industry and binds earth to test contact 516 which makes the first selector busy and provides a hold circuit as follows for the COE relay: earth on contact 516, wiper 513, contact 521, COE relay, switch contact 515, magnet
ME, to the battery. This circuit is completed before the relay
LRE drops back and opens contact 512.



   The series of pulses corresponding to the first digit is then transmitted to the number of the desired subscriber. As already described, the battery sent forward by conductors 381 &
382 of the TL junction line is interrupted intermittently and the DRE relay drops for each pulse. On falling, it opens contact 502, which opens the selector D line relay circuit in a manner similar to interrupting the line circuit when a calling subscriber operates his calling device. The DRE relay also closes contact 522 and thus completes a circuit for the CRE relay, as follows: earth, contact 522, contact 504, CRE relay to battery.

   The CRE relay energizes and closes contact 523, which completes a circuit between wipers 508 and 517 independently of the RCE delay coil, Eraser follows: wiper 517, contact 520, contacts 502,523,506,519, the wiper 518, so that the impedance of the impulse circuit is reduced to a minimum during the operation of the dial.



   The remaining series of pulses is repeated in a similar manner to the second selector E and connector F, and the comunica-

  <Desc / Clms Page number 53>

 tion is completed in the well known manner if the called subscriber. is free and a busy signal is given if the called subscriber is busy. To produce the release, as previously described, the battery is removed from between conductors 381,382 when the calling subscriber hangs up his receiver and consequently the DRE relay de-energizes. The RRE relay also de-energizes while opening the contact 502 releases the TLS, D, E and F switches. The RRE relay opens the 505 contact and thus makes the TL trunk line accessible to subscribers in the main office. .



   It will now be assumed that a subscriber of the main office wants to connect with a subscriber of the auxiliary office. The transmission of the first two digits operates a first selector and a second selector in the well known manner; from the second selector, one has access to trunk lines such as TL and one will assume that TL is the first of a group found free.

   Consequently, it will be assumed that the wipers 524,525 & 526 are respectively connected to the conductors 530,507 & 532 which terminate at the battery supply group BFG (fig.ll). A ! The circuit is then completed for the LRB relay as follows: the battery, the upper winding of the LRB relay, the conductor 530, the contact 527, the, wiper 524, by the E & D selectors and the subscriber loop to the wiper 526, contact 529, conductor 532, the lower winding of the LRB relay, to earth. The LRB relay energizes and closes the contacts 533 and 534, which completes a circuit for the RRB relay and closes a point in a circuit which will be completed in the following as will be described now.



   The RRB relay closes by energizing the contact 535, which links the earth to the conductor 507, the earth extending backwards towards the contact 528 to make the TL junction line in inaccessible; the earth potential also extends forward towards FIG. 13 by completing a circuit for the TRE relay which can be traced as follows: earth, contact 535, conductor 507, contact 536, relay TRE, relay COE, contact 515, magnet ME to battery) the COE & TRE relays are energized alone in this circuit. However, the operation of the COE relay has no effect since the celais TRE opens the, con-

  <Desc / Clms Page number 54>

 tacts 500.50I, which disconnects the DRE relay and prevents contacts 506 & 502 from closing and extending a circuit through the TLS switch.

   At contacts 537 and 538, the TRE relay transfers the connection from the junction line of the DRE relay to the conductors 539,540 so that the battery is now supplied to the auxiliary office by the following circuit: the battery, the winding RCB relay top, contact 538, contact 537, conductor 381 to the auxiliary office, DRM relay winding, to main office through conductor 382, contact 538, conductor 540, contact 534, the lower winding of the RCB delay coil, towards earth.



   This therefore causes the DRM relay to be excited at the auxiliary office, with the results already mentioned.



   During the pulses of the next two digits which correspond to the subscriber's number in the auxiliary office, the 'CRB relay is energized by contacts 541,542, at the first pulse and remains energized for a series of pulses and it short-circuits the lower winding of the late ROB coil to contact 543 so as to increase the efficiency of the series of pulses.

   The further establishment of the call will result from the description given previously, and if the called subscriber, for example subscriber No. 56, is free, a conversation circuit can be drawn as follows: the device of the calling subscriber, the line switch SLS, the D & E selectors, the wiper 524, the contact 527, the conductor 530, the capacitor 660, the conductor 539, - the contact 537, the conductor 381, the contact 383, capacitor 413, contact 408, contact 405, conductor 407, wiper 376, contact 377, conductor 221, contact 215, conductor 214, capacitor 252, contact 341 , contact 338, conductor 327, contact 328, baby walker 317, contact 329, conductor 301, the called subscriber's device, conductor 302, contact 330, wiper 318, contact 331,

   conductor 324, contact 340, capacitor 414, conductor 224, contact 223, conductor 222, contact 378, wiper 379, conductor 409, contact 404, contact 415, capacitor 416, contact 384, conductor 382, contact 538, conductor 540, contact 534, capacitor 661, conductor 532, contact 529,

  <Desc / Clms Page number 55>

 the 526 slider, E & D selectors, line switch
SLS, to the device of the calling subscriber. When the subscribers have finished their conversation, they reooroohent their receiver and the call is undone in a manner which will be easily understood from the description given above.



    Claims.



   -------------------
1. A telephone system in which pulses are transmitted by a different path from that by which the conversation current is established, characterized in that the selection of a switch and the extent of operation of the switch to supplement the current of the conversation. conversation are produced by means of conductors each of which is common to several of these switches,
2. A telephone system using non-digital switches controlled by a main switch, in which the circuits of the main switch are so arranged that the switches under its control can be arranged to establish communication with either a labral line in a group or with a line chosen beforehand.



   3. A telephone system employing digital switches controlled by a main switch, in which the main switch is intended to be controlled as a result of the operation of a switch under its control for selecting a line. free, or to be ordered following the selection of a switch under its control, to allow the chosen switch to establish a connection with a line chosen beforehand.



   4. A telephone system employing non-digital switches controlled by a main switch, in which the main switch is intended to be operated either immediately before operation or immediately after operation of a switch located below. its command, depending on whether the line with which the communication must be established is a predetermined line or a free line of a group.

** ATTENTION ** end of DESC field can contain start of CLMS **.


    

Claims (1)

5. A telephone system in which a non-digital switch associated with each subscriber line and controlled by a main switch is intended to be actuated to establish a connection with a previously selected free line during a call. call <Desc / Clms Page number 56> outgoing and to establish communication with a selected line already in service during an incoming call. 6. A telephone system in which conver sation connections are made by means of line switches having their fixed contacts connected together to form a conversation circuit, characterized in that the line switches are arranged in a selectable manner. in advance a free talk circuit - it is taken up at the start of a call, and then a- after the called subscriber's number has been transmitted, the line switches are actuated to select the circuit. conversation in service. 7. A telephone system in which plunger-type line switches, under the control of a main switch, are arranged to select a free talk circuit, the line switch being under the control of a main switch. a calling subscriber being intended to take up this conversation circuit to which is temporarily associated a relay register on which the number of the called subscriber is registered, after which the line switches are actuated to choose the conversation circuit in service and the called subscriber's line switch is quoted to connect to the conversation circuit and establish communication. 8. For use in a telephone system, a relay recorder consisting of a series of relays in which one relay is energized and a previously operated relay is de-energized on each successive pulse, and after the last relay in the series is energized, it is set so as to be kept energized while the other relays are intended to be re-energized by means of subsequent pulses, in substance as oi-above. 9. For use in a telephone system, a relay recorder consisting of a series of counting relays less than the maximum number of pulses in a series to be recorded = .. a series of smaller number of storage relays the maximum number of pulses in a series to be recorded, and a means of transferring the first recorded series of pulses from the counter relays to the storage relays. 10, A telephone system in which communications in a branch office are established by means of a telephone switch. <Desc / Clms Page number 57> calling subscriber line and called subscriber line switch, characterized in that when a call is started for a subscriber of the main office a line switch associated with a trunk line terminating at the main office is ac- tionn and communication is completed through the calling subscriber line switch and the trunk line switch. He. A two-way trunk line terminating in the mobile terminals of a single switch which is intended to be operated to extend calls going in either direction. 12. A group of trunk line relays, which is accessible by means of a series of conductors to the line switch of a calling subscriber and by means of another series of con-. duoteurs to the line switch of a called subscriber, and which is also accessible by means of a third set of conductors, to a line switch associated with a trunk line terminating at another office. 13. A busy signal device, in which whenever pulses are produced and conditions are unsuitable for receiving pulses, the pulse circuit is extended to a signal generating device of occupation to cause the operation of it. 14. A telephone system employing plunger type line switches, in which two line switches are associated with each line, one of these switches being operated for outgoing calls and one for incoming calls. 15. A telephone system according to claim 14, wherein contacts associated with one of the line switches are actuated regardless of which line switch is in operation. 16. A telephone system according to claim 1, wherein the switch is set in motion at the same time as several other switches and the selection of the switch to be operated does not become effective until after the extent of movement of these switches has been reached. been determined. 17. A telephone system according to claim 1, wherein the switch is first chosen and then moved from the am. <Desc / Clms Page number 58> desired fullness regardless of the operation of other switches. 18. A telephone system according to claims 1, 16 and 17, wherein the selection of the required switch is produced by choosing a conductor from each of the two groups of conductors, each conductor of which is connected to a different set of switches. 19. A telephone system according to claim 18, wherein the conductors of one group are normally disconnected and are not connected until after an operating current has been transmitted by a conductor of the other group. 20. A relay recorder according to claim 9, wherein the second series of pulses are stored in the counter relays and wherein the counter relays and the storage relays commonly control operation. 21. A trunk line relay group according to claim 12, in which the trunk line relay group has been associated with a register to store the desired subscriber number. 22. A trunk line relay group according to claims 12 and 21, in which the establishment of a connection with the called subscriber's line switch causes ringing current to be transmitted by means of these. conductors. 23. A trunk line relay group according to claim 21, in which establishing a connection with the trunk line switch automatically releases the recorder. 24. A trunk line relay group according to claims 21 and 23, in which the recorder is associated with the trunk line relay group at the start of a call and is released when a line is started. trunk is called or when a busy signal is given. 25. A busy signal device according to claim 13, in which the pulse circuit is extended to the busy signal device, until a moment when an apparatus is pulsed. is taken into service @ 26. A busy signal device according to the claims <Desc / Clms Page number 59> EMI59.1 'like 13 and 25, in which the' circuit do im'P21sion - egt'prolong'é,. , by the device operating under the effect of the pulses, to the busy signal device when the maximum number of pulses in a series to which the device in question is intended to respond have been received. 27. A busy signaling device for use in a telephone system as claimed in claim 19, wherein no current has passed through one of the normally disconnected conductors after a determined interval while they are at - should be connected causes a circuit to be closed for a busy signal device which then sends a busy signal to the calling subscriber. 28. Telephone systems in substance as described above and as represented for the purposes annexed.