US1944694A

US1944694A - Telephone system

Info

Publication number: US1944694A
Application number: US623083A
Authority: US
Inventors: Edward S Peterson
Original assignee: Associated Electric Laboratories Inc
Current assignee: Associated Electric Laboratories Inc
Priority date: 1932-07-18
Filing date: 1932-07-18
Publication date: 1934-01-23
Anticipated expiration: 1951-01-23

Description

Jan. 23, 1934. E. s. PETERSON 1,944,594

TELEPHONE SYSTEM I Filed July 18, 1932 2 Sheets-Sheet l R & :Q

dward 5. Pm

Jan. 23, 1934. E, s, PETERSON TELEPHONE SYSTEM Filed July 18. 1952 2 Sheets-Sheet 2 -l'1mlfi Edward 5P2 arson Patented Jan. 23, 1934 UNITED STATES PATENT OFFICE TELEPHONE SYSTEM Application July 18, 1932. Serial No. 623,083.

20 Claims.

The present invention relates in general to telephone systems, but is concerned more particularly with operator controlled magneto exchange (O. C. X.) telephone systems, in whichcommunications between two subscribers are established by manual operators from a remote or distant control point.

More in particular, the present invention rev lates to a telephone system wherein an operator at a central office may control the switching equipment in an outlying exchange or rural office terminating local battery magneto lines either to establish connections between two subscribers in the rural oflice or to establish connections to the central or main oflice.

One object of the invention is to provide a cheap but nevertheless efficient unit for small rural communities that heretofore have been without any communicating service because the number of subscribers desiring service did not warrant the installation of a switching exchange.

The switching unit in the present invention is arranged to take care of ten subscribers lines and is controlled over a single trunk line from a distant central ofiice by a manual operator. The switching unit may easily be mounted in an iron box and mounted on a telephone pole at the central point in the community to be served. The unit operates on a 12-volt storage battery that is floated by the distant central ofiice battery over the trunk line. The operator in the manual exchange transmits ringing current over the trunk line to signal the calling subscriber if necessary and also to signal the wanted subscriber.

Another object of the invention is the provision of improved circuit arrangements, whereby the control of the magneto exchange by the operator at the central oflice may be brought about in a thoroughly reliable manner, while the numher of conductors required between the two exchanges over which the operator controls the setting up of connections between subscribers in the magneto exchange is reduced to a minimum.

Description of drawings ring now to the drawings, they show by means ofthe switching equipment shown to the left of the trunk line TL in Fig. 2 comprises the operator controlled magneto exchange. The local battery magneto substations T1 and T2 terminate in the finder switch FS which is operated to find a calling subscribers line. The. connector switch CS, which is part of the operator controlled exchange equipment, is directively positioned by impulses from the manual exchange operators position to select a wanted subscribers line. The finder switch FS and the connector switch CS are of'the well-known rotary type whose wipers are advanced upon the release of their respective stepping magnets. Fig. 2 shows the equipment in the manual exchange and comprises the operators trunk circuit TC, the answering jack J, the operators cord circuit CC, and the calling device CD by means, of which the operator at. the manual exchange controls the switching equipment in the operator controlled exchange by plugging in jack J1.

Detailed description A detailed description of the operation of the apparatus shown will now be given. It will be assumed that the subscriber at substation T1 desires'to establish a connectidn with the subscriber at substation T2.

The subscriber at substationv T1 in order to signal the operator at the manual exchange, operates his handzgenerator to transmit ringing current over his line, after which he removes his receiver so as to be able to converse with the operator when she responds. Responsive to the ringing current transmitted .over line conductors 1 and 2, relay 3 operates and completes a locking circuit for itself at armature 6 and its front contact. Relay 3 remains locked in its energized po-' sition until the operator answers the call. At armature '7 and its front contact, the relay 3 grounds the common start conductor 76 thereby causing the energization of start relay 1'1 and at armature 5 and its front-contact groundsa bank contact of the finder switch FS to mark the-calling line.

It may be well to mention at this time that if some other subscriber inthe O. C. X. has previously initiated a call, the finder switch FS will not be available for extending the call from SUbSlifl'? tion T1 to the operator at the manual exchange. However, when the switching equipment in the O. .C. X; is released by the calling subscriber, the finder switch will immediately operate, since the relay 11 will be maintained energized from the ground at armature '7 of the line relay3 and-:will

hunt for the line marked by ground at armature 5 and its front contacts.

It will be assumed, however, that the equipment in the operator controlled exchange is idle. As soon as start relay 11 is operated, it closes a circuit at armature 23 and its front contact for the rotary magnet 8 of the finder switch FS. The circuit for operating rotary magnet 8 is as follows: battery, winding of magnet 8, armature 23 and its front contact, armature 27 and its resting contact, armature 45 and its resting contact, conductor 67, armature 111 and its resting contact, to ground. At armature 74 and its front contact, magnet 8 completes an energizing circuit for the upper winding of relay 13 which responds and at armature 27 and its resting contact opens the initial energizing circuit for the magnet 8. The magnet 8 deenergizes, thereby advancing wipers 5457 one step into engagement with the next set of bank contacts, and at the same time opens the circuit for the upper winding of relay 13 at armature 74 and its front contact. If the bank contacts encountered by the wipers 5457 are not the contacts to which the line of substation T1 is connected, magnet 8 will again energize, as soon as relay 13 falls back, over. the previously traced circuit. The interaction between magnet 8 and relay 13 continues and the wipers 54-57 are advanced each time the circuit of the magnet 8 is opened until the wiper 55 encounters the bank contact marked by the opera tion of the calling subscribers line relay. When this occurs, the following circuit is completed from ground, armature 5 and its front contact, wiper 55, conductor 65, armature 110 and its resting contact, conductor 64, lower winding of relay 20, 'lower winding of relay 13, to battery. Relay 13 is maintained energized over this circuit to prevent further rotation of the wipers of the finder switch FS. Relay 20 energizes and completes a locking circuit for itself over its upper winding over a circuit from battery, upper winding of relay 20, armature 47 and its front contact, armature 40 and its resting contact, to ground. At armature 46 and its front contact, relay 20 closes a circuit from ground, armature 40 and its resting contact, armature 46 and its front contact, conductor 68, armature 112 and its resting contact, winding of slow-to-release relay 104, to battery. Relay 20 opens another point in the circuit for magnet 8 at armature 45 and its resting contact, it short circuits the lower or holding winding of line relay 3 over a circuit including armature 44 and its front contact and wiper 56 of the finder switch FS, thereby causing the line relay 3to restore to normal, it prepares a circuit for relay 22 at armature 43 and its front contact, and at the front contacts of armatures 42 and 48 it extends the calling subscribers line over conductors 62 and 75, respectively, to the left-hand winding of repeating coil R. Responsive to the restoration of line relay 3, the upper winding of the relay is again bridged across the calling subscribers line conductors 1 and 2, and at armature 7 and its front contact the operating circuit for start relay 11 is opened.

It should be noted that relay 102 in the O. C. X. is energized in series with relay 122 in the manual exchange over a circuit including the 24-volt manual exchange battery, the two conductors of the trunk line TL in parallel and the 12-volt O. C. X. battery. Responsive to the operation of relay 104, the battery charging circuit of the O. C. X. which includes the winding of relay 102 isopened at armature 114 and its resting contacts. Relay 102 in the O. C. X. and relay 122 in the manual exchange deenergize. Relay 102 upon falling back closes an energizing circuit for relay 103 as follows: from battery, winding of relay 103, armature 106 and its resting contact, conductor 69, armature 40 and its resting contact, to ground. At armatures 109 and 113 and their respective front contacts, relay 103 extends the conductors 115 and 116 of the trunk line TL to the right-hand winding of the repeating coil R and at the same time additional points in the charging circuit are opened at the normally closed contacts controlled by armatures 109 and 113 and their respective front contacts. At armature 112 and its resting contact, relay 103 opens the circuit for the S10W- to-release relay 104 which upon restoring again prepares a circuit for relay 102 at armature 114 and its resting contact. At armature 111 and its resting contact, relay 103 opens an additional point in the circuit for magnet 8, and at armature 110 and its front contact it prepares a circuit for relay 22. The closing of armature 107 and its resting contact, and the opening of armature 108 and its front contact by the release of relay 102 has no effect at this time.

Referring now to relay 122 in the manual exchange which falls back responsive to the operation of relay 104 in the O. C. X. As soon as relay 122 falls back, it completes a circuit at armature 134 and its resting contact for energizing relay 123. At armature 137 and its front contact, relay 123 completes a locking circuit for itself and at the normally closed contacts controlled by the front contacts of armature 137 it opens its initial energizing circuit. At armature 136 and its resting contact, relay 123 disconnects relay 122 from the trunk conductors and at armature 138 and its front contact it completes a circuit for lighting the calling lamp L to signal the operator at the manual exchange. In addition, a circuit is completed to a delay alarm circuit,

which starts to function and gives the operator an audible signal if she does not answer the call Within a predetermined interval of time.

When the operator at the manual exchange notes the lighted lamp L, she inserts the plug of her cord circuit CC into the answering jack J. Responsive to the plugging in at the answering jack J, contacts 139 of the jack springs are closed thereby completing an energizing circuit for relays 118 and 120. Relay 119 operates responsive to the energization of relay 120. At armature 127 and its front contact, relay 118 places a shunt around the condenser in the righthand winding of the repeating coil R1 thereby preparing the supervisory circuit in the cord circuit CC. At armature 126 and its front contact, relay 118 prepares a circuit for connecting battery by way of the impedance 121 and the normally closed contacts controlled by armature 135 to the upper trunk conductor, and at armature 12S and its front contact, it prepares a circuit for connecting battery by way of relay 117 and ringing key K2 to the lower trunk conductor.

Referring again to the operation of relay 119. At armature 130 and its resting contact, relay 119, opens the locking circuit for relay 123, at

armature 131 and its front contact it opens the circuit to the delay alarm circuit, at

armatures

129 and 140 and their respective front contacts it connects battery from the impedance 121 to the upper line conductor and connects battery from relay 117 to the lower line conductor. At the resting contacts of

armatures

129 and 140, additional points in the charging circuit are disconnected. The calling lamp L is extinguished responsive to the deenergization of relay 123.

When battery is connected to the upper trunk conductor by the operation of relay 119, the following circuit is closed; from battery, winding of impedance 121, armature 126 and its front contact, normally closed contacts controlled by armature 135, armature 129 and its front contact, upper left-hand winding of repeating coil R1, conductor 115 of trunk line TL, armature 109 and its front contact, upper right-hand winding of repeating coil R, conductor 72, winding of relay 16, to ground. When battery is connected to the lower trunk conductors by the operation of relay 119, the following circuit is closed; from battery, relay 117, armature 128 and its front contact, normally closed contacts of key K2, armature 140 and its front contact, lower lefthand winding of repeating coil R1, conductor 116 of the trunk line TL, armature 113 and its front contact, lower right-hand winding of repeating coil R, conductor 70, armature 28 and its resting contact, armature 53 and its resting contact, conductor 71, winding of relay 101 to ground. Relay 16 energizes in series with impedance 121,

and relay 101 energizes in series with relay 117.

At armature 125 and its resting contact, relay 117 opens a point in the supervisory circuit ofthe operators cord circuit CC and relay 101 opens a point in a signalling circuit at armature 105 and its resting contact, the function of which will be explained hereinafter. Relay 15 operates responsive to the operation of relay 16 and prepares a circuit for the magnet 9 of the connector switch CS at armature 32 and its front contact, prepares a circuit for relay 18 at armature 33 and its front contact, operates relay 19 over a circuit including armature 31 and its front contact, and at armature 30 and its front contact maintains the conductor 69 grounded. At armature and its resting contact, relay 19 opens a point in the circuit for grounding conductor 69 which is now maintained grounded from armature 30 and its front contact, and at armature 41 and its front contact it completes a locking circuit for itself over conductor 73 to ground at armature 107 and its resting contact.

If the subscriber at substation T1 has removed his receiver and has waited for the operator at the manual exchange to respond, the subscriber may now converse with the operator at the manual exchange. The operator at the manual exchange may either extend the connection for the subscriber at substation T1 to a wanted subscriber in the manual exchange or if the subscriber at the substation T1 desires to talk to anothersubscriber connected to the O. C. X. the operator dials back over the trunk to set the connector switch C5 to the wanted subscribers line.

If the subscriber at substation T1 has not removed his receiver, the operator at the manual exchange may signal the subscriber by operating her ringing key K. The circuit operation that takes place when the operator signals a subscriber that has initiated a call will now be described.

When the operator at the manual exchange operates her key K2, the circuit over conductor 116 of the trunk line TL that includes the winding of relays 117 and 101 is opened at armature 125and its resting contact. Relay 117 falls back and again closesthesupervisory circuit inthe operators cord circuit CC, and relay 101 upon falling back prepares a circuit for the A. C. relay 14 at armature 105 and its resting contact. At the front contact of the key K2, ringing current is connected to the lower line conductor 116 to operate the A. C. relay 14 in the O. C. X. over the following circuit: from battery, generator GEN. front contact of key K2, armature 140 and its front contact, lower left-hand winding of the repeating coil R1, conductor 116 of the trunk line TL, armature 113 and its front contact, lower right-hand winding of the repeating coil R, armature 105 and its resting contact, conductor 63, winding of A. C. relay 14, condenser, to ground. At armature 28 and. its resting contact, A. C. relay 14 relays a point in the circuit of relay 101, and at armature 29 and its front contact, completes an energizing circuit for relay 21. The opening of the resting contacts of armatures and 51 by relay 21 has no effect at this time. At armature 49 and its front contact, relay 21 connects the upper line conductor of the calling subscribers line to the conductor 63 over which the ringing current is being transmitted, and at armature 52 and its front contact grounds the lower line conductor of the calling subscribers line. The ringing current is now transmitted by way of armature 49 and its front contact, armature 42 and its front contact, Wiper 54 of the finder switch FS, armature 4 and its'resting contact, upper winding of the line relay 3, wiper 57 of the finder switch FS, armature 48 and its front contact, armature 52 and its front contact, to ground. Line relay 3 of the calling subscribers line energizes over this circuit and completes a locking circuit for itself at armature 6 and its front contact, and at armature 5 and its front contact, grounds conductor by way of wiper 55 of the finder switch FS. At armature 4 and itsresting contact, line relay 3 disconnects its upper winding from across the line conductors 1 and 2, thereby removing the short across the line conductors so that the ringing current now operates the bell at the subscribers station.

The operator restores the ringing key K2 to its normal position after the ringing current has been transmitted over the trunk line for a short interval thereby causing the A. C. relay 14 to restore to normal, which relay in turn opens the circuit for relay 21 and at armature 28 and its resting contact it again prepares the circuit for relay 101. Relay 21 falls back and at armatures 49 and 52 and their respective resting contacts extends the calling subscribers line over conductors 62- and to the upper lower left-hand windings of the repeating coil R. Relay 21 also shunts the holding winding of the subscribers line relay 3 and it restores to normal. In the manual exchange relay 117 operates in series with relay 101 in the O. C. X. over the previously traced circuit including the conductor 116of the trunk line TL. The subscriber removes his receiver after being signalled by the operator and informs the operator at the manual exchange of' the number of the wanted subscriber.

The description of the operation of the circuit when it is necessary for the operator to call a subscriber that has initiated a call is completed. It maybe well to point out, however, that the feature of permitting a subscriber that originatesa call to hang up his receiver, leaving his line relay locked up, has been included because only one connection can beestablished at a time.

Therefore, if the subscriber originates a call whenv change.

the single trunk line is busy, he need not make several attempts to get the operator because his call will be locked in and when the trunk line is available the finder will pick up his line and sig- ,nal the operator who will ring-back over the line to signal the calling subscriber.

The description of the operation of the circuit about to be given is the same whether the subscriber at substation T1 removed his receiver and waited for the operator to respond to his call or if he did not remove his receiver and waited for the operator to signal him.

When the operator at the manual exchange receives the number of the wanted subscriber, for example the subscriber at substation T2, she plugs her dialling cord DC into the dial jack J1 and manipulates the calling device CD in accordance with the number of the wanted subscribers line. As soon as the calling device is moved from its normal position, a circuit is ciosed from ground at the off-normal spring in the calling device CD, tip of the plug in jack J1, winding of relay 124, to battery. Relay 12 1 operates and at normally closed contacts controlled by armature 135 disconnects the impedance 121 from the upper line conductor, and connects battery by way of the impulsing springs of a calling device CD and the sleeve of the plug and jack J1 to the upper line conductor. It should be noted, that relay 16 in the O. C. X. is now energized from battery at the interrupter springs of the calling device CD over conductor 115 of the trunk line TL instead of from battery at the impedance 121 in the manual ex- As the calling device CD is restored to normal, the circuit of relay 16 is interrupted by the opening and closing of the interrupter springs of the calling device CD. Each time relay '16 falls back responsive to the momentary opening of its circuit, a circuit is closed from ground, armature 34. and its resting contact, armature 32 and the front contact, over one path including the winding of the slow-to-release relay 12, to battery, and over another path through the winding of the magnet 9 of the connector switch C6, to battery. The slow-to-release relay 12 will remain energized throughout the series of impulses transmitted to the rotary magnet 9 by the momentary deenergization of the relay 16. Each time relay 16 is energized again responsive to a momentary closure of the interrupter springs of the calling device CD, relay 15 receives another charge of current to maintain it in its energized condition throughout the series of impulses. Each time the circuit of the rotary magnet 9 is opened, the magnet deenergizes and advances the wipers 5861 one step. On the first rotary step of the wipers 586l, the off-normal springs 24 are closed. However, the closure of the oif-normal springs 24 has no effect at this time because the slow-to-release relay 15 is maintained energized. Each time the impulsing relay 16 momentarily falls back and closes the above-mentioned circuit for therotary magnet, the magnet energizes and responsive to the reenergization of the relay 16, the circuit of the magnet 9 is opened, thereby advancing the CD. It should be noted that the ring contact of V the dialling cord DC is grounded in order to maintain relays 120 and 118 energized if the operator should desire to remove her cord circuit CO from the answering jack J After the rotary magnet has been operated by impulses transmitted by the relay 16, the following circuit is completed in series with the rotary magnet: battery, winding of magnet 9, self-interrupting contacts at the end of the rotary magnet 9, off-normal springs 24, (closed on the first rotary step of the wipers 58-61) armature 33 and its front contact, winding of relay 18, to ground. Relay 18 energizes over this circuit but the rotary magnet does not. At armature 39 and its front contact, relay 18 prepares a circuit for relay 17.

When the operator has finished dialling, she operates her ringing key K2 in the same manner previously described, thereby transmitting ringing current over the trunk conductors to operate the A. C. relay 14 in the O. C. X. At armature 28 and its resting contact, A. C. relay 14 opens a point in the circuit of relay 101 and at armature 29 and its front contact, completes an energizing circuit for relay 17.

The opening of the resting contacts of armatures 37 and 38 by relay 1''! has no effect at this time. At armature 35 and its front contact, relay 17 connects the upper line conductor 1".of the called subscribers line to the conductor 63 over which the ringing current is being transmitted, and at armature 36 and its front contact grounds the lower line conductor 2' of the called subscribers line. The ringing current is now transmitted by way of armature 35 and itsv front con tact, wiper 58 of the connector switch CS, conductor 1', armature 4' and its resting contact, upper winding of line relay 3', conductor2, Wiper 61 of the connector switch CS, armature 25v and its resting contact, armature 36 and its front con tact, to ground. Line relay 3 of the called subscribers line energizes over this circuit and it closes a locking circuit for itself at armature 6' and its front contact, and at the same time it removes the upper winding from across the line conductors 1' and 2'. When the upper winding of relay 3 is disconnected from the conductors of the wanted subscribers line, ringing current is projected over conductors 1 and 2' to ring the bell at substation T2.

When the ringing current is transmitted to signal the wanted subscriber, the current flowing in the right-hand winding of. the repeating coil R induces a current flow in the left-hand winding of the coil over the calling subscriber's loop circuit thereby giving the calling subscriber an indication or tone signal indicative of the factthat theoperator. is signalling'the wanted subscriber.

The operator at the manual exchange restoresthe ringing key K2 to its normal position after the subscriber at substation T2 has been signalled. When the ringing is disconnected from the -conductor 116 of the trunk line TL at the front contact of key K2, A. C. relay 14 restores to normal and again prepares the circuit for relay 101 at armature 28 and its resting contact, and at armature 29 and its front contact opens the circuit for'relay 17 which accordingly falls back. .At'

the resting contact controlled byarmatures 35 and 36, relay 17 extends the wanted subscribers line by way of the front contacts of armatures 42 and 48 to the line conductors of the calling subscribers line. At armature 38 and its resting contact, relay 17 closes a circuit by way of the wiper 60.for short-circuiting the lower holding winding of relay 3' thereby causing line relay 3' to restore to its normal position. When the resting contact of the ringing key K2 is closed, relays 117 and 101 energize again over the previously traced circuit.

When the subscriber at substation T2 removes his receiver the conversation between the subscriber at substations T1 and T2 can now take place. The talking circuit is as follows: from station T1, conductor 1, wiper 54 of the finder switch FS, armature 42 and its front contact, armature 35 and its resting contact, wiper 58 of the connector switch CS, conductor 1', of station T2, conductor 2, Wiper 61 of the connector switch CS, armature 25 and its resting contact, armature 36 and its resting contact, armature 48 and its front contact, wiper 57 of the finder switch FS, conductor 2, to the subscriber at substation T1.

The operator at the manual exchange will hold the trunk so that she may supervise the call and release the connection when the subscribers give her the usual disconnect signal when they ringoff.

When the conversation is completed the subscribershang up their receivers and operate their hand generators to transmit ringing current over their lines and line relays 3 and 3' operate. It should-be noted that the holding winding of relay 3 is short-circuited from ground at armature 51 and its resting contact. Therefore, the relay will chatter responsive to the ringing current but the lightly adjusted armature 5 and its front contact remain closed as long as current is on the line. Line relay '3 operates in the same manner as line relay 3 and is short-circuited fromground at armature 26 and its resting contact. At armature 5 and its front contact, relay 3 closes a circuit from ground, armature 5 and its front contact, wiper 55 of the finder switch FS, conductor 65, armature 110 and-its front contact, conductor 66, armature 50 and its resting contact, armature 43 and its front contact, winding of relay 22, to battery. A circuit is also completed by line relay 3' from ground, armature 5 and its front contact, wiper 59 of the connector switch CS, armature 37 and its resting contact, winding-of relay 22, to battery. Relay 22 energizes over either of these circuits and at armature 53 and its resting contact opens the series circuit, over the lower trunk conductor, or relays 101 and 117. The falling back of relay 101 has no efiect at this time. The falling back of relay 117 completes a circuit at armature 125 and its resting contact for giving the manual exchange operator disconnect supervision.

It should be noted that relay 22 maintains the series circuit of relays 101 and 117 open only as long as the subscribers operate their hand generators. Therefore, relay 22 falls back and again completes the circuit for relays 101 and 117 when the subscriber stops turning the hand generator.

When the manual operator receives the disconnect signal, she will remove her dialling cord DC and her calling cord CC from the jacks J1 and J 2, respectively. When ground is removed at contact 139 of the answering jack, relays 118 and 120 restore to normal. Slow-to-release relay 119 falls back responsive to the deenergization of slow-torelease relay 120. Relay 118, however, falls'back immediately and at armature 128 and its front contact opens the circuit for relays 117 and 101. At armature 126 and its front contact, relay 118 opens the series circuit over the upper trunk conductor 115 which includes impedance 121 in the manual exchange and relay l6 in'the O. C. X. Relay l6 deenergizes and opens the circuit of relay 15 which also falls back with slow-action. At armature 30 and its front contact, relay 16 opens the locking circuit of relay 103 and relay 20. Relays 20 and 103 restore to normal. At armatures and 43 and their respective front contacts, relay 25 disconnects the calling and the called subscribers lines. The restoration of relay 103 to its normal position prepares a circuit for relay 102 from the 12-volt O. C. X. battery, winding charging relay 102, armature 114 and its resting contact, the normally closed contact controlled by armatures 109 and 113 of relay 103, over conductors 115 and 116 of trunk line TL, to

armatures

129 and 140. As soon as slow-to-release relay 119 restores to normal the circuit of relay 102 is extended by way of the resting contacts of

arinatures

129 and 140, armature 136 and its resting contact, winding of the charging relay 122 in the manual exchange, normally closed contacts of key Kl, charge-control rheostat CCR to the 24-volt manual exchange battery. Relays 102 and 122 operate over this circuit. The operation of relays 102 and 122 will be described more in detail hereinafter. At armature 1'34 and its resting contact, relay 122 opens a point in the circuit of relay 123. v

Referring again to the release of relay 16 in the O. C. X. At armature 34 and its resting contact, relay 16 completes an energizing circuit for the rotary magnet 9, and slow-to-release relay 12. When the sloW-to-release relay 15 falls back it opens the circuit, for thejmagnet thereby causing it to release and advance its wipers to the next step; Relay 12 remains energized for a short interval due to its slow action and at armature 26 and its resting contact removes ground from wiper'60 so that any line relays that are locked up will not be shunted down as the connector restores its wipers to normal. At armature 33 and its resting contact, relay l5 completes a selfinterrupting circuit for the rotary magnet 9 by way of the ofI-normal contacts 24 and the selfinterruptingcontacts 10 of the rotary magnet 9. The rotary magnet continues to operate and interrupt its own circuit until the wipers of the switch are restored to their normal position, at which position the off-normal springs 24 are opened thereby bringing the wipers of the switch to rest. The equipment in the O. C. X. is now restored to normal and will respond to extend a connection to the operator at the manual exchange when the subscriber initiates a call.

Charging of the battery at the operator controlled exchange I It will be noted that there are several battery symbols in the O. C. X. each indicating a battery with a positive pole grounded and the negative pole free. It should be understood, however, that these symbols represent the same battery. It will also be noted that several battery symbols shown in the manual exchange, each indicating a battery with the positive pole grounded and the negative pole free. Each of these symbols r present the battery in the manual exchange. The manual exchange battery has a voltage of approximately twenty-four volts and is the regular exchange battery, whereas the battery in the O. C. X. is approximately twelve volts. When the equipment in the O. C. X. is not in use, current is normally flowing from the battery in the manual exchange by way of the charged control rheostat CCR, normally closed contact of key K1, winding of relay 122, and armature 133 and resistance 130 in parallel with the winding of relay 122, armature 136 and its resting contact, the two conductors 115 and 116 of the trunk line TL, resting contacts of

armatures

129 and 140, respectively, upper and lower left-hand windings of the repeating coil R1, normally closed contacts controlled by armatures 109 and 113, armature 114 and its resting contact, over one path including the winding of relay 102 to battery in parallel with the circuit including armature 107 and its front contact and resistance 141 to battery. It should be noted that relays 102 and 122 are maintained energized over this circuit and that the

resistances

140 and 1 11 are shunted around the windings of relays 122 and 102, respectively, toprevent the relays from becoming overheated due to the continuous current flow over the circuit. It is evident from the foregoing that the battery in the O. C. X. is floated over the trunk line by the manual exchange battery. Key K1 is provided for disconnecting the charging circuit from the manual exchange battery to the O. C. X. battery and for connecting ground to relay 122 for the purpose. of maintaining the relays 122 and 102 energized so that the manual exchange operator can be signalled when an O. C. X. subscriber desires to make a call.

Call from manual exchange subscriber to O. C. X. subscriber If a subscriber in the manual exchange desires to converse with the subscriber in the O. C. X. the operator at the manual exchange will extend the connection by plugging in her cord circuit into the jack J. Relays 118 and 120 are energized from contacts 139 of the jack J. Relay 119 operates responsive to the operation of relay 120 and at the resting contacts of

armatures

129 and 140 disconnects the charging circuit causing the release of relay 122 in the manual exchange and relay 102 in the O. C. X. At the front contacts of these armatures, battery is connected to the upper line conductor from impedance 121 and battery is connected to the lower line conductor by way of relay 117. In the O. C. X. relay 102 upon falling back, causes the energization of relay 103 of armature 106 and its resting contact. At armatures 109 and its front contact, relay 103 extends battery from the impedance 121 over the conductor 115 of the trunk line TL, armature 109 and its front contact, conductor '72, winding of relay 16 to ground. At armature 113 and its front contact, relay 103 extends battery from relay 117 over the lower trunk' conductor 116, armature 113 and its front contact, conductor '70, armature 20 and its resting contact, armature 53 and its resting contact, conductor 71, winding of relay 101 to ground. Relay 16 in the O. C. X. energizes and relay 101 in the O. C. X. energizes in series with relay 117 in the manual exchange. Relay l5roperates responsive to the operation 'of relay 16 and prepares the connector switch CF in the O. C. X. for operation.

The operator in the manual exchange may now position the connector switch CS to the wanted subscribers line, which in this case is assumed to be the line of the subscriber at substation T2. The operation of the circuit is the same as has been described hereinbeicre. Therefore, it Will suffice to say that the operator dials over the trunk and positions the connector CS to the line of substation T2 and operates her key K2 to signal the subscriber at substation T2. When the subscriber removes his receiver the subscriber at the manual exchange and the subscriber at substation T2 can converse. When the conversation is completed the subscribers hang up their receivers and the subscriber at substation T2 rings off in the same manner described hereinbefore to give the manual exchange operator disconnect supervision.

The operator at the manual exchange removes her cord circuit CC, and relays 118 and 120 in the trunk circuit fall back. At armature 126 and its front contact, relay 118 removes battery from the upper trunk conductor 115, thereby causing the release of relay 16 in the O. C. X. exchange. Relay 15 also falls back and at armature 33 and its resting contact completes a circuit for the magnet 9 which interrupts its own circuit, thereby advancing the wipers 5851 to their normal home position at which position, off-normal contacts 24 are opened to stop the rotary action of the magnet 9.

Relay 103 in the O. C. X. is released responsive to the deenergization of relay 15. At the normally closed contacts controlled by the front contacts of armatures 109 and 113, relay 103 again connects up the charging circuit in the O. C. X. and at the resting contacts of

armatures

129 and 140, relay 119 connects up the charging circuit in the manual exchange. Relay 192 and relay 122 energize as before to complete the charging circuit.

What is claimed is:

1. In a combined manual and operator controlled telephone system, a trunk line extending from the manual exchange to the operator controlled exchange, a finder switch and a connector switch in the operator controlled exchange permanently connected with said trunk, means controlled over a calling line for operating said finder to connect the trunk line with the calling line, an impulsing relay in the operator controlled exchange controlled over one conductor of said trunk line from the manual exchange to set the connector switch on the contacts of a desired called line to complete a desired connection.

2. In a telephone system, an automatic connector switch having normally connected wipers, means under control of a calling party for transmitting impulses to said switch to advance the Wipers into engagement with contacts of the desired line, an alternating current relay in said switch, said relay operated responsive to the application of ringing current to said connector, and means controlled by said relay for connecting a branch circuit over which the ringing Eu? rent is transmitted to signal the subscriber on said line.

3. In a telephone system, a finder switch accessible to a plurality of lines and arranged to stand normally in any arbitrary position, aconnector switch having access to the same plurality of lines, an operators position, means responsive to the initiation of a call by a subscriber on one of said lines for operating said finder to find said line and for signalling the operator, means controlled by the operator for operating the connector switch to select the wanted subscribers line and for signalling the wanted subscriber on the line, means controlled by the subscribers after they hang up their receivers for giving the operator disconnect supervision, and means controlled by the operator for causing said connector to restore to normal.

4. In a telephone system, a calling line, a finder switch adapted to find said line, a trunk line extending to an operators position, means responsive to the initiation of said call for operating said finder to find said line, means responsive when said line is found for connecting the line to said trunk line, means responsive to the connection of said trunk line with said subscribers line for signalling the operator, means controlled by the operator for transmitting ringing current over said trunk line, a relay responsive to said ringing current, and means controlled by said relay for transmitting said ringing current over said calling line to signal the subscriber connected thereto.

5. In a telephone system as claimed in claim 4, in which the calling line may be further connected with a called line, and in which the relay initially operated to control the application of ringing current to the calling line is subsequently operated to control the application of ringing current to the called line.

6. In a telephone system, a trunk line extending from a manual exchange to a second exchange, a storage battery in the second exchange, circuit connections for charging said battery over said trunk line from a storage battery in said manual exchange, and a charge control rheostat included in said circuit for regulating the current flow from the manual exchange battery to said second exchange battery.

"7. In a telephone system, a trunk line extending from a manual exchange to a second exchange adapted to be used for talking purposes, a storage battery in said second exchange, circuit connections for charging said battery over said trunk line from a storage battery in said manual exchange, a charge control rheostat included in said circuit for regulating the current flow from the manual exchange battery to said second exchange battery, means included in said circuit operated responsive to the seizure of said trunk line by a subscriber in said second exchange for disconnecting the charging circuit, and means in said manual exchange operated responsive thereto for signalling the operator at the manual exchange.

8. In a telephone system, a subscribers line, a line relay for said line adapted to be operated over a circuit including an operating Winding bridged across the line when the subscriber initiates a call, to lock itself over a locking winding and to disconnect the operating winding from across the line, a finder switch for extending said subscribers line to an operators position, con-- Eacts on said relay for marking the subscribers line in the bank of said finder and for completing a circuit for operating the finder to find the marked line, and means operated when the marked line is found for shunting the locking winding of said relay thereby releasing the relay and again connecting the operating winding across the line.

9. In a telephone system, a subscribers line, a line relay for said line adapted to be operated over a circuit including an operating winding bridged across the line when the subscriber initiates a call, to lock itself .over a locking winding and to disconnect the operating winding from across said subscribers line, a trunk line, a switch operative for extending said subscribers line to said trunk line, means controlled by the ener gization of said relay for operating said switch to connect the subscribers line to said trunk line, and means operated in response to said connection for deenergizing said relay to again connect the operating winding of said relay across the subscribers line.

10. In a telephone system, a subscribers line, a trunk line, a line relay individual to the subscribers line, means controlled by the subscriber in initiating a call for energizing said relay, 2. locking circuit for maintaining said relay energized after the subscriber replaces his receiver in case the trunk line is busy, a switch operated in response to the trunk line becoming idle for connecting the subscribers line to said trunk line, and means responsive to said connection for deenergizing said relay.

11. In a telephone system, a subscribers line, a trunk line, a line relay individual to the subscribers line, means controlled by the subscriber in initiating a call for energizing said relay, a locking circuit for maintaining said relay energized after the subscriber replaces his receiver in case the trunk line is busy, a switch operated in response to the trunk line becoming idle for connecting the subscribers line to said trunk line, means responsive to said connection for deenergizing said relay, and means for signalling the subscriber to inform him that-his call may be further extended.

12. In a telephone system, a calling line, a called line, a finder-connector link circuit for connecting said lines, an alternating current relay in said link circuit, said relay operated iresponsive to the application of ringing current to said link circuit, means controlled by said relay for connecting a branch circuit over which the ringing current is transmitted over the called line to signal the called subscriber, and meansin said link circuit for transmitting an induced ring-back tone in the calling line in response to the application of said ringing current to the link circuit.

13. In a telephone system, a subscribers line, a line relay having an operating winding and a locking winding, said relay energized over its operating winding and locked energized over its locking winding in response to the subscriber initiating a call, an automatic switch, a circuit closed in response to the connection of said switch to said line to shunt said locking winding to deenergize said relay, said relay energized over its operating winding and locked energized over its locking winding in response to the application of ringing current to said line when it is a called line, and another circuit closed to shunt said locking winding to deenergize said relay when ringing current is disconnected from said line.

14. In a telephone system, subscribers lines, a line relay individual to each subscribers line, each of said relays energized and locked energized in response to the subscribers on such lines initiating a call, a connector switch having access to said lines, wipers on said connector switch operated from normal position over said lines to connect with a called one of said lines, a normally closed circuit in said connector switch including one of said wipers, means for releasing said connector switch after operation by operating the wipers over said lines to normal position, and a relay operated during the restoring operation of the connector switch to open said normally closed circuit to prevent the deenergization of any of the relays which were locked energized in initiating a call.

15. In a telephone system, a calling line, a called line, a finder-connector link for connecting said lines, means responsive to the calling party initiating a call for operating said finder of the link to connect the calling line to said link, means for directively operating the'connector of the link to connect with the called line, an alternating current relay in said link oper ated in response to the application of ringing current to said link circuit, means operated in response to the operation of said relay in case only the finder has been operated for connecting said ringing current to the calling line, and means operated in response to the operation of said relay in case the connector has been operated for connecting said ringing current to the called line.

16. In a telephone system, a first exchange, subscribers lines in said exchange, a second exchange, a trunk line comprising only two conductors connecting said exchanges, a connector switch in said first exchange having access to said subscribers lines, said connector switch operated over said trunk line from the second exchange to connect a calling subscriber in the first exchange connected to said trunk line to a called subscriber in the same exchange, a relay in said switch operated in response to either subscriber transmitting a disconnect signal, contacts operated by said relay opening one of the conductors of said trunk line, a relay in the second exchange operated responsive to the opening of said one conductor, and supervisory means at the second exchange operated by said last relay.

1'7. In a telephone system, a calling line, a called line, a finder-connector link operative for connecting said lines, an alternating current relay in said link operated in response to the application of ringing current to said link circuit, and means operated by said relay for connecting said ringing current to either the calling or the called line dependent upon whether the connector of said link is operated at the time of the application of said ringing current.

18. In a telephone system, a calling line, a called line, a finder-connector link for connecting said lines, said finder operated in response to the initiation of a call on said calling line to find and connect with such calling line, a trunk line terminating said link, said connector operated over said trunk line to connect with said called line, and a single ringing key connecting ringing current to said trunk line when operated to ring either the calling subscriber or the called subscriber dependent upon whether the connector is operated at the time of the connection of ringing current to said trunk line.

19. In a telephone system, a first and a second exchange, a trunk line connecting said exchanges, a storage battery in the first exchange, circuit connections for charging said battery over said trunk line from a source of current in the second exchange when the trunk line is idle, a relay at each end of said trunk line normally energized by said charging current, means responsive to the seizure of said trunk line at the second exchange for opening said circuit connections to deener'gize said normally energized relays, a second relay in the first exchange operated to open a further point in said circuit connections and to condition said trunk line for use in establishing a telephone connection in response to the deenergization of the relay in the first exchange, and a delay device operated a predetermined time after the seizure of said trunk line in response to said seizure to further condition said trunk line for telephonic use.

20. In a telephone system, a first and a second exchange, a trunk line comprising only two conductors connecting said exchanges, and circuit combinations arranged to transmit charging current over the two conductors in parallel when the trunk line is idle, to transmit impulses over only one of said conductors when extending a telephone connection, to transmit ringing current over the other of said conductors for signalling purposes, and to supervise an established connection over the said other conductor.

EDl/VARD S. PETERSON.