US1604597A - Composite ringer circuit - Google Patents

Description

- Oct. 26 1926. 1,604,597

H. W. ONEILL COMPOSITE RINGER CIRCUIT Filed Oct. 22. 1924 2 Sheets-Sheet 1 Oct. 26, 1926,. 1,604,597

H. W. O NElLL COMPOSITE RINGER cnzcum Filed Oct. 22. 1924 2 Shets-She'at 2 Fatentecl Get. 26, 1926.

time STATES PJ'ENT HENRY W. ONEILL, OF ELMHTJ'RST, NEW' YORK, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, 1?. f, A CORPORATION OF NEW YORK.

COMPOSITE RINGER CIRCUIT.

Application filed October 22, 1924. Serial No. 745,089.

This invention relates to composite ringer sets for relaying low frequency currents into currents of high frequency and vice versa.

Composite ringer sets are quite generally interposed between a line and a switchboard on composited, repeatered and other similar line circuits, and serve to prevent low frequency signaling or ringing currents from reaching telegraph apparatus on composited circuits, and also to apply current at higher frequencies to telephone circuits in order that the current may traverse the telephone circuits without excessive attenuation. A standard type of composite ringer set now in general use, is adapted to relay the usual switchboard ringing current of 16 or 20 cycles per second, to current at 135 gycles per second at the opposite or line side of the set, while inversely 135 cycle current incoming at the line side of the set is relayed to 16 or 20 cycle current at the switchboard side of the set.

Heretofore, it has been the practice to employ sources of alternating current which comprise equipment or units separate and d iinct from the composite ringer sets themselves. For example, for ringing in one direction, the applicationof current from a 16 or 20 cycle source effects the response of relays to switch the line circuit from the switchboard circuit to a source of 135 cycle current, while for signaling in the opposite direction, current from a 135 cycle source effects the response of other relays to switch the switchboard'leads from the line to a source of 16 or 20 cycle current.

\Vith the composite sets, as hereinbefore described, dependent upon separate source of ringing current at the sets, it has not been possible to employ composite ringers except where such separate sources of current are available. Thus the use of such sets has been limited to such points where the traffic load is heavy enough to warrant the installation of ringing generators. In accordance with the present invention, it is proposed to dispense with the separate sources of current and to provide that the receiving relays may at proper times also serve as vibrators to effect the generation of alternating current at corresponding frequencies for carrying out the necessary signaling operations. The composite set is thus rendered complete within itself and enables the use of the set at any isolated point or at points where, due to lower traffic loads during the night, Sundays or at other times, it becomes inadvisable to'maintain the power equipment in continuous operation.

It is the object of the present invention justod, and have large energy output, as

distinguished from vibrators of the interrupter type which have heretofore been proposed. The vibrator relay is arranged in the composite set in such a manner that it operates eiiiciently at certain times as a current responsive device and at other times as current generating device.

It is believed that the invention will best be understood from a consideration of the drawings and the following detailed description thereof Fig. 1 shows a composite ringer set in which a transformer is employed for connecting the vibrator relay with an outgoing line, the transformer being common to a plurality of ringer sets.

Fig. 2 shows a composite ringer set employing an alternating current vibrator relay which is inductively coupled to the outgoing line both when the relay is serving as a generating and as a responsive device.

Fig. 3 taken in connection with the portion of Fig. 2 to the left of the dot and dash lineshows a modification of the set shown in Fig. 2, condensers being used as an inductive coupling between the vibrator relay and the outgoing line.

Fig. 4E shows a further modification in which a retardation coil serves as a coupling between the vibrator relay and the outgoing line and also as retardation in the 20 cycle and 135 cycle bridges of the set.

- Fig. 5 shows a composite set arranged to receive 135 cycle current from the outgoing line and repeat 20 cycle current to the switchboard line and to receive 20 cycle cur rent from the switchboard line and repeat 135 cycle current'to the outgoing line, vi-

brator relays serving as generating devices for both frequencies of current.

Fig. 6 shows a composite set arranged with a high pass filter for conveying voice currents around the relays of the set.

Throughout the several figures of the drawing, the same numerals have been applied asfar as possible to simil r pieces of apparatus disclosed cinthe several figures.

Referring particularly to Fig. 1, a line circuit is shown at 1-2, outgoing "from the composite set and a switchboard line 3t extending from the set to a switchboard of an exchgimge system. Inasmuch as the invention not concerned withthe particular structure and operation of the outgoing line, and switchboard, they .havenot beenriis, closed herein, A source of 20 cycle current is shown at 5 and a vibrator relay at 6 which is capable of responding to 135 cycle current incoming over the line 1-2' and of generatingcurrent at 135 cycles for transmission over line 1-2. A transformer 11 common to a plurality of composite sets is provided for controlling the relays 6 of such sets in converting direct current into alternating current at the desired frequency.

In the operation, of, the composite set shown in Fig. 1, low frequency signaling current of," for example, 20 cycles applied. to the switchboard line 8i, flows over conductor 3, the upper back contact ofswitching relay 7, through the retardation coil 12, condenser 13, alternating current relay 9, which is adjusted to respond to signaling current of 20 cycles, lower back contact of relay 7 to the conductor 4. Relay 9 responds, closing a circuit from battery through the winding of switching relay 8, winding of relay 14, contact of relay 9 to ground at the back contact of relay 10. The energization of relay 8 disconnects the outgoing line 12 from the talking conductors of the set and. con: nects the line 12 to the right winding of common transformer 11. Relay 1 1 opens the circuit extending through relay 1O to prevent its operation at this time and establishes a circuit for the vibrator'relay 6, which extends from battery through the left windings of the transformer 11, the intermediate front contact of relay 14;, both windings of relay 6 in series, to ground at the upperffront contactof relay 14:. Relay fijener'giz es in thiscircuit and at its contact'scloses a shunt about its own windings, extending from ground at the contacts of relay 6 through the lowerand intermediate front contacts of relay 14, both windings of relays 6 togrdund at the upper front contact of relay ll. As soon asthis shuntiis ,e'lfective relay 6 de energizes, Thus, relay 6 co inues'to ener- Ugize and deenergize in avib'ratoryjmanner so long as relay 14rennains operated. The

current changes thus set up in the left windings of transformer 11, are induced into the right winding of the transformer and transmitted to the line 1-2. A condenser 15 connected in shunt to a portion of the windings of relay 6 through the intermediate front contact of relay 1th, serves to adjust the speed at which the tuned reed armature of relay 6 may tend to operate, while the relay is serving as a vibrator, the value of condenser 15 being such as will bring the frequency of operation of thearmature of relay 6 to 135 cycles.

To protect the contacts of relay 6 against the possibility of sparking, a resistance 17 and condenser 16 are connected to ground in parallel with the ground connection through the relay contacts, through the lower front contact of relay 14-. A condenser 19 in series with resistance 18 is bridged around the right winding of transformer 11 as an arti ficial load for steadying and insuring uniformity of operation of the vibrator relay 6 of any composite set, irrespective of whether one or several sets may be connected at one and the same time to receive signaling current from the common transformer 11.

Since, as the multiple connections indicate, all vibrator relays 6 receive current in parallel through the left windings of common transformer 11 and through contacts of associated relays 14, it follows that whenever one of the relays 6 is operated as a vibrator and its windings are thus short circuited through its contacts at that instant, no other relay 6 may receive current. It therefore follows, that the relays 6 may receive energy only during such instants as all vibrators may be restored or with their respective contacts open, and all relays will be 'short circuitedduring the periods that the contacts of any relay may remain closed. As a consequence, the resulting 135 cycle current produced in and supplied by the transformer 11 will be of even phase irrespective of whether one or more vibrator relays may be in action at the same time.

When a signaling current of 135 cycles is incoming to the composite set, this current flows over conductor 1, the upper back con tact of relay 8, retardation coil 12, condenser 20, upper back contact of relay l t, windings of relay 6, middle lower back contact of relay 14, lower back contact of relay 8 to conductor 2. The response of relay 6 to this current, intermittently closes the circuit extending through the contacts of relay 6 and the lower back contact of relay lithrough the winding of relay 10, causing the operation of relay 10 and the consequent operation of relay 7. Relay 10 in operatingalso' removes ground from the operating circuit of relay 14 to insure that the latter relay may not be capable of operration at this time. Relay 7 upon operating, opens the normal connection of the switchboard line 34; to the talking conductors of the set, and connects the line to the 20 cycle source 5 of signaling current for operating any suitable signal at the switchboard. A; condenser 21 is placed in bridge of all or a major portion of the winding of relay for the purpose of enabling relay 10 to maintain its armature attracted during the half cycle periods during which the contacts of relay 6 are open, so that the application of current from the source 5 to the line S iis maintained steady during the entire period when 135 cycle current is being applied over the line 1 2 to the relay 6. As soon as signaling is completed in either direction, and relays 7 and 8 are both in an unoperated condition, a talking circuit is established between the line 12 and the line 3-4 over the back contacts of these relays and the heavy conductors.

The modification shown in Fig. 2 is similar to that shown in Fig. 1 with the exception that the vibrator relay 6 is induc tively connected to the line 12 through a transformer 22 which is individual to the composite set, the relay being inductively connected to the line 1-2, both when it is functioning as a vibrator for generating current and as a responsive device. On outgoing signals, relay 9 functions in the manner previously described in connection with Fig. l and closes the circuit of switching relay 8. Switching relay 8 upon energizing disconnects the limbs of line 12 from the talking conductors extending through the composite set, opens the circuit extending to the relay 10 to prevent this relay from falsely functioning at this time and prepares a shunt path around the windings of relay 6. Relay 9 also closes an operating circuit for the vibrator relay 6, extending from battery through the left winding of transforn'ier 22, both windings of relay 6 to ground at the upper contact of relay 9. Filth relays 8 and 9 operated, as soon as relay 6 energizes, it shunts its own windings by a circuit extending from ground at its own contacts, through. the lower front contact of relay 8, the windings of relay 6 to ground at the upper contact of relay 1. Relay 6 therefore functions as a vibrator relay so long as relay 9 remains enc 5 ed, the surges of current set up in the hi winding of transformer 22, being in plied to conductors 1-2 flows through condenser 2S and the right winding of transformer 22 and inductively operates relay 6, the induced current flowing from the left winding of transformer 22, through both windings of relay 6 and through condenser 20. Relay 6 in response to the 185-cycle current, establishes a circuit for relay 10 8X- tending from batterythrough the winding of relay 10, the lower back contact of relay 6' to ground at the contact of relay 6. Relay 1O responds to this current being held operated during half cycles when the contacts of relay 6 are opened, by discharges from the cond-nser. 16, and establishes an obvious shunt-around the winding of relay i. Relay 2st thereupon deenergizes closing the circuit of relay 7 which in turn disconnects the switchboard line 34 from the talking conductors of the composite set, and connects this line to the -20-cyele generator As indicated by the conventional markings, the relay 7 is both slow to release and slow to operate, and relay 8 is slow to re lease. Such characteristics are to insure against false signals which might result from current surges in combined telephone and telegraph working, and also to insure that premalurerelease of the relays, such as relay 8, may not take place under fluctuations of signaling current during the trans mission of a signal.

Fig. 3 when considered in connection with that portion of Fig. 2 to the left of the dot and dash line illustrates a modification of the invention in which the vibrator relay 6 is inductively coupled to the outgoing line 1 .2 through condensers, both when it is functioning as a generating device and as a responsive device. In response to outgoing signaling current of 20-cycles frequency from the switchboard line 34, relay 9 operates, this relay at this time being bridged across the talking conductors of the set through the condenser 13 and one winding of the retardation coil 25. Relay 9 in operating closes an obvious circuit forrelay 6, which in turn, disconnects the line 1-2 from the talking conductors of the set, opens the circuit extending through'the winding of relay 10 to prevent its operation at this time, and closes the circuit of the vibrator relay 6. The circuit for relay 6 may now be traced from battery, resistance 28, lowermost front contact of relay 8, both windings of relay 6, uppermost contact of relay'8, resistance 29 to ground. Relay 6 upon energizing shortcircuits its windings over a circuit extending from its contacts over the two lower front contacts of relay 8, both windings of relay 6, the upper contact of relay 8, back to Surges in the energizing circuit of relay 6 are then transmitted to the line 12, through the condensers 26 and 27, respectively, which join the opposite terminals of relay 6 with conductors 1 and 2 through front contacts of relay 8. Each time the contacts of relay 6 separate, potential from the battery by way of resistance 28 and condenser 27 passes to the conductor 2, returning over conductorl, through condenser 26 to ground through resistance 29. When the contacts of relay 6 close, the condensers 26 and 27 discharge in series with the loop over conductors l and 2. The fact that the condensers 26 and 27 charge and discharge in series with the line loop insures that the energy in each conductor of the loop will be substantially the same notwithstanding commercial differences in the values of the condensers or the resistances of units 28 and 29 and further, the employment of two resistances 28 and 29 insures substantial symmetry relative to inductive effects on parallel circuits which may be present from any extraneous sources on the two line conductors Relay 8 during its energizat-ion places a shunt circuit around the upper winding of the retardation coil 25, extending over the inner upper front contact of relay 8, which serves to prevent 135-cycle current from being induced through this coil into the low frequency circuits of the set. This also tends to reduce the impedance of the lower winding of the retardation coil, thereby insuring a maximum of ringing current for steadily retaining the relay 9 operated dur ing the ringing interval.

l/Vhen a signal is incoming over the line 12 relay 6 is energized by the incoming 135-cycle current over a path extending from conductor 1, the upper winding of coil 25, condenser 26, windings of relay 6, the lowermost and innermost lower back contacts of relay 8, thence over line 2. Relay 6 closes a circuit for relay 10 extending from battery, winding of relay 10, resistance 30, middle upper back contact of relay 8, contacts of relay 6, resistance 29 to ground. Relay 10 operates in turn causing the operation of relay 7 to apply low frequency signaling current from the source to the switchboard line 3 l. To insure that relay 1-0 will be maintained energized during the half cycle periods during which the contacts of relay 6 are opened, a condenser 31 is placed in shunt of the winding of relay and resistance 30. During the reception of 135-cycle signaling current, the condenser 26 in series with the windings of relay 6 forms a negative reactance which in combination with the impedance of the upper winding of coil establishes a condition of resonancefor the 135-cycle bridge path of relay 6, while the condenser 2'1 in bridge of the windings of relay 6 serves to effect a condition of inverse resonance at this frequency for relay 6.

In the modification of Fig. 4: a single double-wound retardation coil is employed in both the low and high frequency bridges of the set and as a transformer coupling be tween the vibrator relay 6, when it is serv ing as a generating device, and the line 12. For an outgoing signal low frequency current applied to conductors 3-4 at the switch board passes from line conductor a, through relay 9, the upper normal contacts of relay 33, the right winding of retardation coil 35, the intermediate back contact of relay 8, back to conductor 3. Relay 9 responding, closes a circuit extending in parallel through the windings of relays 8 and 33. Relay 3 upon energizing disconnects the limbs of line 12 from the talking conductors of the set and prepares circuits for; coupling relay 6 to the line 12. Relay switches relay 9 to an alternative bridge circuit extending through the upper alternate contact of relay 33 and resistance 34, opens the circuit extending from the winding of relay 10 to prevent its operation at this time, and closes an operating circuit for relay 6 which may be traced from battery, upper front contact of relay 8, left winding of coil 35, windings of relay 6, innermost lower front contact of relay 33 to ground. Relay 6, upon energizing, closes a shunt about its own windings extending from its contacts, middle lower front contact of relay 33, windings of relay 6 to ground at the innermost lower front contact of relay 33. Relay 6 thus operates in a vibratory manner causing surges of current in the left winding of coil 35 which induce current into the right winding of coil 35. The right winding of coil 35 is at this time connected to line 1-2 from conductor 1, through the right winding of coil 35, over the lower front contact of relay 8 to conductor 2. Current of 135-cycles frequency is thus transmitted to the line 12, so long as relay 9 remains energized.

At its lowermost front contact relay 33 connects the condenser 37 in parallel with V the left winding of coil 35 and the condenser 38 is retained in shunt of one winding of relay 6 to maintain the relay 6 vibratory at the proper frequency during its operation as a generator of high frequency current. Relay 8 also through its lower front contact bridges the condenser 36 around the right winding of-coil 35 as an artificial load and sur e path.

In response to signalsof 135-cycle frequency incoming over line conductor 1, condenser 36, upper normal contact of relay 8,

left winding of coil 35, windings of relay 6, innermost lower normal contact of relay 33, lea er ack ontact .i 1 C ductor 2, relay 6 operates. Condenser 36 at this time serves to effect series resonance of relay 6, while the condenser 37 whichis in bridge of the upper winding of relay 6, through the lower back contact of relay 33 and the condenser 38 in shunt of the lower winding of relay 6 serves to efiect parallel resonance with respect to relay 6, thus insuring that relay 6 will properly respond to the frequency of the incoming signaling current.

The operation of relay 6, with relay 33 deenergized, establishes a circuit for relay 10 from battery, winding of relay 10, resistances 30 and 32, middle lower back contact of relay 33 to ground at the contacts of relay 6. Relay 10 operates being maintained operated during the half cycles in which the contacts of relay 6 are open by means of the condenser 31 in shunt of its winding. The operation of relay 10 causes the release of relay 24: and the operation of relay 7 to apply low frequency signaling current from the source 5 to the switchboard line 3-4: as previously described.

In Fig. 5 the invention has been further expanded to show a composite set entirely free from external sources of signaling current, two differently tuned vibratory relays being used as generators of, and devices responsive to high and low frequency current, respectively. It will be first assumed that ringing current of QO-cycles frequency is applied to the switchboard line 34 and that 135-cyole ringing current is to be impressed on the line 1-2. The .QO-cycle current en-' tering the composite set by way of conductor 3 flows over the inner upper back contact of relay 7, retardation coil 39, condenser 41, up permost back contact of relay 7, windings of relay 40, middle lower back contact of relay 7, back over conductor 4:. At this time condenser 4:2 is connected in parallel with the windings of relay 4.0 over the middle upper back contact of relay 7 for the purpose of establishing a condition of parallel resonance for relay 40 at its control frequency of QO-cycles per second. Reciprocation of the armature of relay 4:0 in phase with the 20- cycle current, results in the closure of a circuit for relay 8 extending from battery through the winding of this relay, resistance 43, lowermost back contact of relay 7 to ground at the contacts of relay d0. To insure that the relay 8 will be maintained steadily energized during the operation of relay e0, the condenser 44 is connected from the circuit of relay 8 to ground.

Relay 8 upon energizing opens the normal connection of the limbs of line 1-2 with the talking conductors of the set, opens thecircuit extending through relay 7 to prevent its operation at this time, and prepares circuits for operating relay 6 as a generating device and for connecting it to the line 12. The

energizing circuit of relay 6 may now be traced from battery, through the right winding of transformer 45, the uppermost front contact of relay 8, windings of relay 6 to ground at the middle lower frontcontact of relay 8. Relay 6 energizes and closes a shunt about its windings, extending from ground at its contacts, the lowermost front contact of relay 8, the uppermost front contact of relay 8, windings of relay 6 to ground at the middle lowerfront contact of relay 8. Relay 6 thus operates in a vibratory manner, setting up surges of current in the right winding of transformer 45 which are induced in the left winding of the transformer and transmitted to the line 1-2, over a circuit extending from conductor 1, innermost upper front contact of relay 8, left winding of transformer 45, innermost lower front contact of relay 8, to conductor 2. At its middle upper front contact relay 8 connects the condenser a8 and resistance 46 in shunt of the lower winding of relay 6 to insure that relay 6 when functioning as a generating device shall generate current of the desired frequency.

If desired a condenser 49 may be bridged about the major portion of the right winding of transformer 45 for preventing inductive discharges from this winding from reaching the contacts of relays 6 and .40 at the time they are operating as vibrators. The small portion of the transformer winding not encompassed by the condenser, serves to diminish the instantaneous value of the condenser charging current at such instants as the contacts of relays 6 or 40 are closed to ground. This protects the contacts of the relays from excessive currents which may be present when the circuits are designed for heavy current output. This condenser 49 also serves for increasing the output of alternating current and may serve for phase correction in situations where the electrical and mechanical time constants of the circuits and vibrator relays may not be definitely proportioned to the frequency employed. This more particularly concerns conditions of symmetry relative to the duration of the open and closed 1 periods of the cont-acts of the vibratory relays. lVhen properly designed and proportioned electrically and mechanically, however, the closed and opened periods of the vibratory relays may be in such agreement as to result in symmetry with respect to suecessive half waves of the alternating current produced Without recourse to a condenser as a correcting means.

For signals in the opposite direction with relay 8 deenergized, relay 6 functions as a responsive device being bridged similarly to relay 40 across the line 1-2 through the retardation coil 50 and condenser 47, and is operative in response to 135-cycle current been shown applied to a standard composite set in which the switchboard line is normally connected with the outgoing line through a high pass filter. hen low frequency signaling current of 20 cycles is applied atthe switchboard to the line 3 l, this current traverses the upper back contact of relay '7, upper winding of retardation coil 53, condenser 54, relay 9, lower wind ing of coil 53 and the lower back contact of relay '7 causing the operation of relay 9. Relay 9 upon operating closes obvious circuits for relays 55and 56, therelay 56 dis associating the high pass filter 57 from the line 3-l. Relay 55 disconnects the wind ing of relay 10 from the contacts of relay 6 to prevent its operation at this time, connects the relay 6 to the line 1.-2, through the transformer coil 58, and establishes an energizing circuit for'relay 6. This energizing circuit may be traced from battery, innermost lower contact of relay 55, upper winding of coil 58, windings of relay 6 to ground at the lowermost front contact of relay 55. Relay 6 energizing in this circuit, closes a shunt about its windings from ground at its contacts, through the middle lower front contact of relayr55, windings of relay 6 to ground at the lowermost contact:

of relay 55. Relay 6 thus operates in a vibratory manner setting up sergesxof current in the upper winding of coil 58 winch are 111- duced in the lower winding of this coil and.

incoming over line 1-2, with relay 55 deenergized, this current flows from conductor 1 through the lower winding of coil 58, condensers 60, lower back contact of relay 55, windings of relay 6, upper winding of v coil 58, upper back'contact of relay 55 to conductor 2. Relay 6 in responding to this current closes the circuit of relay lOxextending from battery through relay 10, resistances'30 and 32, middle lower baclr contact ofrelay'55 to ground at the: contacts of tained energized during half cycle periods Condensers 59 in bridge.

when the contacts of relay 6 are opened, by the discharge of condenser 31. Relay 10, in operating, shunts the winding of relay 2%, which upon 'deenergizing, closes the circuits of relays 61 and 7 in parallel. Relay 61 closes an obvious circuit for relay 56 which disconnectsthe high pass filter 57, and relay disconnects the relay 9 from the line 3t and connects the 20-cycle source of ringing current 5 thereto. The condensers includedin the bridge circuit of relay 6 serially resonate the circuit of relay 6 so that this relay responds properly to signaling current of-l35 cycles. It is to be noted that the retardation coil 58 serves a double purpose, first, to reduce transmission losses during conversation, and secondly, during the transmission of 135-cycle current, as a transformer for connecting the vibrator relay 6 with the outgoing line 1 -2.

IVhile the vibratory relay in accordance with applicants invention has been shown as embodied in several difi'erent types of composite sets, it is obvious that a relay of this general type might, be employed in circuits of other types for generating or responding to an alternating current at any desired frequency within the mechanical limitations of the relay structure.

VVhatis claimed is 1. In a telephone exchange system, a line, a relay, means for associating said relay with said line whereby said relay is responsive to signaling current of a predetermined character, and means for altering the association of said relay with said line whereby said relay functions as a vibrator to transmit signaling current of said character out over said line, said relay having short-circuiting contacts for causing its vibratory operation.

2. In a telephone exchange system, a line,

a relay, inductive means for associating said relay with said line whereby said relay is re sponsive to incoming signaling current of a predetermined character, and means for altering the association of said relay with said inductive means whereby said relay functions as a vibrator to generate and transmit signaling current of said character out over said line. V V

3. In a telephone exchange system, a line, a relay, means controlled over contacts of said relay, a source of current, means for associating the winding of said relay with said linewher-eby said relay is responsive to incoming signaling current of a predetermined character, and means for switching said relay winding into a circuit with said source ofeurrent and the saidrelay contacts into a short-circuit about-the windings of said relay whereby,- said, relay functions as a vibrator to transmit signaling current of said character out over said line. I

4:. In a telephone exchange system, a line,

l i. U

a relay, means controlled over contacts of said relay, a source at current, inductive means, means for associating the winding of said relay with said line whereby said relay is responsive to incoming signaling current of a predetermined character, and means for switching said relay winding into circuit with said source and into association with said inductive means and said contacts into a shunt about the winding of said relay whereby said relay functions as a vibrator to generate and transmit signaling current of said character out over said line.

5. In a telephone exchange system, a line, a relay, means controlled over contacts of said relay, a source of current, an induction coil, means for associating the. winding of said relay with said line whereby said relay is responsive to incoming signaling current of a predetermined character, and means for switching said relay winding into circuit with said source and said induction coil and said contacts into a shunt about the winding of said relay whereby said relay functions as a vibrator to generate and transmit signaling current 01": said character out over said line,

6. In a telephone exchange system, a line divided into a first and a second section, means associated with said first section and responsive to signaling current incoming thereover, and means controlled thereby for generating and transmitting signaling current out over the second section of said line, said means comprising a vibrator relay having short-circuiting contacts.

7. In a telephone exchange system, a line divided into a first and a second section, means associated wit-h said first section and responsive to signaling current of one character incoming thereover, a vibrator relay responsive to signaling current of a second character incoming over the second section of said line, a source of signaling current of said first character, means responsiveto said relay for applying current from said source to the first section of said line, and means responsive to said first means for generating and transmitting signaling current of said second character out over the second section of said line, said last means comprising said relay and inductive means.

8. In a telephone exchange system, a line,

divided into a first and a second section, vibrator relay associated with each section of said line, said relays being adjusted to be responsive respectively to signaling current of ClllIQI'QIlt characters incoming over the respective sections of said line, and means for generating and transmitting signaling current of said different characters out over the sections of said line, each of said means comprising one of said relays and inductive means.

9. In a telephone exchange system, a line divided into a first and a second section, and means responsive to signaling current of one character incoming over the first section of said line for applying current of another character to the second section of said line, and vice versa, said means comprising two vibrator relays and inductive means, each of said relays adapted to function either as a responsive device or in conjunction with said inductive means as a current generating device.

10. In a telephone exchange system, a line divided into a first and a second section, a differently tuned relay normally associated with each section of said line, inductive means, and means under the control of each of said relays when responding to signaling current of the frequency to which it is tuned incoming over the associated section of: said line for altering the association of the other relay with its corresponding section of the line whereby said latter relay functions in conjunction with said inductive means to generate and transmit signaling current of the frequency to which it is tuned to the associated section of the line.

11. In a signaling system, a line over which signaling current may be transmitted, in both directions, a device responsive at one time as a relay to alternating current flowing over said line from a distant point, and means co-operating with said device to render said device effective at another time as a converter to generate and transmit alternating current out over said line to the distant point.

In witness whereof, I hereunto subscribe my name this 16th day of October A. 1)., 1924c.

HENRY W. ONEILL.

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