US2491263A - Ringing system for voice current repeaters - Google Patents

Description

Dec. 13, 1949 i R. H. HERRICK RINGING SYSTEM FOR VOICE CURRENT REPEATERS 2 she ets sheet 1 Filed Nov. 1, 1946 fillllll I. i J =2 55755 INVENTOR. ROSWELL H. HERRICK 202.501 hmu ATTORNEY Dec. 13, 1949 R. H. HERRICK RINGING SYSTEM FOR VOICE CURRENT REPEATERS' Filed NOV. 1, 1946 2 Sheets-Sheet 2 INVENTOR. ROSWELL H. HE RRICK ATTORNEY 4 Patented Dec. 13, 1949 B'EPE A'DERS Roswell H. Herrick, Lorain, Ohio, 'a's'sig'nor to Automatic Electric Laboratories, Inc, Chicago, 1-11.,a corporation of Delaware Application November 1, 1s4c,-.sem1 No, 707,100

The present invention relates in general to two-way transmission systems which employ separate amplifying means for transmitting signals 12 Claims. (01.179 84) in each direction and is concerned morefparticuany with new and useful improvements in. the

ringing systems of voice current repeaters.

It is an object of this invention to provide an improved ringing circuit for use "in a standard 22-type telephone repeater.

It is a further object of this invention to'utilize this new ringing circuit in conjunction with an improved method of frequency characteristic control in a standard 22-typ'e telephone repeater.

.A feature of this invention is to provide facilities in a repeater system of the 's'tandard 22- type telephone repeater. .for "transmitting ringing signals.

Another feature of the invention is the manner in whichv it is possible to ring, through 'on'eof the repeater channels and at the sam'e't'ime disable the complementary re eater channel thereby avoiding introduction of a singin disturbance in the complementary channel due to imperfect Iih'e balance.

It is still another teatdre of the invention to provide for a pair of leads connectedbetw'e'en the repeater and a local exchange thereby establishing a three exchange ringing system for use in a telephone system employing a repeater. 'In conjunction with this local circuit, another feature of this inventionis the manner. in which the by-pass circuit is used. as part of the ringing circuit.

Another ieature of the invention is the manner energized when the repeater system is removed from theline and the connection switched through .a by-pass channel'in the event of either a tube or powersupply iailure in the amplifier. The channel switching feature utilized in conjunction With this ringing control circuit is closed in Roswell H. Herricks co-pend'ing application SerialNo 711,962 .filed November 23, I946.

A further feature of the invention is the manher in which the ringing control, circuit is con- I nected to the. amplifiers at. their "input trian'sbest be understood by reference to the following.-

specification, taken in connection with the accompanying drawings, in which Figure 1 and Figure 2 when placed together as specified, illustrate a telephone repeater system having incorporated therein the features of the invention as briefly outlined above.

Referring now to the drawings, Figure 1 shows a conventional 22 type repeater, that is, there aretwo distinct one-way amplifiers arranged for use with an ordinary two-way telephone circuit. In addition to the repeater circuit, Figure 2 shows a ringing control circuit with conductors therebetween. The system, briefly consists of a re- ,pea tercircuit, a ringing control circuit and a re peater by-pass channel.

The repeater is comprised of an east and west position, an east-west channel, and west-east channel. The line terminals are located at the east and west positions. When the line circuit enters the east position from the east lines, it will be connected to the line terminals at the west position either through the repeater by-pass channel or the east-west channel. The line voice current entering the west position from the west line terminals will be connected to the east line terminals either through the west-east channel or the repeater bypass channel. The by-pass channel is comprised of contacts I and 9,, conductors 52 and 53, and contacts 22 and 24. The east-west channel consists of contacts 8 and l0, l2 and I4, repeating coil H, balancing pads l8, hybrid system l9, east-West amplifier, hybrid system 34, balancing pad 33, repeating coil 32,. contacts 2! and 29, and con tacts 23 and 25. The West-east channel is comprised of, contacts 23., 25 and 21, 29,repeater coil 32,, balance pads 33 and 35, balancing network .ior the west line 36, hybrid system 34, West east amplifier, hybrid system I9, balance pads 18 and 20., balance network for east line 2|, repeater coil ll, contacts 12 and i4 and contacts 8-and-l0.

The ringing control circuit consists of a two section triode tube i l, resistors 49, Ill, 14, i8, 18;, condensers 13, H13, H34, relays 'l, 2, 3., 4,5, and B and. their associated contacts. The contacts of relays Sand '6 are respectively 67., 69 and 68, 8. and are located in the ringing control circuit. Contacts 22,. 23., 24-, 25, H and 1, 8, 9, Hi, 12 are associated respectively with relays i and 4 and are connected in the repeater circuit at the easta-nd west positions. Relays .2 and 3, likewise, have their contacts 26, 2 1, .2-8, 29, 39, 3! and 1H, 12, 4-3, 14., i5, Iii respectively positioned in the repeater circuit. The ringing control cir- 3 cult also includes a ring-in east path associated with a control circuit for the ring-out west, and a ring-in West path associated with a control circuit for the ring-out east.

The ring-in east path includes the east-west channel from the east line terminals through the secondary winding of the input transformer 3'! at which point it passes through resistor 49,

conductor 62, resistor 70, and the grid of the.

lower section of tube 11, thereby causing the 4 of time that the incoming signal is effective. Relay 5 at its contacts 69 places a ground on the west repeater and thereby prevents the signal from initiating a singing disturbance within that circuit, and at its contacts 61 completes a circuit from the 115 volt source to relay 2. Relay 2 operates and at its contacts 2'! and 29 breaks the line connection to the repeater channels and at its contacts 28 and 30 in the west position applies a completion of the path from a source of potential 93 through relay 5 and the lower section of tube TI. The ring-out west control circuit, which is utilized in combination with the ring-in east path, consists of an alternating current source of potential 96, contact 61, and relay 2. The path for a ringing signal from the west position is through the west-east channel to the secondary Winding of the input transformer 80 and continues through resistor 14 conductor 63, the upper section of tube 11 and completes another path from the source of potential 93 through relay 6. The associated ring-out east control circuit is composed of contact 66, conductor 65, re-

lay 3, and an alternating current source of po- H tential 96.

Referring now more particularly to the operation of the system in the transmission of signals from the east position for repeated transmission to the west position. Assuming the repeater in the normally operated position relay in the east amplifier and relay 92 in the west amplifier 'will be energized. The current paths of the energizing circuits are essentially the anode circuits of the tubes and more specifically for relay 56, from the high voltage source 54 through the relay 5B, the

primary winding of the coupling transformer GE,

- the anode-cathode circuit of amplifier tube 33, the resistance at, and contact 56 to ground. An iden- -tical path is traceable for relay 92 in the west am- "plifier.

Relays 58 and 92, therefore, at their respective contacts 57 and 59 complete a circuit in the ringing control system from the high voltage source 99, through relays I and 4 in series, through resistor 19 in shunt of condenser 13 to ground.

Resistor 18 is of a predetermined value and effective in conjunction with either relays l and 4 or resistance 6! to supply the proper cathode bias to the two sections of tube l1. Relays l and 6 are therefore normally energized and at their respective contacts 23, 25 and 8, ll! connect the east and west lines to the repeater. Additionally, on

; operating, relays i and 4 remove the short-circuit imposed on the repeater systems at their contacts 27! and 12.

Assume a ringing signal is received over the east line from a distant exchange and passes over "contacts 8 and l0, l2 and I4, through repeating coil IT, balance pad [8, hybrid system Hi, to the input transformer 31, where the signal voltage 5 is increased for use with the high impedance grid circuit of tube 11. The signal, unable to pass further through the east-west amplifier circuit because of filter 4| travels over resistance 49 and conductor 62 to resistance 10 and ground. As a -result of the incoming signal received through I resistances 49 and 10, the required voltage is impressed upon the lower grid of tube l1 thereby The value of current through which is of an alternating current nature. A condenser IE4 is placed in parallel with relay 5 to maintain the relay energized for the entire period in a normal manner. feedback circuit impresses a large percentage of 20 cycle signal to the west line through contacts '23 and 25. This ringing signal is likewise transmitted to a local circuit by relay 2 at its contacts 26 and 3|. This circuit is employed in systems where the repeater system is located in the proximity of an exchange and through a predetermined code allows the operator at one exchange to contact either of the other two exchanges. Signals to the local line are transmitted by the east control circuit over the by-pass line when the ringing signal is applied at contacts is and [5 for a ring east signal. When the calling operator terminates the ringing signal, tube Tl again becomes non-conductive and stops the current supply to relay 5. Relay 5 releases and at its contact Bl breaks the holding circuit for relay 2. Relay 2 releases and at its contacts 26, 3i and 28, 3B terminates the ringing signal on the west and local lines.

When voice currents are imposed on the east line by the distant exchange, if the distance is at all large, a greatly attenuated voice current enters the repeating coil ll of the telephone repeater.

In lines of varied constructon, by means of key 168, it is possible to insert the conventional resistor balance pads l8 and 20 into the circuit whenever an imperfect balance exists over the requisite frequency range, thereby introducing a line loss which minimizes line discontinuities and permits overall balance. The voice current thereupon passes through a hybrid system I9, to the input transformer 3'1 of the east-west amplifier system, the input potentiometer gain control 38, amplifier tube 39, output transformer 16, filter 4], to hybrid system 34 at the west position, half of the energy being lost in the balancing network and the other half being transmitted through the balance pad system 33, the repeating coil 32 and over the west line via contacts 21, 29 and 23, 25.

The voice current value entering the amplifier tube 39 is controlled by the input potentiometer 38. The feedback connection from the plate passes through a condenser 82 and resistor 43 to a set of resistances 44 shunted by condenser 45 and to ground. Assuming a low voice frequency is transmitted to the amplifier, the tube will amplify Being a low frequency, the

the potential across the input potentiometer 38 and resistances 44. This potential being approximately out of phase with the input due to the tube characteristics, will be of a gain reducing nature and of a comparatively large value. With a voice current of higher frequency, however, a smaller amount of feedback will occur and cause greater amplification. The negative feedback is,

therefore, a function of the input frequency, the

gain reducing value being proportionally smaller with frequency increase. In view of the fact that telephone attenuation is such that the input to thereceiver normally decreases with frequency increase, this negative feedback method of control is extremely practical; The value of resistance required for different systems is a variable factor and likewise the rising frequency characteristic desired is dependent entirely upon the nected in the ringing control circuit in sucha manner that if anode current of either channel amplifier falls below the operating value, the relayassociated with. the failing system willdeenesgize, and thereupon break the circuits .for relays l and 4 which in turn rernovethe repeaters tronx the line at their assooiated'contacts 8, Wanda,

25 and connect the line terminals tethe by-1138155 channel at their contacts 1., il-and Z2, 24;. J-f-relay 59 deenergizes, it will light su pervisory lalnp 94 at its contact 55. Relay '92, ;at its contact 56 -will 'iilgewise light-lamp 434; if the anode circuit offi-ts-associated amplifier fails in any manner.

Voice currents initiated on the west lines will be transmitted hythe repeater through its westeast channel or toy-pass channel in-a similar manner to that signal transmitted through the eastwestchannel as .previously described. The ringi-ng signal in tiated on the west conductor passes over the west-east channel to the input trans; {former of the west-east amplifier. The signal then passes through resistance M, conductor 63, to resistor {it which with resistor [is effectiveas a voltage divider. A voltage of predetermined value isiimpressed upon the grid of the -second section o f-tube i! as aresult of. the incoming-signal received through resistors 14 and. 18 and therebycnengizes tube 11. Relay 6 energizes on 'the increased average anode currentfiow from source oi-potential 9 3 and at its contacts 66 completes a path from alternating currentsOurce-SB through relay 3 and atits contactstbplaces a ground on the east amplifier circuit. Relay} energizes and atits cont-acts T3 and I5 transmits a ring signal on the east line and at its contacts T2 and Mfbreaks the line connection to the .re-

posters and at its contacts H and 16 transmits a signal over the Joy-pass channel tofthe local .line circuit. It will be noted that the, ring-in east and ring-in westpaths are grounded respectively 'by the operation of relay 6 and relay 5 thereby averting. secondary line ringing eifects caused 'by imperfect line-balance.

ihe supervisory 'Itest key 100 when operated in "the downw'ard .lpos'i'tion removes ground from the anode'ircuit of tube 39 at its conta'c'tJ-B and insert resistance 48 in the anode cathode Circuit.

"Th-c 112. drop across-the resistance 48 places-a high negative potential on "the grid whereupon the anode current decreases and relay '50 de'e'nergi'z' es. Th-ebbj eat of "thisk'y' is't'o provide a simple ans "ec'on omlen 'reray a' 'a ifiubetes't ro'r the-ampune r. The key when operated in the upward cosinen ma es asiniil-ar. test on the western- 'pl1'fie'l'. When either relay d'ee'neigi'ZeS they "Will in turn lo're'ak the circuits "forrela'ys l "and 4 and insert equivalent resistance 6| in the cathode jcireuit of tube Tl. At their contacts H 'and 12,.re lays land 4 place a short circuit on the amplifiers which on reoperaition precludes a s'ingingdisturbance from entering 'the line'beeause o f the tem while the. testing operation is bemg consummated.

Relays 1'2. and 3 accomplish. a similar method of singing :precl-usive when they insert resistances 9,1 and 98. across the repeater systems at their respective contacts ml and Hill-during the ringing periods.

will henoted that the input signal to the ringing control circuit is received from the output connection of the amplifier transformers. In this manner the hybrid system balance is maintained and the signal potential is properly increased for use with the triode tube without thee/need of a second transformer the arrangement.

Terminals are located in the cathode circults of tubes 39and 82 as an aid to maintenance work and the grid; value of the amplifier tuhe may be readily. determined. by inserting a voltmeter between tenminal Fix and ground.

-A conventional :power supply. unit is used in combination with the -voicerepeaten The power supply unit is operated on a 115 volt, -60 circuit and includes a .power transformer with various an "outgoing line, an -amplifier "connected therea plifier and fsaid grid,"a second resistor, a

taps and a SE3 GT tube which with. the assoelated ci-rcuits is efiective to supply the desired 250; voltsou-rce, 23'6v1oltsource and the 6.3 volt source. 7 p p 1tv is to glee understood that various modifications rnayf he madein the-form of-this invention above described without.departing f-rom thespirit Of the invention as cited in the appended claims.

What is claimediS; 1 In a transmission system, an amplifier, a incoming and an ou-tgdingll'ine connectedtheremanagi control e ircuit connected tosaidlines including a vacuum tube normally nonconduetive, an incoming signal, amplifying .means 'in said amplifier ior amplifying. said. "incoming signal, said tube, rendered conductive said amplified signal on said incoming. line, :a source of signal current, means for transmitting. an outgoing sig- "nal from said 'source over said outgoingf line, .a relay "responsive .to said tube -being rendered conductive by. said 'incoming signal "to operate said means lto transmit'said outgoing signaland to disconnect said amplifier froin .saidioutg'oing line.

2. n claim as 'ciaimeain claim -1 in which there is third line. and in which; o eration or "said means also connects saidthird line to said source,

said out'go'ing signa'l,'thereby transmitted over *said outgoing and said third lines, a second-relay operated Thy said ampliher't Dneposition to conheel; said outgoingfline to said amplifier and in another position "to disconnect said outgoing Lli'ne rromisaiu amplifier and "to "connect said outgoing line to said third line, said means efiective to transmit 'a's'igna-l from saidjsourc'etofsaid outgoing and said third lines when said second relay is in either"ofsaidpositions.

3'. In a transmission system, an incoming line,

fbe'tw'een, a ringing;eircuit connected "to "said lines including-a 'vacuumtube having'a cathode andja g' riia'relayeonnected tosaid cathode, a'resistor, aifirst c'ireuit jforfc'onneeting said resistor between second circuit for con ecting said second resistor between said grid and ground, means including said "first circuit, "said first resistor, said second circuit and "said second I resistor. res onsive to the receipt. of a signal over said incoming line for am lving. a .potential Jto said ,grid to render said 'tiibe conductive said relayrespons ive to-saidltube becoming-conductive to thereby operate, and

extre amount or unbalance {in the-hybridsysvs meansY-for transmittin an r oute ing signalover said outgoing line responsive to the operation of said relay.

4. In a transmission system, a line circuit over which voice currents may be transmitted in either direction, one amplifier responsive to voice currents from one direction having an output circuit connection to said line circuit, another amplifier responsive to voice currents from the other direction having an output connection to said line circuit, and a ringing control circuit connected to said line circuit, said control circuit including a first relay, a means operated by a signal transmitted over the line from one of said directions to energize said first relay, a source of signal current, a second relay, means controlled by said first relay for operating said second relay, means responsive to the operation of said second relay for disconnecting the output circuit of said one amplifier from said line circuit and for transmitting a signal over said line circuit from said source of signal current in said one direction, a third relay, said means also responsive to a signal transmitted over said line in said other direction to energize said third relay, a fourth relay, means controlled by said third relay for operating said fourth relay, means responsive to the operation of said fourth relay for disconnecting the output circuit of said other amplifier from said line circuit and for transmitting a signal over said line circuit from said source in said other direction, thereby causing said ringing signals in either of said directions to by-pass said amplifiers.

5. In a transmission system, a pair of lines, a two way voice current repeater including a pair of amplifiers connecting said lines, a ringing control circuit connected to said repeater, including a two section vacuum tube, one section rendered conductive only on receipt of an incoming signal from one of said lines, the second section of said vacuum tube rendered conductive only on receipt of a second incoming signal from the other of said lines, a sourceof signal current, a relay operative to transmit a signal from said source over said other line independent of said amplifiers, a second relay operative to transmit a signal from said source over said one line independent of said amplifiers, a first means responsive to said first section of said tube being rendered conductive to operate said first relay, and a second means responsive to said second section of said tube being rendered conductive to operate said second relay.

6. In a transmission system, an incoming line and an outgoing line, a first voice current channel connected to said incoming and said outgoing line, a first amplifier in said channel having an input transformer, a second voice current channel connected to said incoming and said outgoing lines, a second amplifier in said second channel having an input transformer, a ringing circuit connected to said first channel, said second channel, said first amplifier input transformer and said second amplifier input transformer, said ringing circuit including a vacuum tube having one section comprised of a grid, an anode, and a cathode, and a second section comprised of a grid, an anode, and a cathode, a first resistor connected in series with said first amplifier input transformer and the grid of said first section of said tube, a second resistor connected between the grid of said first section of said tube and ground, said first resistor and said second resistor effective to apply a potential to said first section of said tube on receipt of a signal from said incoming line through said first channel and said first amplifier input transformer to render said first section of said tube conductive, a relay, a condenser in shunt of said relay, a source of signal current, means connected to said outgoing line for transmitting a signal from said source over said outgoing line, said relay responsive to said first section of said vacuum tube becoming conductive to operate said means, a third resistor connected in series with said second amplifier input transformer and said grid of said second section of said tube, a fourth resistor connected between said second grid and ground, said third resistor and said fourth resistor effective on receipt of a signal from said outgoing line through said second channel and said second amplifier input transformer to render said second section of said tube conductive, a second relay, a second condenser connected in shunt of said second relay, a second means connected to said incoming line for transmitting a signal from said source over said incoming line, said second relay responsive to said second section of said vacuum tube becoming conductive to operate said second means.

7. In a transmission system, a pair of lines, a two way voice current repeater, including a pair of amplifiers, connecting said lines, a first relay and a second relay connected in series and operative to remove said amplifiers from said line circuit, a third relay in and responsive to one of said amplifiers, a fourth relay in and responsive to the other of said amplifiers, said third and fourth relays operative to two positions, a ringing control circuit connected to said lines having a two section tube including a pair of cathodes,

a resistance, a second resistance, circuit means connecting said second resistance between ground and said cathodes to maintain the grid bias of said tube constant regardless of anode current value, means responsive to the operation of said third and fourth relays to one of said positions for connecting said first and second relays to said cathodes, means responsive to the operation of said third and fourth relays to the other of said positions for disconnecting said first and second relays from said cathodes and for connecting said first resistance to said cathodes, said first resistance thereby effective to prevent possible damage to said tube when said first and second relays are disconnected from said source.

8. In a transmission system, a bidirectional line circuit, a first voice current channel having input and output terminals connected to said line, an amplifier in said channel responsive to signals from one direction, a second voice current channel having input and output terminals connected to said line, an amplifier in said second channel responsive to signals from the other direction, a ringing control circuit connected to said line circuit including a two section vacuum tube, means for rendering one section of said tube conductive on receipt of a signal from said one direction on said input terminals of said first channel, a relay controlled by said one section of said tube, a source of ringing current, a first means connected to control said output terminals of said first channel controlled by said relay for transmitting from said source a signal in said other direction over said line, means for rendering the second section of said tube conductive on receipt of a signal from said other direction on said input terminals of said second. channel, a second relay controlled by said second section of said tube, a second means connected to control said output terminals of said second channel for transmitting a signal from said source in said one direction controlled by said second relay, said relays also operated to disconnect said channels from said line circuit.

9. A system as claimed in claim 5 in which there is an input transformer having secondary connections in said amplifier, said secondary connections being connected to said amplifier and also to said one section of said tube, thereby increasing the potential of said first incoming signal for energization of said tube and maintaining 1:,

a balance system in said repeater.

10. In a transmission system, a pair of lines, a two way voice current repeater including amplifiers connecting said lines, a by-pass circuit for connecting said lines independent of said repeater, a thermionic tube in one of said amplifiers, a relay in the plate circuit of said tube responsive to a fall of current in said circuit to disconnect said repeater from said lines and connect the by-pass circuit between said lines, a ring control plifiers connecting said lines, a by-pass circuit for connecting said lines independent of said repeater, means in one of said amplifiers operative to disconnect said repeater from said lines and connect the by-pass circuit between said lines, a ring control circuit connected to said lines, a relay, a vacuum tube in said control circuit responsive to a ringing signal over one of said lines for operating said relay, a second relay operated by said first relay for disconnecting said repeater from the lines, transmitting a ringing signal over the other line, and connecting said other line to the by-pass circuit.

12. In a system as claimed in claim 11, means responsive to the operation of said first relay for balancing said lines.

ROSWELL H. HERRICK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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