US3130273A - Intercommunication system - Google Patents

Description

April 1964 w. J. NOECKER INTERCOMMUNICTION SYSTEM Filed 00t. 1, 1958 WILFRED J. NQECKER INVENTOR.

BY yi United States Patent 3,13%),273 INIERCONLMUNCATIQN SYSTEM Wilfred J. Noecirer, 4217 Dedge St., Omaha, Nebr. Filed Oct. 1, 1958, Sar. No. 764,548 3 Claims. (Cl. 179-40) This inventon relates to intercommunication systems and more particularly it is an object of this inventon to provide an intercommunication system which is more compact.

Heretofore the custom in the industry has been to have an amplifier at each station. This is common in the allmaster system. In such amplifiers in order to obtain a more compact system, it has been the recent trend to substitute transistors for these tubes. However, in this substitution, costs go up sharply.

It is, therefore, an object of my inventon to provide a system in which there are neither transistors nor tubes at the separate stations. I accomplish this by eliminating amplifiers at each station and by using instead a central amplifier, remotely located in the basement or some outof-the-way place.

I realize that the use of the central amplified is by itself not new, however, my inventon resides chiefly in a new combination of elements, each of which are not new, yet a combination which has never before been conceived, although I realize that certain individual parts of my new combination have heretofore been associated together.

Though the use of relays and manual switching have both been used heretofore with central amplifier systems, these have never before been combined with certain other features of my inventon necessary to arrive at the cooperative advantages.

One reason for the value of relays, as I use thern, lies in the fact that a switch in my system which is open at one station can be closed from another station. A chief disadvantage of a prior art manual system lies in the fact that a switch closed on one station cannot be opened from another station. It is the human error that operators will leave their switch closed at the end of their conversation and this renders the entire system inoperative or at least undesirable squeaks, squawks, and squeels occur When someone happens to select the same station that has been left in disengagement.

Therefore, it is an object of this inventon to provide a relay operated system by means of which a switch at one station can be opened from another station so that in order to insure privacy of conversation between two stations, it is then not necessary to first walk all over a building, up and downstairs, to try to find out who left switches closed at some unknown station.

Other and further objects and advantages of the present inventon will be apparent from the following detailed description, drawings and claims, the scope of the inventon not being limited to the drawings themselves as the drawings are only for the purpose of illustraing a way in which the principles of this inventon can be applied.

Other embodiments of the inventon utilizing the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present inventon and the purview of the appended claims.

In the drawings:

FIG. 1 is a diagram of the circuit of the intercommunication system of this inventon; and

FIG. 2 is a broken away portion of the circuit which represents the holding portion of the circuit of my invention.

The intercommunication system of my inventon comprises several main sections, a first section, generally indicated at 1, and containing central relays and amplifier,

later described, a plurality of master station sections, which two are shown for purposes of illustration, namely, master station 1 shown in a space numbered 2 and separate by dotted lines and master station 2 shown between dotted lines at 3.

At various places in the following description certain relays will be mentioned each one having a plurality of contacts or armatures which are in a wiring diagram of FIGURE 1 at points spaced apart from the relay coil itself. For convenience of reference, each coil number is given a letter after it and each contact or armature that is actuated by that relay coil has the same letter after its number.

Relays A, B, C, and D each have one coil and five contacts. Relays E and F each have one coil and two and six contacts respectively.

In the master station 1 there are two switches 11 and 12 of which switch 11 is, of course, not used to call station No. 1 and S0 is used to put station 1 in a stand-by condition after a call has been made, switch No. 11 also serving the purpose of all-call, namely calling all other stations, in this illustraton, the only other station being station No. 2. The switch 12 is actually a manual control switch.

In this master station 2 there are two switches 21 and 22. The switch 21 is actually a manual control switch.

When it is desired for master station No. 1 to talk to master station No. 2, the operator at station No. 1 closes his switch or manual control switch 12 placing the movable terminal 5ii thereof in contact with a terminal 52 connected to a conductor 54 which is connected to a terminal 55 of a relay coil 58D.

The other terminal 59 of the coil 58D is connected to a common conductor 60 which is connected to a stationary relay contact 62E which is normally engaged by a relay armature contact 64E, usually closed, which latter is connected to a conductor 68 which leads to the positive terminal 70 of the battery or other D.C. source or otherwise can lead to a terminal of an A.C. source.

The movable terminal 50 of the switch 12 is connected to a conductor 72, which leads to a terminal 74 of an imput relay coil 7613. The other terminal 78 of the coil 7 GB is connected to the negative terminal 80 of the battery or other D.C. or A.C. source of current or is otherwise connected to the other terminal of an alternating curent source.

As thus described a circuit is complete and electricity flows through the coil 76B, the conductor 72, the switch 12, the line 54, the relay coil 53D, the normally closed relay contacts 6213 and 64E and to the line 68 leading to the positive terminal 7 0.

This current flow is instantaneous and also causes a current flow through a conductor 99 from the terminal 74 of relay 76B to an armature 92B which is the holding contact for the imput relay 76B. As the imput relay 76B is energized the armature 9213 closes against terminal 96B which latter is connected by a conductor 98 to a terminal 14343 of a talk-listen coil 102F. The other terminal 1434 of the talk-listen coil 102F is connected by a conductor 186 to a holding contact stationary terminal 108D.

At this point the terminal 108D is engaged by its armature 119D which latter is in closed position. The armature terminal 119D is connected by a conductor 111 to the line 54.

The holding contact 923, %B, the talk-listen coil 162F, and the relay contact 168D, D all form a holding circuit so that while the switch 12 remains closed the amount of currenbflowing through the talk-listen coil 102F is not suificient to throw the two armatures 1243F and 122F operated by the talk-listen relay coil 102. However, When the operator releases the switch 12 a full current flows through the talk-listen coil 192F whereby the armatures 120F and 122F are placed in contact with stationary contacts 124F and 126F respectively.

Before describing the remainder of the input and output circuit, it is to be explained that simultaneously with the flow of current through the coil 7613 and the closing of the armature 92B a second armature 130B, also operating from the pull of the coil 76B, thrown against the terminal 132B which latter is connected by conductor 134 to the stationary terminal 124F of amplifier 141.

T he input terminal 124F is at times in contact with the input armature 133F, which is connected to an input terminal 140 of an amplifier 141. The amplifier 141 has its other amplifier input ground terminal 143 connected by a conductor 142 to a general ground or chassis ground 144. The arhpl-ifier 141 also has an amplifier output ground terminal 145 connected by a wire 146 to the general or chassis gro und terminal 144. The signal is amplified in the mplifier 141 and is presented at the other amplifier output terminal 121 which is connected to the amplifier output armature 122F frorn which the current flows through a stationary terminal 126F with which it has been in Contact, through a conductor 156 to a conductor 158, the conductor 158 leading to a stationary terminal 160D which is at that time engaged by an armature 162D. It is understood that the armature 162D is controlled by the coil SD earlier described, which latter is the same coil that also controls the armature 110D.

The armature 162D is connected by a conductor 164 to a stationary terminal 166A, which latter is the normally closed stationary contact of an input signal relay having an arrnature 168A which latter is connected by conductor 170 to the electroacoustc transducer 174 of station No. 2. The other terminal of the electroacoustic transducer 174 is connected by a conductor 176 which leads to the common ground terminal 144.

When the operator at master station No. 1 desires to call master station No. 2, he first closes the switch12. He then speaks into the electroacoustic transducer 180 of Station 1 and the signal travels across on the conductor 182- connected to the speaker 180 and up to the armature 13013 which is then in a closed position against the terminal 132B. The current from terminal 13213 flows through the conductor 134 to the terminal 124F of one of the talk-listen relays, through the armature 120F thereof, and through the imput coil 140 of the amplifier 141 whereby the signal is amplified and transferred to the output terminal 121 of the an1plifier, then traveling through the armature 122F, through the stationary contact 126F, through the conductor 156, through the conductor 158, through the stationary terminal 160D, through the armature 162D, through the conductor 164 and the terminal 166A and the armature 168A, through the conductor 170, to the electroacbustic transducer 174 of master station No. 2.

As thus described the sound has been picked up at speaker 180 of master station No. 1 has been amplified and has been delivered to electroacoustic transducer 174 of master station No. 2 whereby a ome-way conver sation has so far been described.

In order for inaster station No. 1 to receive a reply trom station No. 2, all the operator at station No. 1 does is simply to reinove his finger from the switch 12 whereupon a much larger and full current flows through the talk-listen coil 102F, the current then being for the first time sufiicient to 'energize relays operated by the talk-listen coil 102F although asmall and weak current had earlier been flowing through the talk-listen coil 102F while the switch 12 was closed. Thereupon the only current path is no longer 'through the switch 12 but is instead through the negative terminal 80, through the coil 76B, the armature 92B, the coil 102F, the armature 110D, and through the coil '53D and from there through the armature '64E to the positive terminal 7 0.

This flowing of full current through the talk-listen coil 102F for the first time causes the armatures 120F and 122F to be operated whereupon armature F make s contact with terminal 1Z4F and armature 122F makes contact with a terminal 154 which is connected by wi1'e 127F with wire 134, thus placing the amplifier in a listen position. A signal then picked up by station No. 2, speaker 174 traVels along conductor through armature 168A, contact 166A, conductor 164, armature 162D, contact 160D, conductor 158, conductor 156, to contact 138 to armature 120F to the amplifier input terminal 140 and is then amplified and presented at the output terminal 121 flowing through the armature 122F to the stationary contact 127, through the conductor 134, through the contact 1323 and the armature 130B, through the conductor 182 and to the master station No. 1 elcctroacoustic transducer 180. A further conductor 184 of course leads from the electroacoustic transducer to the common ground 144.

As thus described we have established contact by pressing a button, spoken to the other station, released the button, and received a reply.

Conversation is further contnued by again pressing the manual switch 12 to repeat the same process of first speaking and then listening. It is understood that pesS- ing the manual switch a second time efiectively puts a short across the talk-listen coil 102F causing the talklisten coil 102F to be de-energized to the point of cusing the talk-listen coil armatures 120Fand 122F to drop back to the de-energized position, in which de-energized position the circuit is again available for talking from the speaker of station No. 1 to the speaker of the station No. 2.

After conversation has been completed through alternate pressing and releasing of the button 12 the system is placed in a standby position by pressing station No. 1 manual switch No. 11. This Causes current to flow from the negative battery terminal 80 through the coil 76B, through the conductor 72, through a movable contact of switch 11, throu-gh the stationary contact 192 of switch 11, which latter is connected to the conductor 194, in turn connected to a conductor 196, connected to a terminal 193 of a relay coil 200E which,has another terminal 202 connected to the conductor 68 which leads to the positive battery terminal 70.

As thus described When the relay coil 20015 is energized it opens the armature 64E away from stationary contact 62E placing the output relay coil 58Dout of circuit and de-energized whereby the armature 110D opens away from the contact 108D.

Now removal of one finger trom the manual switch of switch 190, inasrnuch as it has a spring-opened momentary manual switch control member, will cause the switch 190 to be opened whereby the relay coils 7613 and 58D are deenergized and also the talk-listen coil 102F is de energized, whereby the system is back to standby position ready for use by an operator at either station l, station 2, a sub-station not shown or any other stations which might be connected in a similar way as master sta tions, 1 and 2 or the sub-stations.

When it is desired to call trom station No. 2 to station No. 1, the operator at station No. 2 depresses the manual switch of momentary spring-opened switch 220 whereby current from the negative terminal 80 flows through a conductor 222 connected therewith, thrugh an input relay coil 226A, through a conductor 228 connected with the other terminal of the coil 226A, through the armature 220 connected with the conductor 228, through the stationary contact 230 of the switch 21, through a conductor 232 connected therewith, and to a terminal 234 of an output relay 236C and from the other terminal 238 of the output relay 23:6C, through a conductor 60 connected to the other terminal thereof through the contact 62E, through the closed armature 64E, through a conductor 68 connected thereto and to the positive terminal 70. The armature 64E is closed at that time because it is normally closed being only opened by energy from the cancel relay col 200E, as earlier mentioned.

As energy flows through the input relay col 226, it also flows through a conductor 240, connected to the wire 228 and also connected to an armature 242A which latter is then in a closed position being energized by the col 226, the current flowing through a stationary terminal 246, through a conductor 248, and to the terminal 100 of the talk-listen col to which the conductor 248 is connected.

The current continues to flow through the talk-listen col 102F, through the conductor 106, through the annature 2500 of an output relay which latter has received current through a conductor 252, the latter leading from the wire 106 to a stationary contact 254C, then contacted by the armature 250C. The current flows through the armature 250C and through a conductor 256 which latter is connected to the terminal 234 of the output relay col 236C and from there flows through the conductor 60, the armature 6415, the conductor 68, and to the positive power terminal 7 0.

The circuit is in the position for the operator of master station No. 2 to talk into lns electroacoustic transducer 174 so as to be heard through the speaker 130 of master station No. 1, as is now described.

The signal trom master station No. 2 flows from its electroacoustic transducer 174 through the conductor 170, through the armature 168A which is then in contact with a stationary terminal 270A connected by conductor 272 to the conductor 134, flowing trom there upwardly to a stationary terminal 138 and from there to the armature 120F, and through the input transformer 140.

The signal from the input terminal 140 is ampliiied and presented on the output terminal 121, fiowing then through the armature 122F, the contact 154, the conductor 156, the conductor 158 and from there to a conductor 273 connected to the conductor 153 and also connected to a stationary terminal 280C. The energy then flows through the contact 280, through an armature 282C, through a conductor 284, to a contact 2363, to the armature 1308 in contact therewith, through a conductor 182 and to the electroacoustic transducer 180 of master station No. 1.

The other switch 22 of master station No. 2, performing the same function as switch 11 of station No. 1, has a movable terminal 350 connected to the line 228 and a stationary terminal 352 connected to the wire 1%.

When it is necessary to locate someone in a building equipped with this system and it is not known at which station the man can be found, it is desirable to use the all-call circuit. This is accomplished, for example, by the operator stationed at No. 1 depressing button 190 closing switch 11 whereupon current flows from the negative terminal 73 through the conductor 72 through the switch 11, through the conductor 194, through the conductor 196 and to the terminal 198 of the cancel or allcall col 200E. It is to be understood that the col 200E serves the double purpose of cancelling an all-call.

Current rom the cancel and all-call col 200E passes through the terminal 202, the conductor 68 and into the positive battery terminal 70. Thus while the button 130 of the switch 11 is depressed, the operator of station No. 1 can talk into his electroacoustic transducer 180 and the signal is carried through the conductor 182, the armature 130B, the conductor 134, and to the armature 120F to the amplifier input terminal 140. The signal is amplified and delivered to the output terminal 147, going through the armature 122F, which is in its de-energized position, through terminal 126F and the conductor 156, and through a conductor 300 to a terminal 302 which is in contact with an armature 304 of an all-call relay switch, which latter is against the terminal 302 in energized position, being energized by the aJl-call col 200E.

Thus the amplified signal is carried by a conductor 306 connected to the armature 304 and to which is connected conductor 308D leading to a terminal 310, the armature 162D being in contact with the terminal 310 in de-energized position because of the lack of controlling energy in its controlling col 58D. The col 58 is at that time without controlling energy because the armature 64E is open.

Current from the de-energized armature 162D flows through the conductor 164, through the de-energizecl armature 168A, which is out of contact with the terminal 166A because the col 226A is de-energized and not seiected, through the conductor 170 to the master station No. 2 electroacoustic transducer 174, whereby anything said in master station No. 1 electroacoustic transducer is heard at master station No. 2 electroacoustic transducer 174.

At the same time current is flowing from the conductor 306 through the conductor 303D, and it is also flowing from the conductor 306 to the connected conductor 320 through an armature 282C, at the time de-energized because of lack of current in its controlling col 236, through the conductor 284, and to the terminal 286 which represents a dead end because the armature 130B is out of contact with the contact point 286 as the armature 130B is in energized position because current is fiowing through its col 76B as the col 7613 corresponds to the calling station.

The all-call possibilities of my system are almost never present in intercommunication systems although they are present in other commercial sound systems.

These all-call possibilities are made possible in my circuit because of the use of relays.

Referring to FIG. 2 a broken away portion of the circuit is there shown which represents the holding circuit of my invention and numerals thereon are the same as corresponding numerals of the general circuit of FIG. 1.

Referring to FIG. 2, a simplified circuit is there shown to illustrate the holding portion of the circuit. Various associated units are shown and given primed numerals to indicate their similarity to the corresponding unprimed numerals in FIG. 1, all parts operating the same as above described.

The circuit explanation and the drawings of the audio portion of my invention illustrate what is commonly known as an unbalanced type of system. This is done primarily for simplicity. It should be understood that less hum, and higher level of operation can be attained by breaking both sides of the audio line through the input and output relays and the talk listen relay: Breaking both sides of the audio line changes the system to a balanced type circuit, which does not require any additional inter-station wiring nor does it change the control circuit wiring, changing only the central unit.

From the foregoing specification it will become apparent that the invention disclosed will adequately accomplish the functions for which it has been designed and in an economical manner, and that its simplicity, accuracy, and case of operation are such as to provide a relatively inexpensive device, considering what it will accomplish, and that it will find an important place in the art to which it appertains when once placed on the market.

An auxiliary channel of any kind can be added to the circuit because of the unusual nature of the circuit. For example, a radio is shown at 370 and has two wires 372 and 374 connected to its output terminals.

The wire 372 leads to the ground at 144. The wire 374 leads to a stationary terminal 376 contacted by the allcall relay switch armature 304 when the latter is in de-energized position being energized by the all-call relay col 200E.

As thus described, it will be seen that the intercom munication of this invention fulfills the object hereinabove set forth providing a very inexpensive all-call feature, a feature normally present in only very expensive sound systems. Similarity of button sequence at each station for simplicity of elimination of confusion for instal 7 lation, operation and maintenance; and provides a system in which the release button at a station is easily found as it is the button corresponding to that station.

It is thought that persons skilled in the art to which the invention relates will be able to obtain a clear understanding of the invention after considering the description in connection with the drawings. Therefore, a more lengthy description is regarded as unnecessary.

Changes in shape, sze, and arrangement of details and parts such as come within the purview of the invention claimd may be resorted to in actual practice, if desired.

I claim:

1. In an intercommunication system, the combination of a plurality of master stations, each master station having an electroacoustic transducer with only one pair of conductors carrying the voice currents therefore, a manual control switch for every other master station controlling both the talking and listening with another master station, a manual release switch, a source of current, an electronic amplifier, a single talk listen relay having an operating coil and reversible switches controlled by said coil, circuit connections between said switches and said amplifier, circuit connections between said switches, said electroacoustic transducers and said source of current including relay operated switches selectively controlled by said manual control switches and connected in circuit with the operating coil of said talk listen relay,and means controlled by said manual release switches for deenergizing the operating coil of said talk listen relay, said deenergizing means comprising: a release relayhaving two relay switches comprising a first relay switch being normally closed and a second relay switch, the sourceof current being connected to said talk listen relay through the switch of said release relay, a circuit connecting said release switch with said manual release relay whereby the first normally closed relay switch disconnects said source of current trom said talk listen relay whereby the manual release of said release switch permits the normally closed switch to close but thereby maintaining the circuit in a stand-hy position and said second relay switch being normally open with respect to the all-call circuit whereby the second relay switch closes the all-call circuit whereby the master station corresponding to said release button can call all other master stations whereby need for manually closing the circuit to each electroacoustic transducer is eliminated by the closing of said open switch.

2. In an intercommunication system, the combination of a plurality of master stations, each master station having an electroacoustic transducer with only one pair of conductors carrying the voice currents therefore, a manual control switch for every ether master station controlling both the talking and listenng with another master station, a manual release switch, a source of current, an electronic amplifier, a single talk listen relay having an operating coil and reversible switches controlled by said coil, circuit connections between said switches and said amplifier, circuit connections between said switches, said electroacoustic transducers and said source of current including relay operated switches selectively controlled by said manual control switches and connected in circuit with the operating coil of said talk listen relay, and means controlled by said manual release switches fo1 deenergizing the operating coil of said talk listen relay, each station having a manual control switch for every station in the system, one of said manual switches at each station being the home switch, the home switch being connected to bcth the release and all-call circuits whereby since the home switch corresponding to a given station is not required for the said given station to talk to itself the home switch puts the system in all-call when it is depressed and when it is released puts the system in standby, the sequence of manual switches trom left to right at each station being the same as at every other station for simplicity and elimination of confusion both in installation operation and maintenance and whereby an operator accustomed to manual switches at one station will not be confusecl when operating a new station.

3. In an intercommunication systern, the combination of a plurality of master stations, each master station having an electroacoustic transducer with only one pair of conductors carrying the voice currents therefor, a manual control switch for every ether master station controlling both the talking and listening with another master station and a manual release switch, a source of current, an electronic amplifier, a single talk listen relay having an operatingcoil and reversible switches controlled by said coil, circuit connections between said reVersible switches and said amplifier, circuit connections between said reversole switches, said electroacoustic transducers and said source of current including relay operated switches selectively controlled by said manual control switches and connected in circuit with the operating coil of said talk listen relay, and means controlled hy said manual release switches for de-energizing the operating coil of said talk listen relay, said de-energizing means comprising: a release relay having a coil and a release relay switch normally closed, the source of current being connected to said talk listen relay through the switch of said release relay, a circuit connecting said manual release switches with said release relay whereby the normally closed switch of said release relay disconnects said source of current from said talk listen relay whereby the release of said manual release switches permt the normally closed release relay switch to open thereby maintaining the circuit in a stand-by condition.

Refereuces Cited in the file of this patent UNITED STATES PATENTS 2,254736 Fitzpatlick Sept. 2, 1941 2,275,405 Berhley Mar. 10, 1942 2,559,898 Plawczyk July 10, 1951

Claims (1)

1. IN AN INTERCOMMUNICATION SYSTEM, THE COMBINATION OF A PLURALITY OF MASTER STATIONS, EACH MASTER STATION HAVING AN ELECTROACOUSTIC TRANSDUCER WITH ONLY ONE PAIR OF CONDUCTORS CARRYING THE VOICE CURRENTS THEREFORE, A MANUAL CONTROL SWITCH FOR EVERY OTHER MASTER STATION CONTROLLING BOTH THE TALKING AND LISTENING WITH ANOTHER MASTER STATION, A MANUAL RELEASE SWITCH, A SOURCE OF CURRENT, AN ELECTRONIC AMPLIFIER, A SINGLE TALK LISTEN RELAY HAVING AN OPERATING COIL AND REVERSIBLE SWITCHES CONTROLLED BY SAID COIL, CIRCUIT CONNECTIONS BETWEEN SAID SWITCHES AND SAID AMPLIFIER, CIRCUIT CONNECTIONS BETWEEN SAID SWITCHES, SAID ELECTROACOUSTIC TRANSDUCERS AND SAID SOURCE OF CURRENT INCLUDING RELAY OPERATED SWITCHES SELECTIVELY CONTROLLED BY SAID MANUAL CONTROL SWITCHES AND CONNECTED IN CIRCUIT WITH THE OPERATING COIL OF SAID TALK LISTEN RELAY, AND MEANS CONTROLLED BY SAID MANUAL RELEASE SWITCHES FOR DEENERGIZING THE OPERATING COIL OF SAID TALK LISTEN RELAY, SAID DEENERGIZING MEANS COMPRISING: A RELEASE RELAY HAVING TWO RELAY SWITCHES COMPRISING A FIRST RELAY SWITCH BEING NORMALLY CLOSED AND A SECOND RELAY SWITCH, THE SOURCE OF CURRENT BEING CONNECTED TO SAID TALK LISTEN RELAY THROUGH THE SWITCH OF SAID RELEASE RELAY, A CIRCUIT CONNECTING SAID RELEASE SWITCH WITH SAID MANUAL RELEASE RELAY WHEREBY THE FIRST NORMALLY CLOSED RELAY SWITCH DISCONNECTS SAID SOURCE OF CURRENT FROM SAID TALK LISTEN RELAY WHEREBY THE MANUAL RELEASE OF SAID RELEASE SWITCH PERMITS THE NORMALLY CLOSED SWITCH TO CLOSE BUT THEREBY MAINTAINING THE CIRCUIT IN A STAND-BY POSITION AND SAID SECOND RELAY SWITCH BEING NORMALLY OPEN WITH RESPECT TO THE ALL-CALL CIRCUIT WHEREBY THE SECOND RELAY SWITCH CLOSES THE ALL-CALL CIRCUIT WHEREBY THE MASTER STATION CORRESPONDING TO SAID RELEASE BUTTON CAN CALL ALL OTHER MASTER STATIONS WHEREBY NEED FOR MANUALLY CLOSING THE CIRCUIT TO EACH ELECTROACOUSTIC TRANSDUCER IS ELIMINATED BY THE CLOSING OF SAID OPEN SWITCH.

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