US2761011A - Intercommunication system - Google Patents

Intercommunication system Download PDF

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Publication number
US2761011A
US2761011A US205052A US20505251A US2761011A US 2761011 A US2761011 A US 2761011A US 205052 A US205052 A US 205052A US 20505251 A US20505251 A US 20505251A US 2761011 A US2761011 A US 2761011A
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United States
Prior art keywords
amplifier
tube
station
lead
microphone
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Expired - Lifetime
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US205052A
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English (en)
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Hardy Rene
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SEPCO
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SEPCO
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Priority to US205052A priority patent/US2761011A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M9/00—Arrangements for interconnection not involving centralised switching
    • H04M9/08—Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M9/00—Arrangements for interconnection not involving centralised switching
    • H04M9/001—Two-way communication systems between a limited number of parties

Definitions

  • the microphone at each station is normally cut' OE and:
  • operation on the part of the listener or person speaking which does not require the microphone and speaker at the respective stations to be spaced widely apart, which will permit normal conversation between the installation useless for normal ice parties so that either of. them may interrupt the other at any time. and will dependably reproduce the intelligence or speech without clipping or distortion thereof.
  • a microphone at a local station connected to a speaker at a remote station and a speaker at a local station connected to a microphone at the remote station with a speech amplifier associated with each of the microphone speaker combinations.
  • Each of the speech. amplifiers is normally de-energized and has a control amplifier associated therewith, and the amplifiers are so connected that upon an audio signal input into one of the control amplifiers it will energize the associated speech amplifier and retain the other speech amplifier. de-energized, yet upon an audio signal input into the second control amplifier of greater amplitude than that intothe first control amplifier, the first speech amplifier will be cut off and the second speech amplifier energized.
  • the speech amplifier associated with each of the microphone-speaker combinations is rendered inoperati've'by the lack of sufiicient potential on one of the elements of at least-one of its vacuum tubes.
  • the control amplifier associated therewith is designed to provide, when actuated by the signal into the associated microphone, a sufiiciently high potential on such vacuum tube element to cause the stage in which it is included to function, thereby rendering the speech amplifier operative.
  • the control amplifier is also designed to apply a disabling potential to the output stage of the control amplifier associatedwith the speech amplifier controlling the other microphone-speaker combination so that said control amplifier will not deliver an energizing potential to said speech amplifier and hence the latter will remain inoperative.
  • control amplifiers are also so designed, that eventhough the output stage of one of said control amplifiers may have such disabling potential applied thereto, as above described, if the input signal to the output stage of said disabled control amplifier should be sufliciently high, such as would occur if the person talking into the microphone associated with said disabled amplifier should speak in a loud voice, the 'cut-oif' condition of such output stage would be overcome and such output stage would function to provide a voltage which would actuate the speech amplifier associated therewith and disable the output stage associated with the other control amplifier. As a result, either of the parties" speaking may take, over the conversation by' merelyspeaking in a voice. louder than the other party.
  • the speech amplifiers associated with each of the microphone-speaker combinations. is rendered inoperative by having the screengrid of the input stage thereof normally'either' at zero potential or at such a low potential that the tube will not function properly.
  • the screen grid is connected to the 1 plate ofzthe' output stage of the control amplifier associated with said speech amplifier, said output stage being normally energized so that its plate voltage by reason of the voltage drop across the associated plate load resistor will be at a relatively low value, not sutficient' for normal operation of the input tube of the speech amplifier.
  • the output 'stage' of the control amplifier is controlled by suitable circuits which include an input or amplifier stage fed by the microphone associated with the speech amplifier.
  • the output of such input stage is desirably rectified to produce a negative signal which, when impressed on the grid of the output tube of the control amplifier will cut the latter ofi;
  • the plate potential will rise rapidly to a point suflicient to energize the input stage of the speech amplifier so t-h-atthe latter'will function properly.
  • the plate of the output tube of the first named control amplifier is connected to the control grid of the output tube of the control amplifier associated with said last named speech amplifier. Consequently, when the output tube of the first named control amplifier is cut off, a relatively high positive potential will be applied to the control grid of the output tube of the last named control amplifier so that the latter will continue to conduct thereby preventing any likelihood of sufficient plate potential being developed by such tube which would render operative the speech amplifier controlled thereby.
  • Fig. 1 is a detailed circuit diagram of the communication system
  • Fig. 2 is a circuit diagram of a switching arrangement which may be utilized with the system shown in Fig. 1.
  • the system desirably includes a local station, preferably a master station having its own amplifiers.
  • the local station has a microphone connected through a conven tional microphone transformer 11 and lead 12 to the control grid 13 of vacuum tube 14 in the input stage of the associated speech amplifier 15.
  • Vacuum tube 14 which illustratively is a conventional pentode, has its plate 16 connected through coupling capacitor 17 to potentiometer 18 and thence through the movable arm 19 of such potentiometer to the control grid 22 of a vacuum tube 23 which also desirably is a pentode, connected in conventional manner.
  • the plate 24 of tube 23 is connected by lead 25 to a speaker transformer 26, the output of which is connected by leads 27 to a speaker 28 at a remote station which illustratively is a secondary station having no amplifier units associated therewith.
  • one of the elements of the input vacuum tube 14, illustratively the screen grid 32. thereof, is not supplied with sufficient potential and hence the input stage of such amplifier in which tube 14 is incorporated, will not function or will function with very low gain so that the speech amplifier will be inoperative.
  • the control amplifier 33 Associated with the speech amplifier 15 is the control amplifier 33, which as shown in Fig. 1 has an input tube 34, illustrating a pentode connected in conventional manner, the control grid 35 of which is connected by lead 36 to the output of the microphone transformer 11.
  • the tube 34 which functions as a conventional pentode amplifier tube, has its plate 37 connected by lead 38 through coupling capacitor 39 to the potentiometer 42, the movable arm 43 of which is connected by lead 44 to the control grid 45 of an amplifier tube 46, illustratively a triode connected in conventional manner.
  • the plate 47 of tube 46 is connected through coupling capacitor 48 and lead 49 to the plate 52 of a diode detector tube 53, the cathode 54 of which is connected to the movable arm 55 of a potentiometer 56, the latter being connected between a source of potential 57 and ground.
  • the plate 52 of diode 53 is also connected by lead 58 to resistors 59 and 62,. which are connected respectively by leads 63, 64 and lead 65 to opposite sides of a capacitor 66 and by lead 67 to ground.
  • Lead 65 is also connected by lead 68 to the control grid 69 of the output tube 72 of the control amplifier 33, said tube 72 illustratively being a triode connected in conventional manner as to be normally conducting.
  • the cathode 73 of tube 72 is connected to the movable arm 74 of a potentiometer 75 which is positioned between a source of potential 76 and ground.
  • the plate '77 of tube 72 is connected through load resistor 78 to a source of potential 79 and also by lead 82 through resistor 83 and lead 84 to the screen grid 32 of tube 14 in speech amplifier 15, a capacitor 86 being associated with the resistor 83 in conventional manner to prevent the varying audio signals from affecting the positive screen grid potential,
  • Speech amplifier 87 at the local station is identical to the speech amplifier 15, it is not shown in detail being diagrammatically represented by the block outline and has a microphone 99 at the secondary station asso ciated with the speaker 91 at the local station.
  • Speech amplifier 87 in manner similar to speech amplifier 15, feeds the input stage of a control amplifier similar to control amplifier 33 and diagrammatically represented by the block 92 and, through circuits identical to those previously described in control amplifier 33 (and bearing the same reference numerals primed), feeds the control grid 93 of the output tube 94 of said control amplifier 92.
  • the plate 77 of 'tube 72 is connected by lead 95 through resistor 96 to the control grid 93 of tube 94 and in like manner the plate 97 of tube 94 is connected by lead 98 through resistor 99 to the control grid 69 of tube 72.
  • the plate 97 of tube 94 is also connected through a plate load resistor 101 to a source of potential 102 and by lead 103, resistor 104 and lead 165 to the screen grid (not shown) of the vacuum tube in the input stage of speech amplifier 87.
  • Tube 46 will also amplify the signal and such signal will be detected and rectified by the diode 53, which will permit the positive portions of the signal to pass to ground and the negative portions of the signal, which will be filtered by the network 59, 62 and 66, will be impressed upon the control grid 69 of the normally conducting output tube 72.
  • Tube 72 is normally biased at such a point that it will not be cut off by relatively weak signals, such as from outside noises which may be picked up by the microphone 16, and impressed on the grid 69 of tube 72 through the circuits of the control amplifier above described.
  • the negative input to the grid 69 of tube 72 caused by the detection and amplification above described of the voice input, will cause the tube 72 to cut ofi.
  • the party at the remote station should desire to break into the conversation, he need merely talk into-his microphone 90 in a voice louder than the amplitude at which the first party is speaking.
  • the input stage of the control amplifier'92 associated with the" secand speech. amplifier 87 will amplify such loud voice in. the manner previously described with respect-to control amplifier 33 and the signal: will be detected and rectified by the diode 53 so that a negative signal of relatively great amplitude will be: impressed on the control grid 93 of vacutun tube 94 of the control amplifier 921 This negative: signal will be: sufficient to overcome the positive bias on such tube. afiected both through potentiometer 75 and the connection from the platev 77 of vacuum tube 72 to the control grid 93-.
  • vacuum tube 94 will be cut off causing. the positive voltage on the plate 97 thereof to rise rapidly. and? as such positive voltage will be impressed” on the' control grid 69 of vacuum tube 72throughlead 98" and resistor 99, such positive voltage will tend to make vacuum tube 72 conduct heavily as it will overcome the negative rectified signal from diode 53; As aresult of the" voltage drop across: plate load resistor 78 of vacuum tube 72, the voltage on plate 77 of tube 72 will: drop.v Hence, the positive bias through lead-.95 and resistor 96 to control grid 93 of tube-94will be reduced, thereby rendering such tube less. conductive until it finally'cuts. off. At this time the voltage on: the plate of tube 94 will be very high and consequently the positive voltage on: the grid 69 of tube 72 will be. sufiicient so: that said tube. will conduct strongly.
  • the second party may then speak in a normal voice for continued conversation.
  • the operations above: described occur very rapidly, it is. apparent that as far as the parties are concerned they will. be: maintaining a conversation that approximates almost: a face to face meeting and either may interrupt the; other. as desired by merely speaking in a louder voice.
  • the circuitsherein described could bev incorporated in a systemin which the local station is a master station as shown having amplifiers associated therewith and having a number of remote stations. connected to thelocal station, which remote stationsv may also be master stations havingtheir own amplifiers, or secondary stations without amplifiers.- In such a system it is desirable that the party at the local: station be able to call one or more of the remote stations with but a few simple manual operations before starting the conversation and thereafter hold a.conversation with the remote station or stations called. It is also desirable that either the secondary or master remote stations be able to call the local master station and that suchi'conversation also may be limited by the local master station to only itself and the station calling.
  • the master local station has the speech amplifiers 15 and 87 andthecontrolamplifiers 33 and 92 associated therewith, the control amplifiers being diagrammatically represented. by the single block outline.
  • Speech amplifier. 15 which has the microphone 10' associated-therewith is connected by leads 111 and 1 12 to contact 113 of a double pole double throw switch 114 of the push button type, the contact 115- associated with contact 113 being connected by lead 116 to-terminal117.
  • the speech amplifier87 at the local master station which has the speaker 91 associated therewith, has its input connected.
  • a remote master station may readily be connected to thelocal master stationiby means of transmission lines 151' and: 152 connecting the terminals 117, 117 and 139, 139'.
  • the remote master station shown on the right hand side of Fig. 2 is'identical to the'remote-master station shown on theleft hand side ofFig. 1' it Will not be described in detail, parts corresponding to the already described local master station having the same reference numerals primed.
  • thecircuit shown in the lower'part of Fig. 2. is desirably provided.
  • a second double pole double throw switch 153 also desirably'of the pushbntton type is'provided at the local station; the contact 154 of said switch beingcom nected. by lead 155 through resistor 156, lamp 157 and lead 158 to the junction between lamp 145 and buzzer 147.
  • the contact 159 associated with contact 154 is connected. by lead: 161 to contact 162 of switch 153 and also by lead 163 to terminal 164, the contact 165 associated with contact 162 being connected by leads 166- and 167 to the junction 168 between leads 134-and 135.
  • the contact 169 of. switch 153- is connected by leads 1571 and 17.2 to the junction 173 between leads 111 and 112, and the contact 174 associated with contact'1'69 is connected by lead 175 to terminal 176.
  • the remote-secondary station shown in Fig. 2 desirably comprises the microphone 90showu in Fig. 1',.connected inconventional manner and having a lead 177 connected to contact178 of a single pole double throw switch 179;
  • the associated contactt181 of said switch is connected by lead.182 to a buzzer 183 and thence to ground.
  • the movable. arm 184 of. switch 179-which illustratively engages contact 181, is connected by lead 185 to contact 186 of asingle pole double throw switch 187.
  • the movable arm 188 of switch. 187 which normally engages contact 186 is connected by lead 189 to terminal 164' of said secondary station.
  • the other contact 192 of switch 187 is connected by lead 193 to terminal 194, and the speaker 28 of said secondary station, which is connected in conventional manner, is connected by lead 195' to terminal 176'.
  • the remote sec ondary station is connected to the local master station by means of transmission lines 196 and 197 and 198' which connect the terminals 164, 164'; 176, 176 and1'94, 194 respectively, the terminal: 194 at the local station being connected by lead 199 to lead 129 as at 201.
  • the local master station has been shown with provision for connection thereto of. but two remote stations, Le, a master station and a secondary station, it is of course to be understood that any suitable number of remote stations, either master or secondary could be con;
  • Such party may then press down on the push button of switch 114 which will cause the contact arm 202 thereof to break the circuit between contacts 142 and 143' and close the circuit across contacts 136 and 137 and also move the contact arm 203 of switch 114 across the contacts 113 and 115' to bridge the latter.
  • the lamp 145 and buzzer 145 will be cut out of circuit and a circuit will be completed from the terminals 117 and 139' of the remote master station to the speaker and microphone 91' and 10' thereof respectively.
  • the party at the remote master station may then speak into the microphone 10' and answer the call.
  • the circuit for microphone 10 will be through lead 125', contact 126 of switch 127, contact arm 133' normally engaging said contact 126, leads 134' and 135', n
  • the party at the local master station desires to call the remote secondary station he need merely first press the push button associated with switch 153 to move the movable contact arms 211 and 212 thereof to bridge contacts 162, 165 and 169, 174 respectively. He then would press the key 127 to move the movable contact arm 133 thereof into engagement with contact 128.
  • the key 127 at the local master station ordinarily need not be used to call the secondary station, for upon pressing of the push button of switch 114, for example, at the local master station, a circuit will be completed to the speaker at the secondary station.
  • the party at the master station does not wish to call out into his microphone he can give warning that he is desiring to call by the use of such key.
  • the party at the master station on hearing said buzzer need merely press the push button associated with the illuminated lamp 157 to complete the circuits heretofore described from microphone 10 and speaker 91 at the master station to speaker 28 and microphone at the secondary station.
  • a communication system comprising two speech amplifiers, each having an amplifier tube having a screen grid, two normally conducting control amplifiers connected respectively to said speech amplifiers, a microphone designed to receive an audio signal and connected to the input of each of said speech amplifiers and its associated control amplifier, a speaker connected to the output of said speech amplifiers, each of said control amplifiers having a normally conducting stage having a tube with a plate load resistor, means connecting the plates of said tubes to the screen grids of the associated speech amplifier respectively, means in each of said control amplifiers, actuated by the signal into the associated microphone to cut off the normally conducting tube, whereby upon drop of the potential across the associated load resistor, the voltage on the plate will rise and such potential will be supplied to the screen grid of the amplifier tube of the associated speech amplifier to render said tube and said speech amplifier operative, and means controlled by said rising plate potential of one of said control amplifiers to retain the speech amplifier associated with the other control amplifier inoperative, whereby upon a signal into one of said microphones of greater intensity than the signal into the other of said microphones, the
  • each of said control amplifiers comprises a normally conducting input stage, a diode detector associated with the output of said input stage and connected to rectify the signal therefrom and pass the negative portion thereof, the output of said diode being connected to the control grid of the normally conducting stage of said control amplifier whereby said negative signal will cutoff said tube to cause the plate potential thereof to rise.
  • each of the connections between the plate of the normally conducting stage of said control amplifier and the screen grid of the associated speech amplifier includes a voltage dropping resistor.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)
US205052A 1951-01-09 1951-01-09 Intercommunication system Expired - Lifetime US2761011A (en)

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Application Number Priority Date Filing Date Title
BE498982D BE498982A (sr) 1951-01-09
US205052A US2761011A (en) 1951-01-09 1951-01-09 Intercommunication system

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2850569A (en) * 1953-09-07 1958-09-02 Defensor A G Electric arrangement for speech transmission in two directions

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2205142A (en) * 1937-02-03 1940-06-18 Holtzer Cabot Electric Co Loudspeaking telephone system
US2319680A (en) * 1940-12-02 1943-05-18 Hasenberg Werner Simultaneous transmitting and receiving system with electronic change-over device
US2323307A (en) * 1940-07-01 1943-07-06 Webster Electric Co Inc Communication system
US2347080A (en) * 1942-12-14 1944-04-18 Webster Electric Co Inc Communication system
US2515726A (en) * 1945-09-24 1950-07-18 Automatic Elect Lab Intercommunicating system
US2536820A (en) * 1948-09-17 1951-01-02 Prahm Louis Two-way communication system
US2545466A (en) * 1948-07-10 1951-03-20 Le Teleampliphone Soc Loud-speaker telephone installation
US2545476A (en) * 1948-01-26 1951-03-20 Levy Jaeques Loud-speaker telephone intercommunication system
US2623949A (en) * 1949-06-08 1952-12-30 Le Teleampliphone Soc Two-way loud-speaker telephone installation

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2205142A (en) * 1937-02-03 1940-06-18 Holtzer Cabot Electric Co Loudspeaking telephone system
US2323307A (en) * 1940-07-01 1943-07-06 Webster Electric Co Inc Communication system
US2319680A (en) * 1940-12-02 1943-05-18 Hasenberg Werner Simultaneous transmitting and receiving system with electronic change-over device
US2347080A (en) * 1942-12-14 1944-04-18 Webster Electric Co Inc Communication system
US2515726A (en) * 1945-09-24 1950-07-18 Automatic Elect Lab Intercommunicating system
US2545476A (en) * 1948-01-26 1951-03-20 Levy Jaeques Loud-speaker telephone intercommunication system
US2545466A (en) * 1948-07-10 1951-03-20 Le Teleampliphone Soc Loud-speaker telephone installation
US2536820A (en) * 1948-09-17 1951-01-02 Prahm Louis Two-way communication system
US2623949A (en) * 1949-06-08 1952-12-30 Le Teleampliphone Soc Two-way loud-speaker telephone installation

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2850569A (en) * 1953-09-07 1958-09-02 Defensor A G Electric arrangement for speech transmission in two directions

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