US2461945A - Receiver connection in electroacoustic duplex system - Google Patents

Receiver connection in electroacoustic duplex system Download PDF

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Publication number
US2461945A
US2461945A US573691A US57369145A US2461945A US 2461945 A US2461945 A US 2461945A US 573691 A US573691 A US 573691A US 57369145 A US57369145 A US 57369145A US 2461945 A US2461945 A US 2461945A
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United States
Prior art keywords
winding
transformer
amplifier
receiver
transducer
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Expired - Lifetime
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US573691A
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English (en)
Inventor
Tschumi Otto
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
FIRM AUTOPHON AG
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FIRM AUTOPHON AG
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Publication date
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Publication of US2461945A publication Critical patent/US2461945A/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

Definitions

  • FIG. 1 is a diagram of the subscribers end ofa telephone system embodying my invention.
  • Fig. '2 is a similar diagram of another embodiment.
  • the transducer LM works as a microphone, or as a loud-speaker according to whether it is connected to the input or to the output of an amplifier V.
  • the change-over from transmission to reception and vice versa is effected by switches ul and U2, which may be manually operated or controlled by a suitable relay (not shown).
  • switches ul and U2 which may be manually operated or controlled by a suitable relay (not shown).
  • switch ul With the circuitin condition for transmission of a signal, one lead of the transducer LM, acting as a microphone, is connected by switch ul with the input transformer E of the amplifier. V, the other lead going to ground.
  • the output transformer A is connected through the switch 142 and through a switch AS with a head set receiver H, which is located at the subscribers station.
  • the lead from the amplifier is connected to the midpoint of the winding of the receiver H.
  • One end of the said winding is connected through the distribution point a with one winding "of a'transformer LU, the other winding of which is connected with the terminals al and bl of the line.
  • the other end of the winding of the head set H is connected through a balance circuit N to ground.
  • the balance N consists of a circuit, the impedance of which correspond with that of the transformer LU loaded by the subscriber's line.
  • the winding of the head set receiver H is thus in efiect divided into two parts, hi and M, the lead from the amplifier V being connected to the mid point between the two parts of the winding.
  • the impedance of the path from the mid point of said winding, through the winding part hi, the transformer LU, to ground, is the same as that of the path from the mid-point of the winding through the winding part b2, and the balance circuit N to ground.
  • the amplified signal current from the transducer LM acting as a microphone is distributed into two equal portions in the receiver H, half of it flowing through the coil hi andthe other half flowing through the coil h2.
  • Fig. 2 The circuit shown in Fig. 2 is basically the same as that of Fig. 1 and the corresponding parts are designated by the same reference char acters. It difiers from the circuit of Fig. 1 in 2,461,945 I i v.: l
  • the location of the distribution point a is difierent, being located in the lead between the head set receiver H and the amplifier V.
  • Fig. 2 The arrangement shown in Fig. 2 is especial- ,ly advantageous when the subscribers station is working as a receiver and the sound energy output of the loud-speaker LM is so high as to cause the head-set receiver H to work as a microphone.
  • acoustic reaction might occur in the circuit of Fig. 1, since a part, of the current created by the head-set H acting as a microphone could flow through the winding coil hi, the distribution point a. and the changeover switch ui, to the amplifier V.
  • a microphone produces no potential difierence between the distribution point a and ground, and consequently no signal current from the headset H will fiow through the input transformer E of the amplifier. Acoustic reaction between the transducer LM and the head-set H is thereby prevented.
  • an electro-acoustic circuit With a transducer, an amplifier having an input and an output, a telephone receiver having a winding, a. transformer for coupling the transducer circuit to an outside line and switching means connecting the transducer alternately to the input of said amplifier for transmission and to the output for reception of a signal, of a balance circuit, means including said switching means connecting the input of the amplifier with 4 said transformer when said switching means is in position for reception of a signal by the transducer, and means including said'switching means connecting the output of said amplifier with the midpoint of the winding of said receiver when said switching means is in position for transmission of a signal by the transducer, one end of said winding being connected with one terminal of one of the windings of said transformer and the other end being connected through said balance circuit with the other terminal of said transformer winding, the impedance of said balance circuit being substantially identical with the effective impedance of said transformer winding whereby output current from the amplifier is divided substantially equally between the two halves of the winding of the telephone
  • a circuit as claimed in claim 1, in which the means for connecting the input of the amplifier with the transformer comprises a connection between the input of the amplifier and the midpoint of said telephone receiver winding.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)
US573691A 1943-11-03 1945-01-20 Receiver connection in electroacoustic duplex system Expired - Lifetime US2461945A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH2461945X 1943-11-03

Publications (1)

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US2461945A true US2461945A (en) 1949-02-15

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US573691A Expired - Lifetime US2461945A (en) 1943-11-03 1945-01-20 Receiver connection in electroacoustic duplex system

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US (1) US2461945A (de)
CH (1) CH251257A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2559778A (en) * 1948-04-02 1951-07-10 Modern Telephone Corp Intercommunication telephone system
US2577806A (en) * 1945-07-09 1951-12-11 Richard C Lindberg Network for intercommunication system
US3364309A (en) * 1963-06-22 1968-01-16 Int Standard Electric Corp Conference call circuits
US3524936A (en) * 1964-11-10 1970-08-18 World Wide Electronics Inc Automatic telephone answering device having remote control and conference call capability

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1773776A (en) * 1928-03-02 1930-08-26 American Telephone & Telegraph Telephone conference arrangement
US1975932A (en) * 1933-01-09 1934-10-09 Albert L Mcafee Sound-receiving and transmitting system
US2030987A (en) * 1933-08-29 1936-02-18 American Telephone & Telegraph Oscillation control device
US2044305A (en) * 1935-07-01 1936-06-16 Turner Company Communication system
US2199220A (en) * 1939-07-18 1940-04-30 French Hubert Interstation communication system
US2205142A (en) * 1937-02-03 1940-06-18 Holtzer Cabot Electric Co Loudspeaking telephone system
US2214804A (en) * 1939-07-18 1940-09-17 Bell Telephone Labor Inc Two-way communication system
US2282405A (en) * 1939-08-14 1942-05-12 Associated Electric Lab Inc Transmission system

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1773776A (en) * 1928-03-02 1930-08-26 American Telephone & Telegraph Telephone conference arrangement
US1975932A (en) * 1933-01-09 1934-10-09 Albert L Mcafee Sound-receiving and transmitting system
US2030987A (en) * 1933-08-29 1936-02-18 American Telephone & Telegraph Oscillation control device
US2044305A (en) * 1935-07-01 1936-06-16 Turner Company Communication system
US2205142A (en) * 1937-02-03 1940-06-18 Holtzer Cabot Electric Co Loudspeaking telephone system
US2199220A (en) * 1939-07-18 1940-04-30 French Hubert Interstation communication system
US2214804A (en) * 1939-07-18 1940-09-17 Bell Telephone Labor Inc Two-way communication system
US2282405A (en) * 1939-08-14 1942-05-12 Associated Electric Lab Inc Transmission system

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2577806A (en) * 1945-07-09 1951-12-11 Richard C Lindberg Network for intercommunication system
US2559778A (en) * 1948-04-02 1951-07-10 Modern Telephone Corp Intercommunication telephone system
US3364309A (en) * 1963-06-22 1968-01-16 Int Standard Electric Corp Conference call circuits
US3524936A (en) * 1964-11-10 1970-08-18 World Wide Electronics Inc Automatic telephone answering device having remote control and conference call capability

Also Published As

Publication number Publication date
CH251257A (de) 1947-10-15

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