US2496784A - Receiver circuit-arrangement for low-frequency or carrier wave telephony systems - Google Patents

Receiver circuit-arrangement for low-frequency or carrier wave telephony systems Download PDF

Info

Publication number
US2496784A
US2496784A US3964A US396448A US2496784A US 2496784 A US2496784 A US 2496784A US 3964 A US3964 A US 3964A US 396448 A US396448 A US 396448A US 2496784 A US2496784 A US 2496784A
Authority
US
United States
Prior art keywords
circuit
voltage
rectifier
frequency
anode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US3964A
Inventor
Ensink Johannes
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.)
Hartford National Bank and Trust Co
Original Assignee
Hartford National Bank and Trust Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hartford National Bank and Trust Co filed Critical Hartford National Bank and Trust Co
Application granted granted Critical
Publication of US2496784A publication Critical patent/US2496784A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J1/00—Frequency-division multiplex systems
    • H04J1/02—Details
    • H04J1/14—Arrangements providing for calling or supervisory signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q1/00—Details of selecting apparatus or arrangements
    • H04Q1/18—Electrical details
    • H04Q1/30—Signalling arrangements; Manipulation of signalling currents
    • H04Q1/44—Signalling arrangements; Manipulation of signalling currents using alternate current
    • H04Q1/444—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies
    • H04Q1/446—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies using one signalling frequency
    • H04Q1/4465—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies using one signalling frequency the same frequency being used for all signalling information, e.g. A.C. nr.9 system

Definitions

  • the invention relates'to "a receiver circuitarrangement for low fre'quency or: carrier-wave systems for amplifying low-i-freqnenc'y speech currents and for receivingsignalling impulses having a frequency'in the speech frequency band.”
  • the transmitted impulses are consequently built (whom a number 'of' periods of an oscillation, -tne' rrequency or which -is included in the speech -freq-uncy band cry: for example, from 300 to 3000 'c/s and "is, fo'r *example 2500 c/s.
  • Termination of the signalling impulse results .:.in damping of theoscillation'across'the circuit 8, so that the voltage across this circuit is decreased whilst with properly chosen time-constant of the parallel-combination in, II, for example 50 milliseconds the cut-oif voltage subsists for some more time.
  • I4 is chosen to be small, for example 2 msec. so that the voltage occurring across is decreased very rapidly, with the result that the pentode 4- is again ready for amplifying speech current signals.
  • the input circuit of the discharge tube has set up across it a negative bias voltage which is taken from a capacity to which the voltage set up across a resistance included in the cathode lead of the discharge tube is fed through a rectifier which is cut-off on reception of signalling impulses.
  • the negative bias voltage is taken from the capacity I1. This is charged with the aid of the voltage set up across the resistance which is included in the cathode lead and with which a small part I! of the potentiometer connected to the source of supply voltage is connected in series.
  • This generated negative bias voltage has the eifect of substantially obviating any variation in value of the anode current on replacement or change of the discharge tubes.
  • the generated negative bias voltage should preferably not change upon the occurrence of signalling impulses, so that the time-constant of the network used for producing these voltages should exceed the time period of the longest impulse that occurs of the order of 400 msec.
  • control-grid circuit already comprises a comparatively heavy resistance l3.
  • circuit-arrangement shown ensures that in the conductive direction of the rectifier when the latter exhibits an internal resistance of the order of magnitude of 10,000 9 a positive gridcurrent will not occur and in the other direction,
  • said system comprising an electron discharge tube including a cathode, a grid and an anode, means coupled to said grid for applying the audio currents and the si nal pulses thereto, means coupled to said anode for deriving amplified audio currents therefrom, a resonant network coupled to said anode and tuned to the frequency of said signal pulses, a first resistance-capacitance parallel circuit, a first rectifier, means coupling said first circuit through said first rectifier to said anode to charge said first circuit, a second resistancecapacitance parallel circuit, a second rectifier, means connecting said resonant network in series with said first circuit through said second rectifier across said second circuit to charge said second circuit solely when an oscillatory voltage is developed across said resonant network, means to apply the voltage developed across said second circuit to said grid to render said tube non-conductive during the existence of signal pulses, and means coupled
  • a telephone receiving system for selectively amplifying audio currents and intercepting signal pulses formed by oscillations whose frequency lies within the audio range, said system comprising an electron discharge amplifying tube including a cathode, a grid and an anode, an input circuit coupled to said grid for applying the audio currents and the signal pulses thereto, an output circuit coupled to said anode for deriving amplified audio currents therefrom, a resonant network coupled to said output circuit and tuned to the frequency of said signal pulses, a first blocking voltage resistance-capacitance parallel circuit connected in series with said resonant network, a first rectifier, means coupling said first blocking voltage circuit through said first rectifier to said output circuit to charge said first blocking voltage circuit, a second blocking voltage resistance-capacitance parallel circuit, asecond rectifier,means connecting said serially-connected resonant network and said first circuit through said second rectifier across said second blocking voltage circuit to charge said second blocking voltage circuit solely when an oscillatory voltage is developed across said resonant network
  • a telephone receiving system for selectively amplifying audio currents and intercepting signal pulses formed by oscillations whose frequency lies within the audio range, said system comprising an electron discharge tube including a cathode, a grid and an anode, an input circuit coupled to said grid, means to apply said audio currents and said signal pulses to said input circuit, an output circuit coupled to said anode, a signal relay having an energizing winding, first and second coupling transformers each having a primary and a secondary, means to apply an anode potential through said output circuit in series with said relay winding and the primaries of said first and-second coupling transformers to said anode whereby said relay is energized during the conduction of said tube, a condenser connected in parallel with the secondary of said first transformer to define therewith a resonant network tuned to the frequency of said signal pulses, a first resistance-capacitance parallel circuit, a first rectifier connected in series with said first circuit across the secondary of said second coupling transformer, said first circuit and said
  • a telephone receiving system for selectively amplifying audio currents and intercepting signal pulses formed by oscillations whose frequency lies within the audio range, said system comprising an electron discharge amplifying tube including a cathode, a grid and an anode, an input transformer having a primary and a secondary one end of which is connected to said grid, means to apply said audio currents and said signal pulses to the primary of said input transformer, an output transformer having a primary one end of which is connected to said anode and a secondary, a signal relay having an energizing winding, first and second coupling transformers each having a primary and a secondary, means to apply an anode potential to the other end of the primary of said output transformer through said relay winding in series with the primaries of said first and second.
  • a telephone receiving system for selectively amplifying audio currents and intercepting signal pulses formed by oscillations whose frequency lies within the audio range, said system comprising an electron discharge amplifying tube including a cathode, a grid and an anode, an input transformer having a primary and a secondary, one end of which is connected to said grid, means to apply said audio currents and said signal pulses to the primary of said input transformer, an output transformer having a primary one end of which is connected to said anode and a secondary, a signal relay having an energizing winding, first and second coupling transformers each having a primary and a secondary, a source of anode potential having the positive terminal thereof connected to the other end of the primary of said output transformer through said relay winding in series with the primaries of said first and second coupling transformers whereby said relay is energized during the conduction of said tube, a condenser connected in parallel with the secondary of said first transformer to define therewith a resonant network tuned to the frequency of said signal pulses

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Devices For Supply Of Signal Current (AREA)
  • Telephonic Communication Services (AREA)

Description

' Feb. 7, 1950 J. ENSINK 2,496,784
RECEIVER CIRCUIT-ARRANGEMENT FOR LOW-FREQUENCY 0R CARRIER WAVE TELEPHONY SYSTEMS Filed Jan. 2a, 1948 JOHANNESENSJNK.
E INVENTOR.
BY%M
AGEZVI.
Patented F eb. 7,1950
UN IT EiD ,"PATENT OFFICE 2,496,784 RECEIVE JI UI ARRANGEMENT FOR LOWgEREQUENCY R CARRIER WAVE. "TELEPHONY :sYs'rEMs Johannes f; Ensink, Eindhoven, Netherlands, "as- -.=signor.'to-Hartf0rd National Bank and Trust Company,"Hartford, Conn., as trustee Al plicati'ondanuary 23,1948, Serial No. 3,964
ln -theNetherlands February 21, 1947 0 As is well-known;in=telephonyzsystems not-only speech currents, which maybe-understoodtoinclude music, but also dialling and calling signals and the like 'arerequiredto- :be transmitted.
At the transmittrend these" 1 signals have the character of direct current impulses, but incarrier-wave telephony systems and also in lowfrequency systems, *in' which transmission is effected through pupini'sedTcables, are converted into alternating current-impulses, teach impulse being built up from a' numbernf periods 0f a lowfrequency 'or high-frequency "oscillation, then they are transmitted. Attheirec'eiverend these impulses must "bore-"converted intodirect current impulses.
The invention relates'to "a receiver circuitarrangement for low fre'quency or: carrier-wave systems for amplifying low-i-freqnenc'y speech currents and for receivingsignalling impulses having a frequency'in the speech frequency band."
In the present case the transmitted impulses are consequently built (whom a number 'of' periods of an oscillation, -tne' rrequency or which -is included in the speech -freq-uncy band cry: for example, from 300 to 3000 'c/s and "is, fo'r *example 2500 c/s.
These signal-ling impulses inust *therefore- *be separated at the receiver end froin speech cun rents to Wit in such 'manner "asto prevent signalling impulses 'from inducing "interference "in the transmitted conversation and, on'the "other hand, oscillations of 2500 c/s in thes'pee'ch currents from inducin'g interference in-signalling.
- In an arrangement acc'ording to the invention, the incoming'signalis fedto theinput circuitof a discharge tube,'from=' the output circuitof-vvhich the speech currents'are abstractedpthis output circuit has coupled to it'a circuit tuned to the frequency of the-signalling' impulsesand a circuit including a rectifier'and connected in series therewith aparallel combination of a resistance and a capacity, the 'voltagesset rip-across the tuned circuit and across the parallel-combination being combined in such ma'n'ne'r and being supplied in such manner to' a'seco'n'd rectifier'with l which is connected 'in's'eriesase'cond parallel 'com- *bination of a resista'nce- 'a'nd acapa'clty, which combination is included in the; input circuit of the discharge tube, that on reception-of signalling'impuls'es a relay whi'ch-controls a signal current circuit and which -is included in the 'outut circuit of the tubepec'omes iipei-ative.
In order that the invention ma be -m'ore "clearly understoodand readily carriedi-into effect, itwill now be described nioresfu-llywith reference' to the alternative, may becombined 'to form a' single transformer comprising one primary and two secondary windings, the-output circuit of the pentode 4 hasin addition-coupledto it-the-cir- -cuit 8 tuned toithe-singalling impulses, for example to 2500 c/s, and the rectifier circuit 9.
Upon supply of asignalling impulse to the input terminals I, '2,'a'high alternatingvoltage'is set up across the circuit 8 and a direct voltage having a polarity as shown in the drawing is set up across the parallel-combination of resistance I0 and capacity l I.
These voltages are combined and supplied through rectifier l2 to'the parallel-combination of resistance l3 and capacity l4 includedin the input circuit, the voltage across the parallelcombination l0, ll having a blocking "efiect on the rectifier l2 so that the latter only allows current to pass, if a signalling impulse is fed' to the input'terminals l,'2 with the result that the circuit 8 has set up across it a voltage which exceeds the blocking voltage. Supply of voltages of speech currents having'a frequency different from 2500 0/5 results in a blocking voltage and'if 'oc casionally a speech-current frequency of 2500 "MS cccurs, the'condenser=lI is charged comparatively rapidly byway of the'small re'sistanceof the rectifier and the voltage across the tuned circuit has not yet been exhausted to the required higher voltage.
On reception of 'a'signalling impulse the parallel-combination l3, M'has setup across it a voltage of the polarity indicated in the drawing. Consequently. the discharge tubeis substantially cut off, owing to which'the direct current in the output circuit is decreased to 'the' extent-of the signalling relay i5 inclu'dedin this circuit "and controlling the signal-current circuit being deenergized and this enables a 'direct current impulse to be set up in the said signal current circuit.
Termination of the signalling impulse results .:.in damping of theoscillation'across'the circuit 8, so that the voltage across this circuit is decreased whilst with properly chosen time-constant of the parallel-combination in, II, for example 50 milliseconds the cut-oif voltage subsists for some more time. In contradistinction to this the time-constant of the parallel-combination 3, I4 is chosen to be small, for example 2 msec. so that the voltage occurring across is decreased very rapidly, with the result that the pentode 4- is again ready for amplifying speech current signals.
In a favourable form of the circuit-arrangement according to the invention the input circuit of the discharge tube has set up across it a negative bias voltage which is taken from a capacity to which the voltage set up across a resistance included in the cathode lead of the discharge tube is fed through a rectifier which is cut-off on reception of signalling impulses.
The negative bias voltage is taken from the capacity I1. This is charged with the aid of the voltage set up across the resistance which is included in the cathode lead and with which a small part I! of the potentiometer connected to the source of supply voltage is connected in series.
As long as signalling impulses do not occur, there is set up by the anode-direct anode current of the tube 4 across the resistance IS a voltage drop which exceeds the voltage across the resistance l9, which voltage has a blocking effect. The capacity I! is then charged by way of the rectifier 20. On reception of signalling impulses at which the direct anode current is very small, the rectifier is blocked.
This generated negative bias voltage has the eifect of substantially obviating any variation in value of the anode current on replacement or change of the discharge tubes.
It is well to note that the generated negative bias voltage should preferably not change upon the occurrence of signalling impulses, so that the time-constant of the network used for producing these voltages should exceed the time period of the longest impulse that occurs of the order of 400 msec.
In this case the usual parallel-combination of resistance and capacity cannot be used, since this requires either a high capacity value, which is undesirable in view of the space available in telephony receivers, or involves the use of a high resistance value.
The latter requirement is also undesirable, since the secondary electron-emission which is always evolved by the control-grid may have the effect of setting up a positive control-grid voltage, whilst the control-grid circuit already comprises a comparatively heavy resistance l3.
Thus the circuit-arrangement shown ensures that in the conductive direction of the rectifier when the latter exhibits an internal resistance of the order of magnitude of 10,000 9 a positive gridcurrent will not occur and in the other direction,
- when the internal resistance is of the order of nal pulses formed by oscillations whose frequency lies within the audio range, said system comprising an electron discharge tube including a cathode, a grid and an anode, means coupled to said grid for applying the audio currents and the si nal pulses thereto, means coupled to said anode for deriving amplified audio currents therefrom, a resonant network coupled to said anode and tuned to the frequency of said signal pulses, a first resistance-capacitance parallel circuit, a first rectifier, means coupling said first circuit through said first rectifier to said anode to charge said first circuit, a second resistancecapacitance parallel circuit, a second rectifier, means connecting said resonant network in series with said first circuit through said second rectifier across said second circuit to charge said second circuit solely when an oscillatory voltage is developed across said resonant network, means to apply the voltage developed across said second circuit to said grid to render said tube non-conductive during the existence of signal pulses, and means coupled to said anode and responsive to the non-conduction of said tube to produce output signal impulses in accordance with said input signal pulses.
2. A telephone receiving system for selectively amplifying audio currents and intercepting signal pulses formed by oscillations whose frequency lies within the audio range, said system comprising an electron discharge amplifying tube including a cathode, a grid and an anode, an input circuit coupled to said grid for applying the audio currents and the signal pulses thereto, an output circuit coupled to said anode for deriving amplified audio currents therefrom, a resonant network coupled to said output circuit and tuned to the frequency of said signal pulses, a first blocking voltage resistance-capacitance parallel circuit connected in series with said resonant network, a first rectifier, means coupling said first blocking voltage circuit through said first rectifier to said output circuit to charge said first blocking voltage circuit, a second blocking voltage resistance-capacitance parallel circuit, asecond rectifier,means connecting said serially-connected resonant network and said first circuit through said second rectifier across said second blocking voltage circuit to charge said second blocking voltage circuit solely when an oscillatory voltage is developed across said resonant network, means to apply the voltage developed across said second blocking voltage circuit to said input circuit to render said tube non-conductive during the existence of signal pulses, and means coupled to said output circuit and responsive to the non-conduction of said tube to produce output signal impulses in accordance with said input signal pulses.
3. A telephone receiving system for selectively amplifying audio currents and intercepting signal pulses formed by oscillations whose frequency lies within the audio range, said system comprising an electron discharge tube including a cathode, a grid and an anode, an input circuit coupled to said grid, means to apply said audio currents and said signal pulses to said input circuit, an output circuit coupled to said anode, a signal relay having an energizing winding, first and second coupling transformers each having a primary and a secondary, means to apply an anode potential through said output circuit in series with said relay winding and the primaries of said first and-second coupling transformers to said anode whereby said relay is energized during the conduction of said tube, a condenser connected in parallel with the secondary of said first transformer to define therewith a resonant network tuned to the frequency of said signal pulses, a first resistance-capacitance parallel circuit, a first rectifier connected in series with said first circuit across the secondary of said second coupling transformer, said first circuit and said resonant circuit being connected in series, a second resistance-capacitance parallel circuit, a sec ond rectifier, and means to connect said seriallyconnected resonant network and said first circuit through said second rectifier across said second circuit, said first circuit applying a bias across said second rectifier which is overcome by the oscillatory voltage developed across said resonant network solely during the existence of signal pulses to charge said second circuit, and means to apply the voltage developed across said second circuit to said input circuit to render said tube non-conductive during the existence of signal pulses, thereby to deenergize said relay.
4. A telephone receiving system for selectively amplifying audio currents and intercepting signal pulses formed by oscillations whose frequency lies within the audio range, said system comprising an electron discharge amplifying tube including a cathode, a grid and an anode, an input transformer having a primary and a secondary one end of which is connected to said grid, means to apply said audio currents and said signal pulses to the primary of said input transformer, an output transformer having a primary one end of which is connected to said anode and a secondary, a signal relay having an energizing winding, first and second coupling transformers each having a primary and a secondary, means to apply an anode potential to the other end of the primary of said output transformer through said relay winding in series with the primaries of said first and second. coupling transformers whereby said relay is energized during the conduction of said tube, a condenser connected in parallel with the secondary of said first transformer to define therewith a resonant network tuned to the frequency of said signal pulses, a first blocking voltage resistance-capacitance parallel circuit, a first rectifier connected in series with said blocking voltage circuit across the secondary of said second coupling transformer, said first blocking voltage circuit and said resonant circuit being connected in series, a second blocking voltage resistance-capacitance parallel circuit having one terminal thereof connected to .the other end of the secondary of said input transformer and the other terminal thereof coupled to said cathode, a second rectifier, and means to connect said serially-connected resonant network and first blocking voltage circuit through said second rectifier across said second blocking voltage circuit, said first blocking voltage circuit applying a bias across said second rectifier which is overcome by the oscillatory voltage developed across said resonant network solely during the existence of signal pulses to charge said second blocking voltage circuit thereby to apply a cut-off bias to said tube and deenergize said relay in the anode circuit thereof.
5. A telephone receiving system for selectively amplifying audio currents and intercepting signal pulses formed by oscillations whose frequency lies within the audio range, said system comprising an electron discharge amplifying tube including a cathode, a grid and an anode, an input transformer having a primary and a secondary, one end of which is connected to said grid, means to apply said audio currents and said signal pulses to the primary of said input transformer, an output transformer having a primary one end of which is connected to said anode and a secondary, a signal relay having an energizing winding, first and second coupling transformers each having a primary and a secondary, a source of anode potential having the positive terminal thereof connected to the other end of the primary of said output transformer through said relay winding in series with the primaries of said first and second coupling transformers whereby said relay is energized during the conduction of said tube, a condenser connected in parallel with the secondary of said first transformer to define therewith a resonant network tuned to the frequency of said signal pulses, a first blocking Voltage resistance-capacitance parallel circuit, a first rectifier connected in series with said blocking voltage circuit across the secondary of said second coupling transformer, said first blocking voltage circuit and said resonant circuit being connected in series, a second blocking voltage resistancecapacitance parallel circuit having one terminal thereof connected to the other end of the secondary of said input transformer, a capacitor connecting the other terminal of said second circuit to said cathode, a second rectifier, means to connect said serially-connected resonant network and first blocking voltage circuit through said second rectifier across said second blocking voltage circuit, said first blocking voltage circuit applying a bias across said second rectifier which is overcome by the oscillatory voltage developed across said resonant network solely during the existence of signal pulses to charge said second blocking voltage circuit thereby to apply a cutoff bias to said tube and deenergize said relay, a resistor connected between the negative terminal of said source and said cathode, and a third rectifier connected between said other terminal of said second blocking network and an intermediate point in said source, the voltage developed.
across said resistor during the conduction of said tube to charge said capacitor through said third rectifier being cut off on reception of signal pulses.
JOHANNES ENSINK.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,958,166 Laurent May 8, 1934 2,018,464 Nibel Oct. 22, 1935 2,145,053 Meszar M Jan. 24, 1939 2,164,185 Bertnolli June 27, 1939 2,199,179 Koch Apr. 30, 1940 2,251,958 Skillman Aug. 12, 1941 2,265,203 Six Dec. 9, 1941 2,282,405 Herrick May 12, 1942 2,319,306 Dickieson May 18, 1943 2,366,011 Donaldson Dec. 26, 1944
US3964A 1947-02-21 1948-01-23 Receiver circuit-arrangement for low-frequency or carrier wave telephony systems Expired - Lifetime US2496784A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL130519 1947-02-21

Publications (1)

Publication Number Publication Date
US2496784A true US2496784A (en) 1950-02-07

Family

ID=19750410

Family Applications (1)

Application Number Title Priority Date Filing Date
US3964A Expired - Lifetime US2496784A (en) 1947-02-21 1948-01-23 Receiver circuit-arrangement for low-frequency or carrier wave telephony systems

Country Status (6)

Country Link
US (1) US2496784A (en)
CH (1) CH265981A (en)
DE (1) DE841924C (en)
FR (2) FR961481A (en)
GB (1) GB656189A (en)
NL (1) NL69785C (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE903824C (en) * 1950-06-15 1954-02-11 Mix & Genest Ag Electrical signal receivers, in particular audio frequency signal receivers
DE931711C (en) * 1950-08-27 1955-08-16 Lorenz C Ag Receiver for alternating current pulses
US2920144A (en) * 1952-04-09 1960-01-05 Philips Corp Circuit arrangement responsive to dialling signals and the like

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE973493C (en) * 1950-09-28 1960-03-10 Philips Nv Single sideband carrier frequency telephone system
DE939820C (en) * 1952-05-06 1956-03-01 Siemens Ag Circuit arrangement for receiving voltages of one or more signal frequencies
FI104995B (en) 1999-01-28 2000-05-15 Halton Oy Control structure of valve for controlling gaseous media such as airflow

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1958166A (en) * 1927-01-04 1934-05-08 Ericsson Telefon Ab L M Electrical signal receiver
US2018464A (en) * 1930-06-07 1935-10-22 Bell Telephone Labor Inc Voice operated transmission circuit
US2145053A (en) * 1936-11-18 1939-01-24 Bell Telephone Labor Inc Signaling system
US2164185A (en) * 1937-05-22 1939-06-27 Great Lakes Pipe Line Company Voice operated repeater
US2199179A (en) * 1936-11-27 1940-04-30 Rca Corp Single channel two-way communication system
US2251958A (en) * 1937-01-29 1941-08-12 Hartford Nat Bank & Trust Co Telephony
US2265203A (en) * 1938-05-16 1941-12-09 Hartford Nat Bank & Trust Co Telephony
US2282405A (en) * 1939-08-14 1942-05-12 Associated Electric Lab Inc Transmission system
US2319306A (en) * 1941-10-31 1943-05-18 Bell Telephone Labor Inc Signaling system
US2366011A (en) * 1941-07-23 1944-12-26 Kellogg Switchboard & Supply Two-way amplifier

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR812623A (en) * 1936-01-16 1937-05-13 Applic Telephoniques Soc D Device for reception and retransmission of signals over long distance telephone lines
GB495162A (en) * 1938-02-22 1938-11-08 Arthur Reginald Albert Rendall Improvements in and relating to alternating current signalling systems

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1958166A (en) * 1927-01-04 1934-05-08 Ericsson Telefon Ab L M Electrical signal receiver
US2018464A (en) * 1930-06-07 1935-10-22 Bell Telephone Labor Inc Voice operated transmission circuit
US2145053A (en) * 1936-11-18 1939-01-24 Bell Telephone Labor Inc Signaling system
US2199179A (en) * 1936-11-27 1940-04-30 Rca Corp Single channel two-way communication system
US2251958A (en) * 1937-01-29 1941-08-12 Hartford Nat Bank & Trust Co Telephony
US2164185A (en) * 1937-05-22 1939-06-27 Great Lakes Pipe Line Company Voice operated repeater
US2265203A (en) * 1938-05-16 1941-12-09 Hartford Nat Bank & Trust Co Telephony
US2282405A (en) * 1939-08-14 1942-05-12 Associated Electric Lab Inc Transmission system
US2366011A (en) * 1941-07-23 1944-12-26 Kellogg Switchboard & Supply Two-way amplifier
US2319306A (en) * 1941-10-31 1943-05-18 Bell Telephone Labor Inc Signaling system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE903824C (en) * 1950-06-15 1954-02-11 Mix & Genest Ag Electrical signal receivers, in particular audio frequency signal receivers
DE931711C (en) * 1950-08-27 1955-08-16 Lorenz C Ag Receiver for alternating current pulses
US2920144A (en) * 1952-04-09 1960-01-05 Philips Corp Circuit arrangement responsive to dialling signals and the like

Also Published As

Publication number Publication date
FR963277A (en) 1950-07-05
GB656189A (en) 1951-08-15
DE841924C (en) 1952-06-19
FR961481A (en) 1950-05-12
CH265981A (en) 1949-12-31
NL69785C (en)

Similar Documents

Publication Publication Date Title
US2564017A (en) Clamp circuit
US2496784A (en) Receiver circuit-arrangement for low-frequency or carrier wave telephony systems
US2240281A (en) Automatic background control
US1477017A (en) Current-controlling and static-reducing system
US2085402A (en) Method of and apparatus for producing electrical waves
US2611081A (en) Automatic gain control system
US2207389A (en) Cathode ray tube deflecting circuit
US2215482A (en) Carrier wave telephony
US3306981A (en) Coding and receiving circuits for compatible stereophonic broadcast systems
US2208398A (en) Radio receiver
US2343753A (en) Receiving circuit for telegraph signaling systems
US2806903A (en) Voice frequency signal receivers
US1932679A (en) Electrical signaling system
US2465782A (en) Frequency modulation receiver
US2598996A (en) Electric carrier wave signaling system
US2144921A (en) Automatic volume control
US2389919A (en) Augmented automatic gain control
US2114332A (en) Keying
US2938081A (en) Selective transmission system for telephonic ringing
US2326457A (en) Alternating current signaling system
US2657280A (en) Hydbrid circuits
US1976096A (en) Electrical signaling system
US2163217A (en) Television receiver circuit
US2646532A (en) System for generating a periodic scanning current
US2803746A (en) Automatic radio receiver selector