US2282380A - Feed-back circuit - Google Patents

Feed-back circuit Download PDF

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Publication number
US2282380A
US2282380A US221319A US22131938A US2282380A US 2282380 A US2282380 A US 2282380A US 221319 A US221319 A US 221319A US 22131938 A US22131938 A US 22131938A US 2282380 A US2282380 A US 2282380A
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US
United States
Prior art keywords
supplied
bridge
discharge device
voltage
resistance
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
US221319A
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English (en)
Inventor
Charles S Root
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.)
General Electric Co
Original Assignee
General Electric 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 General Electric Co filed Critical General Electric Co
Priority to US221319A priority Critical patent/US2282380A/en
Priority to NL56049D priority patent/NL56049C/xx
Application granted granted Critical
Publication of US2282380A publication Critical patent/US2282380A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/34—Negative-feedback-circuit arrangements with or without positive feedback
    • H03F1/36—Negative-feedback-circuit arrangements with or without positive feedback in discharge-tube amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D1/00—Demodulation of amplitude-modulated oscillations
    • H03D1/02—Details
    • H03D1/06—Modifications of demodulators to reduce distortion, e.g. by negative feedback
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/02—Manually-operated control
    • H03G3/04—Manually-operated control in untuned amplifiers
    • H03G3/06—Manually-operated control in untuned amplifiers having discharge tubes
    • H03G3/08—Manually-operated control in untuned amplifiers having discharge tubes incorporating negative feedback
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G9/00—Combinations of two or more types of control, e.g. gain control and tone control
    • H03G9/02—Combinations of two or more types of control, e.g. gain control and tone control in untuned amplifiers
    • H03G9/04—Combinations of two or more types of control, e.g. gain control and tone control in untuned amplifiers having discharge tubes
    • H03G9/06—Combinations of two or more types of control, e.g. gain control and tone control in untuned amplifiers having discharge tubes for gain control and tone control
    • H03G9/08—Combinations of two or more types of control, e.g. gain control and tone control in untuned amplifiers having discharge tubes for gain control and tone control incorporating negative feedback

Definitions

  • My invention relates to feed-back circuits for electron discharge devices, and more particularly ent application is assigned, is disclosed an audio amplifier employing a degenerative feed-back system in which the magnitude of the feed-back voltage is automatically reduced upon movement of the manual volume control to increase the ap plication of signal electromotive force to the amplifier.
  • the degeneration is automatically reduced.
  • One of the objects of my invention is to provide certain improvements upon systems of the type described in said Bachman application and more particularly to provide means whereby the feed-back voltage may be reduced to zero upon a certain adjustment of the volume contrql for high sensitivity.
  • a further object of the invention is to provide means whereby the feed-back voltage may be automatically reversed upon movement of the volume control to positions of still higher sensitivity.
  • I have represented therein at l a diode which may be the diode detector of an ordinary, radio receiver. Electromotive forces to be detected by the diode I are supplied thereto by a transformer 2. The detector operates into a load resistance comprising resistors 3 and 4 across which are connected the usual condenser 5. In parallel with the resisters 3 and 4 is a path comprising condenser 8, potentiometer 1 and resistance 8, the variable element 9 of the potentiometer being connected to the grid of an electron discharge device "I.
  • the cathode of this discharge device is connected to a point on the bleeder resistance of the rectiher which supplies operating potential to the discharge devices of the system, this bleeder resistance comprising sections l2, I3, and I4.
  • the anode of discharge device I0 is connected through anode coupling resistor I5 to the bleeder resistance at a point between resistances I3 and I4.
  • Oscillations appearing in the output circuit of the discharge device I!) are supplied through a coupling condenser IE to the control grid of a second electron discharge device H, the output of which is supplied through a transformer Hi to a loud speaker l9.
  • is connected between the cathode of discharge device i1 and ground for bias purposes, the anode thereof being connected through the primary of transformer l8 to the positive side of the source of operating voltage, the negative side of which is grounded as indicated at 22.
  • Conductors 23 one of which includes resistance 24, form a circuit extending from the output of discharge device I! to points respectively upon the two parallel paths, one of which comprises resistances 3 and 4 and the other of which comprises resistances l and 8, the respective points being between these resistances, this circuit com-v prising the feed-back circuit utilized to produce degeneration or regeneration in the system.
  • the two paths 3, 4, and 6, I, and 8 constitute a Wheatstone bridge, the resistances 3 and 4 being the ordinary diode load and having impressed thereon the rectified signal electromotive force, which may be. the ordinary audio voltages produced in the diode circuit of a radio receiver.
  • the resistances in these paths 3, 4, and 6, 1, 8 are so proportioned that these paths comprise a Wheatstone bridge, the two conductors 23 being connected at diagonally opposite corners of the bridge.
  • the cathode of the discharge device I0 is connected through resistance l2 and ground to a third diagonally opposite corner of the bridge which is likewise connected to the cathode of
  • the grid of discharge device I0 is connected to a tap 9 on potentiometer i whereby this connection may be moved along resistance 1.
  • this feedback voltage may be reduced to zero when maximum amplification is required.
  • the point of contact feed-back voltage is supplied to the grid, may be adjusted to a point short of the top of the resistor; that is,
  • the cathode of the audio amplifier comprises the cathode of the audio amplifier plus an additional anode 26. Also the amplifier in this case obtains its bias through the resistor 21 from a suitably negative point 49 of the circuit, which is by-passed by condenser 28. The condenser 39 prevents resistors I and 8 from having any efiect on this bias. The remaining amplifier I have designated on the drawing by a rectangle bearing the legend audio amplifier.” v
  • the diode load comprises a resistance 30, separate and apart from the bridge.
  • the alternating current voltage of this resistance is supplied through coupling condenser 31 to the two parallel paths of the bridge comprising resistances 3, 4, and I, 8.
  • Feed-back conductors 23 are connected to the bridge in the usual way.
  • Resistances 32 and 33 comprise the usual bleeder resistance connected across the usual power supply conductors 35.
  • the resistance 36 operates to maintain the grid of thedischarge device ID at negative potential with respect to its cathode.
  • diode I and discharge device [9 have their cathodes connected to the same point it is obvious that they may be replaced by a single combination diode and amplifier tube having a common cathode.
  • an electron discharge de vice having input electrodes, and an output circuit
  • a Wheatstone bridge means to supply electromotive force to be transmitted through said discharge device to one pair of diagonally opposite corners of said bridge, and means tosupply electromotive force from said output circuit to another pair of diagonally opposite comers of said bridge, the input electrodes of said discharge device being connected between one of said first pair of corners and an arm of said bridge.
  • an electron discharge device having input electrodes, and an output cirsite corners of said bridge, and means to supply The magnitude of resistance 24, of course, de-
  • an electron discharge device having input electrodes, a potentiometer, means to supply signal oscillations across said potentiometer, said input electrodes being variably tapped from said-potentiometer, thereby to vary the portion of said signal oscillations on said potentiometer supplied to said input electrodes, an output circuit, means to supply voltage from said output circuit to said input electrodes to produce degeneration, and means to produce said degeneration when said potentiometer is adjusted at one position and to produce regeneration when said potentiometer is adjusted at another position.
  • an electron discharge de vice having input electrodes, a source of electromotive force to be transmitted through said discharge device, a volume control potentiometer, said input electrodes being connected across a portion of said variable potentiometer to vary the electromotive force of said source supplied to said discharge device, and means to supply voltage from the output circuit to said input circuit in degenerative phase when said input electrodes are connected across a small portion of said potentiometer and in regenerative phase when said input electrodes are connected across a large portion of said potentiometer.
  • a source of electromotive force an electron discharge device having an input electrode connected to one point on said source and another input electrode connected to a point variable along said source to vary the electromotive force applied between said electrodes, an output circuit for said discharge device; means to supply electromotive force from said output circuit between said input electrodes, and means responsive to movement of said variable point along said source to reverse the phase of said electromotive force supplied from said output circuit as applied between said input electrodes.
  • a source of electromotive force two parallel paths connected thereacross, an electron discharge device having an output circuit, a connection between twointermediate points on said paths, input electrodes for said electron discharge device, one of said input electrodes being connected to one side of said source, and the other input electrode being connected to a point movable along the portion of one of said paths adjacent the opposite side of said source, and means to supply voltage to said connection from said output circuit, said voltage being supplied in degenerative phase to one of said points and in regenerative phase to the other of said points.
  • an electron discharge device having an output circuit connected between two intermediate points respectively on said paths, and having input electrodes, one of said input electrodes being connected to one side 01' said source, and the other input electrode being connected to a point movable along the portion of one of said paths adjacent the opposite side of said source whereby the portion of the electromotive force of said source supplied between said electrodes is variable by movement 01 said point along said path, the phase of the voltage supplied from said out put circuit being degenerative as supplied between said electrodes, and said paths being so proportioned that no voltage from the output circuit appears between said electrodes when the point to which said other electrode is connected is such that a large portion of the voltage of said source is supplied to said input circuit.
  • a source of electromotive force two parallel paths connected thereacross
  • an electron discharge device having an output circuit connected between two intermediate points respectively on said paths, and having input electrodes, one of said input electrodes being connected to one side of said source, the other input electrode being connected to a point movable along the portion of one of saidpaths adjacent the opposite side of said source whereby the portion of the electromotive force of said' source supplied between said electrodes is variable by movement of said point along said path, the phase of the voltage supplied from said output circuit being degenerative as supplied between said electrodes, and said paths being so proportioned that no voltage from the output circuit appears between said electrodes when the point to which said other electrode is connected is such that a large portion of the voltage of said source is supplied to said input circuit, and is in regenerative phase when said point is moved to increase the portion of the electromotive force of said source supplied between said electrodes.
  • a diode detector an audio amplifier to amplify signals detected by said diode detector and a Wheatstone bridge con- I said bridge whereby said voltage supplied from said output circuit is impressed on said amplifier input in degenerative phase and is prevented from aflecting said diode by reason of the balance of said bridge.
  • a diode detector an electron discharge amplifier to amplify signals detected by said detector, and having a cathode and input electrode
  • a bridge having two diagonal branches, one of said branches including said diode detector, and the other of said branches including the output of said amplifier, the cathode of said amplifier being connected to the terminus of said one branch adjacent the cathode of said diode and said input electrode being connected to an intermediate point on an arm of said bridge whereby voltage from the output of said amplifier is supplied to said input and is prevented from affecting said diode detector by reason of the balance of said bridge and said ca hodes are at the same potential.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)
US221319A 1938-07-26 1938-07-26 Feed-back circuit Expired - Lifetime US2282380A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US221319A US2282380A (en) 1938-07-26 1938-07-26 Feed-back circuit
NL56049D NL56049C (en)) 1938-07-26 1939-07-25

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US221319A US2282380A (en) 1938-07-26 1938-07-26 Feed-back circuit

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Publication Number Publication Date
US2282380A true US2282380A (en) 1942-05-12

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Application Number Title Priority Date Filing Date
US221319A Expired - Lifetime US2282380A (en) 1938-07-26 1938-07-26 Feed-back circuit

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NL (1) NL56049C (en))

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2876299A (en) * 1956-08-29 1959-03-03 Zenith Radio Corp Signal-translating apparatus
US2905761A (en) * 1956-08-29 1959-09-22 Siegler Corp Control of amplifier source resistance

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2876299A (en) * 1956-08-29 1959-03-03 Zenith Radio Corp Signal-translating apparatus
US2905761A (en) * 1956-08-29 1959-09-22 Siegler Corp Control of amplifier source resistance

Also Published As

Publication number Publication date
NL56049C (en)) 1944-04-15

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