US3617777A - Automatic sensitivity-regulating device - Google Patents

Automatic sensitivity-regulating device Download PDF

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Publication number
US3617777A
US3617777A US887302A US3617777DA US3617777A US 3617777 A US3617777 A US 3617777A US 887302 A US887302 A US 887302A US 3617777D A US3617777D A US 3617777DA US 3617777 A US3617777 A US 3617777A
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Prior art keywords
capacitor
regulating device
amplifier
circuit
transistor
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Expired - Lifetime
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US887302A
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English (en)
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Stefan Kudelski
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/20—Automatic control
    • H03G3/30—Automatic control in amplifiers having semiconductor devices
    • H03G3/3005—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers
    • H03G3/301—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers the gain being continuously variable
    • H03G3/3015—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers the gain being continuously variable using diodes or transistors

Definitions

  • SHEET 10F 3 PATENTEDNnv, 2 1911 mvmmm s'nzwm KUDELSKI I 9W M.
  • This invention relates to a variable impedance, and more particularly, to a variable impedance device providing different recovery time constants.
  • a microphone supplies a signal which is proportional to the acoustic levelwhich it picks up. This level may vary within wide proportions in actual sound recording and to a lesser extent in the case of a telecommunications transmitting microphone.
  • Regulation can be effected manually by means of a potentiometer and a voltmeter which measures the amplitude of the signal or automatically by means of a device which measures the amplitude of the signal and acts on a variable gain device.
  • the known automatic regulators in general comprise a memory which ordinarily consists of a capacitor, the gain being'related to the voltage to which said capacitor is charged.
  • an object of the present invention is to provide automatic sensitivity regulating device which is characterized by the fact that it has two sensitivity recovery time constants, namely, a slow one which is applied permanently in case of the presence of a signal, and the other a rapid one which is placed in operation if the signal remains below a selected level during a selected period of time.
  • Another object of the present invention is to provide an improved automatic sensitivity regulating device.
  • FIG. 1 is a schematic diagram of the present invention
  • FIG. 2 is an explanatory graph therefor
  • FIG. 3 is a schematic diagram of a detail of FIG. 1.
  • an input signal is applied in the form of current to terminals 23, 26, through a series connection of resistor 8 and capacitor 9 to a device 10, the impedance of which varies as a function of a control voltage E which is applied to another input 25 of device 10.
  • the impedance decreases, for instance by 6 db. per 95 v. applied.
  • the signal affected by the variable impedance 10 is supplied to an amplifier ll. phase shifter 12 located at the output of amplifier l 1 comprising a relatively standard capacitor resistor combination enables the signal amplified by amplifier 11 to be provided as two equal signals in phase opposition.
  • the first of these two signals is supplied to the base of transistor T, while the other is applied to the base of transistor T,.
  • Transistors T, and T forma peak rectifier l3 and a capacitor C, connected between their interconnected emitters and a point of reference potential is charged to a voltage, the value of which is related to the peak voltage of the input signal.
  • This voltage on the capacitor C constitutes the control signal E of the variable impedance 10.
  • the capacitor C is discharged by the resistor R, of high value, which causes this discharge to be slow and to last several seconds (slow recovery, for instance I to 2 db. per second on the average).
  • the presence of a signal of sufiicient amplitude is coupled to the base of transistor T through capacitor C, and causes the transistor T to conduct and discharge the capacitor C, which is connected to the collector of transistor T
  • the base of transistor T. is connected to the collector of transistor T and upon the discharge of capacitor C, is rendered nonconductive. If the amplitude of the signal drops below the value necessary to make the transistor '1', conduct, the resistor R connected between the collector of T, to a source of reference potential charges the capacitor C, and, at the end of a period of time t, (FIG. 2), the transistor T starts to conduct and rapidly discharges the capacitor C, through the resistor R (rapid recovery, for instance 10 db. per second).
  • the graph of FIG. 2 illustrates this operation and shows the decrease of the gain at the time of the appearance of the signal, its slow increase during the time t,, and its rapid increase subsequently.
  • the variable impedance device 10 can be developed in the manner shown in FIG. 3.
  • 21 is a diode bridge constituting a variable, nonlinear impedance
  • 22 is a positive source of potential
  • 23 the signal input
  • 24 the signal output
  • 25 the terminal for the application of the control voltage
  • 26 the common ground terminal
  • 27 and 28 the transistors T, and T, respectively
  • 29 a logarithmic circuit.
  • the diagram also shows the currents I, and I the current I the direct current I controlled establishing the operating point and the constant alternating current I What is claimed is:
  • An automatic sensitivity regulating device responsive to the level and duration of an input signal comprising:
  • variable impedance circuit connected to the input circuit for varying the amplitude of the signal applied to the amplifier, said variable impedance including a control terminal, the voltage of which determines the circuit impedance;
  • a capacitor coupled to the amplifier output terminals and to said control terminal, said capacitor chargeable to a DC voltage responsive to the input signal;
  • a second resistor coupled to the capacitor in series with a transistor for discharging the capacitor at a second predetermined rate
  • variable impedance circuit includes a four armed bridge circuit having a diode rectifier in each of its four arms.
  • a regulating device according to claim 2 wherein said bridge circuit is connected to a transistor having base, collector, and emitter electrodes, said collector and emitter electrodes connected in series with the bridge, and the base connected to said control terminal.
  • a regulating device according to claim 1 wherein said amplifier circuit includes output terminals connected to a pair of phase-shifting means with the first of said pair providing a first phase shift and the second of said phase-shifting means providing a second phase shift, said second phase shift being complementary to said first phase shift.
  • a regulating device according to claim I wherein said transistor in series with the second resistor is normally nonconducting and is made conducting by a voltage derived from the output of said amplifier.
  • a regulating device according to claim 1 wherein the output terminals of said amplifier are connected to a full wave rectifier for charging said capacitor.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Amplifiers (AREA)
  • Control Of Amplification And Gain Control (AREA)
US887302A 1968-12-26 1969-12-22 Automatic sensitivity-regulating device Expired - Lifetime US3617777A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH1928968A CH501338A (fr) 1968-12-26 1968-12-26 Compresseur de volume d'un signal électrique

Publications (1)

Publication Number Publication Date
US3617777A true US3617777A (en) 1971-11-02

Family

ID=4438527

Family Applications (1)

Application Number Title Priority Date Filing Date
US887302A Expired - Lifetime US3617777A (en) 1968-12-26 1969-12-22 Automatic sensitivity-regulating device

Country Status (7)

Country Link
US (1) US3617777A (de)
JP (1) JPS504304B1 (de)
AT (1) AT303413B (de)
CH (1) CH501338A (de)
DE (1) DE1965100B2 (de)
FR (1) FR2027131A1 (de)
GB (1) GB1290520A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3735272A (en) * 1971-10-20 1973-05-22 Us Navy Automatic gain control
US3848194A (en) * 1973-07-16 1974-11-12 Matsushita Electric Co Ltd Automatic gain control circuit
US3885168A (en) * 1972-12-26 1975-05-20 Sony Corp Peak detector

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52661B2 (de) * 1972-01-11 1977-01-10
JPS574492Y2 (de) * 1972-05-13 1982-01-27
US4007428A (en) * 1975-08-07 1977-02-08 Danfoss A/S Automatic gain control of pulses
DE2847706C2 (de) * 1978-11-03 1982-08-12 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Schwundregelschaltung für einen Rundfunkempfänger mit Sendersuchlauf, insbesondere für einen Fernsehempfänger
US4424494A (en) * 1981-12-17 1984-01-03 General Motors Corporation Automatic gain control circuit
US4942315A (en) * 1987-06-26 1990-07-17 Tarng Lin J Base point floating cut off wave form differential signal detector circuit

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2719226A (en) * 1951-06-04 1955-09-27 Remington Rand Inc Timed signal generator
US3019396A (en) * 1959-10-09 1962-01-30 Mohawk Business Machines Corp Automatic volume control transistor circuit arrangement
US3068367A (en) * 1959-09-08 1962-12-11 Burroughs Corp Pulse train gap detector circuitry
US3119970A (en) * 1960-03-07 1964-01-28 Northern Electric Co Variable gain amplifiers
US3202929A (en) * 1961-10-30 1965-08-24 Northern Electric Co Semiconductor vario-losser circuit
US3284713A (en) * 1963-03-26 1966-11-08 Motorola Inc Emitter coupled high frequency amplifier

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2719226A (en) * 1951-06-04 1955-09-27 Remington Rand Inc Timed signal generator
US3068367A (en) * 1959-09-08 1962-12-11 Burroughs Corp Pulse train gap detector circuitry
US3019396A (en) * 1959-10-09 1962-01-30 Mohawk Business Machines Corp Automatic volume control transistor circuit arrangement
US3119970A (en) * 1960-03-07 1964-01-28 Northern Electric Co Variable gain amplifiers
US3202929A (en) * 1961-10-30 1965-08-24 Northern Electric Co Semiconductor vario-losser circuit
US3284713A (en) * 1963-03-26 1966-11-08 Motorola Inc Emitter coupled high frequency amplifier

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3735272A (en) * 1971-10-20 1973-05-22 Us Navy Automatic gain control
US3885168A (en) * 1972-12-26 1975-05-20 Sony Corp Peak detector
US3848194A (en) * 1973-07-16 1974-11-12 Matsushita Electric Co Ltd Automatic gain control circuit

Also Published As

Publication number Publication date
DE1965100A1 (de) 1970-07-09
DE1965100B2 (de) 1974-06-12
FR2027131A1 (de) 1970-09-25
CH501338A (fr) 1970-12-31
GB1290520A (de) 1972-09-27
JPS504304B1 (de) 1975-02-18
AT303413B (de) 1972-11-27

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