US3665332A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Avc system
Assignee: Webster Electric Co Inc
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Filing: 1970-04-20
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Granted: 1972-05-23
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Expires: 1990-04-20
Abstract
Abstract An audio amplifier is provided with an automatic volume control system including an unpolarized junction transistor coupled in shunt with the amplifier input terminals and serving as a bidirectional variable resistance shunt having a resistance level controlled in accordance with an AVC operating signal appearing upon a capacitor charged by a detecting circuit in accordance with the amplifier output signal amplitude. Release time of the AVC system is determined by a variable resistance device connected in a capacitor discharge path, and the device is controlled to have decreasing resistance as amplifier output signals decrease. Sensitivity of the amplifier is controlled by an adjustable circuit providing a residual, nonvarying signal component to the control electrode of the unpolarized transistor to establish a maximum resistance level.
Inventors
- 👤 Richard H Campbell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 07:23
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/3005; H03G3/301; H03G3/3015
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
385 words
An AVC system for use with an amplifier having a pair of input terminals through which are received input signals for the amplifier and a pair of output terminals through wHich output signals are supplied to a signal utilization device, said system comprising: detecting circuit means coupled to the amplifier output terminals for developing an AVC operating potential substantially in accordance with the magnitude of said output signals, said detecting circuit means including rectifier means coupled to said output terminals for providing a DC voltage having a value determined by the magnitude of the output signals and a control capacitor coupled to said rectifier means; a variable resistance device connected in shunt with the amplifier input terminals, and comprising a first transistor having a first control electrode and having first and second output electrodes, said first output electrode being coupled to one of said input terminals and said second output electrode being coupled to the outer of said input terminals; unpolarizing means for preventing the application of a polarizing DC potential to said first output electrode; coupling means coupling the first control electrode of said first transistor to said detecting circuit means for operation of the first transistor at a resistance level determined by said AVC operating potential, said coupling means including a second transistor having a second control electrode coupled to said detecting circuit means for receiving said AVC operating potential from said detecting circuit means and third and fourth output electrodes one of which said third and fourth output electrodes being coupled to said first control electrode so that said second transistor controls the resistance level of said first transistor; and a discharge path for said control capacitor to discharge said control capacitor following the termination of amplifier output signals above a predetermined magnitude, said discharge path including a third transistor and circuit means connected between the amplifier output terminals and said third transistor for decreasing the resistance of said third transistor in response to the decreasing of the magnitude of said output signals below the predetermined magnitude, said circuit means including additional rectifying means for providing a DC signal substantially proportional to the amplifier output signal and a fourth transistor having a third control electrode coupled to said additional rectifying means and having a fifth output electrode coupled to said third transistor.
Claim 2
Dependent Claim
385 words
An AVC system for use with an amplifier having a pair of input terminals through which are received input signals for the amplifier and a pair of output terminals through wHich output signals are supplied to a signal utilization device, said system comprising: detecting circuit means coupled to the amplifier output terminals for developing an AVC operating potential substantially in accordance with the magnitude of said output signals, said detecting circuit means including rectifier means coupled to said output terminals for providing a DC voltage having a value determined by the magnitude of the output signals and a control capacitor coupled to said rectifier means; a variable resistance device connected in shunt with the amplifier input terminals, and comprising a first transistor having a first control electrode and having first and second output electrodes, said first output electrode being coupled to one of said input terminals and said second output electrode being coupled to the outer of said input terminals; unpolarizing means for preventing the application of a polarizing DC potential to said first output electrode; coupling means coupling the first control electrode of said first transistor to said detecting circuit means for operation of the first transistor at a resistance level determined by said AVC operating potential, said coupling means including a second transistor having a second control electrode coupled to said detecting circuit means for receiving said AVC operating potential from said detecting circuit means and third and fourth output electrodes one of which said third and fourth output electrodes being coupled to said first control electrode so that said second transistor controls the resistance level of said first transistor; and a discharge path for said control capacitor to discharge said control capacitor following the termination of amplifier output signals above a predetermined magnitude, said discharge path including a third transistor and circuit means connected between the amplifier output terminals and said third transistor for decreasing the resistance of said third transistor in response to the decreasing of the magnitude of said output signals below the predetermined magnitude, said circuit means including additional rectifying means for providing a DC signal substantially proportional to the amplifier output signal and a fourth transistor having a third control electrode coupled to said additional rectifying means and having a fifth output electrode coupled to said third transistor.
Claim 3
Dependent Claim
35 words
The AVC system of claim 1 wherein said circuit means further includes manually adjustable means coupled to said third control electrode of said fourth transistor for selectively varying the release time of said AVC system.
Claim 4
Dependent Claim
24 words
The AVC system of claim 1, said detecting circuit means further comprising a transformer coupled between said amplifier output terminals and said rectifier means.
Claim 5
Dependent Claim
23 words
The AVC system of claim 3, said rectifier means comprising full-wave rectifier means, and said control capacitor having a relatively small capacitance value.
Claim 6
Dependent Claim
271 words
An AVC system for use with an amplifier having a pair of input terminals through which are received input signals for the amplifier and a pair of output terminals through which output signals are supplied to a signal utilization device, said system comprising: detecting circuit means coupled to the amplifier output terminals for developing an AVC operating potential substantially in accordance with the magnitude of said output signals; a variable resistance device connected in shunt with the amplifier input terminals, and comprising a first transistor having a first control electrode and having first and second output electrodes, said first output electrode being coupled to one of said input terminals and said second output electrode being coupled to the other of said input terminals; unpolarizing means for preventing the application of a polarizing DC potential to said first output electrode; coupling means coupling the first control electrode of said first transistor to said detecting circuit meanS for operation of the first transistor at a resistance level determined by said AVC operating potential, said coupling means including a second transistor having a second control electrode coupled to said detecting circuit means for receiving said AVC operating potential from said detecting circuit means and third and fourth output electrodes one of which said third and fourth output electrodes being coupled to said first control electrode so that said second transistor controls the resistance level of said first transistor; and a sensitivity control coupled to said second transistor to control the maximum resistance level of said first transistor and comprising a source of DC potential coupled to said second control electrode through a variable resistor.
Claim 7
Dependent Claim
271 words
An AVC system for use with an amplifier having a pair of input terminals through which are received input signals for the amplifier and a pair of output terminals through which output signals are supplied to a signal utilization device, said system comprising: detecting circuit means coupled to the amplifier output terminals for developing an AVC operating potential substantially in accordance with the magnitude of said output signals; a variable resistance device connected in shunt with the amplifier input terminals, and comprising a first transistor having a first control electrode and having first and second output electrodes, said first output electrode being coupled to one of said input terminals and said second output electrode being coupled to the other of said input terminals; unpolarizing means for preventing the application of a polarizing DC potential to said first output electrode; coupling means coupling the first control electrode of said first transistor to said detecting circuit meanS for operation of the first transistor at a resistance level determined by said AVC operating potential, said coupling means including a second transistor having a second control electrode coupled to said detecting circuit means for receiving said AVC operating potential from said detecting circuit means and third and fourth output electrodes one of which said third and fourth output electrodes being coupled to said first control electrode so that said second transistor controls the resistance level of said first transistor; and a sensitivity control coupled to said second transistor to control the maximum resistance level of said first transistor and comprising a source of DC potential coupled to said second control electrode through a variable resistor.
Claim 8
Dependent Claim
49 words
The AVC system of claim 5, said unpolarizing preventing means comprising first and second capacitors, said first capacitor being coupled between said first output electrode and said one input terminal and said second capacitor being coupled between said first output electrode and a first amplifier stage of said amplifier.
Claim 9
Dependent Claim
14 words
The AVC system of claim 5, said first transistor comprising a silicon junction transistor.
Claim 10
Dependent Claim
172 words
An amplifier AVC system for use with an amplifier having an amplifier output to supply amplifier output signals, said system comprising in combination; a capacitor a control means coupled between the capacitor and the amplifier for exercising a control function with respect to the amplifier in accordance with the voltage across the capacitor; means including a discharge transistor having first and second output electrodes and a first control electrode, said first and second output electrodes coupled across the capacitor to form a capacitor discharge circuit; first rectifier means coupled between the amplifier output and the capacitor for charging the capacitor upon an increase in amplifier output signal magnitude; a control transistor having third and fourth output electrodes and a second control electrode, said third output electrode being coupled to said first control electrode of said discharge transistor; and second rectifier means coupled between the amplifier output and said second control electrode of said control transistor for decreasing the resistance of said capacitor discharge circuit upon a decrease in amplifier output signal magnitude.
Claim 11
Dependent Claim
172 words
An amplifier AVC system for use with an amplifier having an amplifier output to supply amplifier output signals, said system comprising in combination; a capacitor a control means coupled between the capacitor and the amplifier for exercising a control function with respect to the amplifier in accordance with the voltage across the capacitor; means including a discharge transistor having first and second output electrodes and a first control electrode, said first and second output electrodes coupled across the capacitor to form a capacitor discharge circuit; first rectifier means coupled between the amplifier output and the capacitor for charging the capacitor upon an increase in amplifier output signal magnitude; a control transistor having third and fourth output electrodes and a second control electrode, said third output electrode being coupled to said first control electrode of said discharge transistor; and second rectifier means coupled between the amplifier output and said second control electrode of said control transistor for decreasing the resistance of said capacitor discharge circuit upon a decrease in amplifier output signal magnitude.
Claim 12
Dependent Claim
31 words
The AVC system of claim 8, further comprising manually adjustable means coupled to said second control electrode of said control transistor for selectively varying the release time of said AVC system.
Claim 13
Dependent Claim
33 words
The AVC system of claim 9 wherein said manually adjustable means is a plurality of delay capacitors any one of which is connectable between said second rectifier means and said second control electrode.
Claim 14
Dependent Claim
30 words
The amplifier AVC system of claim 8, said control means including a shunt transistor having fifth and sixth output electrodes coupled between a pair of input terminals of said amplifier.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-23 | 1975-11-22 | 1976-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-23 | 1979-11-22 | 1980-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-23 | 1983-11-22 | 1984-05-23 | $7700.00 | Window Closed / Lapsed |