US3557309A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Amplifier with automatic gain control
Assignee: Individual
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Filing: 1967-10-02
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Granted: 1971-01-19
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Expires: 1987-10-02
Abstract
Abstract A solid state amplifier supplying a modulating signal to a transmitter or audio reproducing device with an automatically varied gain to maintain a substantially constant output range. Audio inputs to the amplifier from microphones of different impedance values are accommodated by a sliding switch control that changes the impedance of the coupling circuit between the microphone and the initial amplifier stage. A field effect transistor is employed in a signal attenuating network to limit the gain of an automatically controlled amplifier stage coupled to the amplifier output through an impedance matching network monitored by the signal attenuating network.
Inventors
- 👤 Cecil R Graham
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 02:04
CPC Classifications
H; H03; H03G; H03G1/00; H03G1/0005; H03G1/0035; H03G1/007; H03G3/00; H03G3/02; H03G3/04; H03G3/10; H03G3/12; H03G3/20; H03G3/30; H03G3/3005; H03G3/301; H03G3/3015
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
142 words
An amplifier assembly for an input signal source having significAntly different input impedances, including a variable gain amplifier connected to the input signal source, impedance matching means connected to the variable gain amplifier establishing a low impedance path for amplified output signals, means connected to the impedance matching means for sampling the output signals conducted therethrough, a regulated source of voltage, a resistor connected to said source means coupling said source of voltage through the resistor to the variable gain amplifier, signal varied resistive means connected in parallel with the coupling means for limiting the signal gain of the variable gain amplifier, and attenuating means connecting the sampling means to the signal varied resistive means for varying the resistance thereof when the signal level of said output signals exceeds a limiting value to reduce the signal gain of the variable gain amplifier.
Claim 2
Dependent Claim
142 words
An amplifier assembly for an input signal source having significAntly different input impedances, including a variable gain amplifier connected to the input signal source, impedance matching means connected to the variable gain amplifier establishing a low impedance path for amplified output signals, means connected to the impedance matching means for sampling the output signals conducted therethrough, a regulated source of voltage, a resistor connected to said source means coupling said source of voltage through the resistor to the variable gain amplifier, signal varied resistive means connected in parallel with the coupling means for limiting the signal gain of the variable gain amplifier, and attenuating means connecting the sampling means to the signal varied resistive means for varying the resistance thereof when the signal level of said output signals exceeds a limiting value to reduce the signal gain of the variable gain amplifier.
Claim 3
Dependent Claim
66 words
The combination of claim 1 wherein said signal varied resistive means comprises a field effect transistor having a gate, a drain connected to ground and a source connected to the coupling means, said attenuating means including a pair of directionally aligned and series connected diodes respectively connected to the gate and ground and an input juncture connecting opposite terminals of the diodes to the sampling means.
Claim 4
Dependent Claim
36 words
The combination of claim 2 including an audio frequency amplifying stage connecting the signal source to the variable gain amplifier, said signal source including an impedance changing input assembly coupled to the audio frequency amplifying stage.
Claim 5
Dependent Claim
52 words
The combination of claim 3 wherein said input assembly comprises s signal transformer having a primary winding and a secondary winding, a signal coupling capacitor connecting the audio frequency amplifying stage to said secondary winding, and impedance controlling switch means for selectively bypassing portions of the primary winding or both transformer windings.
Claim 6
Dependent Claim
36 words
The combination of claim 1 including a low frequency amplifying stage connecting the signal source to the variable gain amplifier, said signal source including an impedance changing input assembly coupled to the low frequency amplifying stage.
Claim 7
Dependent Claim
142 words
An audio amplifier assembly for supplying a gain-controlled modulating signal comprising a pair of series connected transistor stages in common-emitter configurations having input bases, output collectors and emitters, a high frequency bypass capacitor connected to the emitter of a first of the transistor stages, an emitter-follower transistor having an output emitter and a base coupled to the collector of the second of said transistor stages, a control signal amplifier coupled to the output emitter of said emitter-follower transistor, a field effect transistor having a biased gate, a source and a drain connected to ground, a pair of diodes unidirectionally connected in series between ground and said gate forming a juncture coupled to the output of the control signal amplifier, and a gain controlling capacitor connecting the source of the field effect transistor to the emitter of said second of the transistor stages.
Claim 8
Dependent Claim
142 words
An audio amplifier assembly for supplying a gain-controlled modulating signal comprising a pair of series connected transistor stages in common-emitter configurations having input bases, output collectors and emitters, a high frequency bypass capacitor connected to the emitter of a first of the transistor stages, an emitter-follower transistor having an output emitter and a base coupled to the collector of the second of said transistor stages, a control signal amplifier coupled to the output emitter of said emitter-follower transistor, a field effect transistor having a biased gate, a source and a drain connected to ground, a pair of diodes unidirectionally connected in series between ground and said gate forming a juncture coupled to the output of the control signal amplifier, and a gain controlling capacitor connecting the source of the field effect transistor to the emitter of said second of the transistor stages.
Claim 9
Dependent Claim
80 words
The combination of claim 1 wherein said signal varied resistive means comprises a current conducting device having power terminals directly connected between ground and said source of voltage in parallel relation to the coupling means and a control terminal for maintaining a predetermined static resistance between the power terminals while the signal level of the output signals is below said limiting value, the static resistance being determined by the potential difference between the source of voltage and the control terminal.
Claim 10
Dependent Claim
63 words
The combination of claim 1 wherein said attenuating means includes diode means connected between the control terminal and ground for normally blocking voltage signals from the monitoring means and signal amplifying means connected to the monitoring means for rendering the diode means conductive in response to output signals exceeding said limiting value to change the sTatic resistance of the signal varied resistive means.
Claim 11
Dependent Claim
121 words
The combination of claim 8 wherein said signal source includes an input signal transformer having a tapped primary winding and a secondary winding, a pair of input terminals, a pair of output terminals coupled to the amplifier assembly and a switch device displaceable between a plurality of operative positions in electrical contact with the input and output terminals, said switch device having means for establishing direct conductive paths between the input and output terminals in one of the operative positions, means for electrically connecting the input terminals across different tapped portions of the primary winding in the other of the operative positions and means for electrically connecting the output terminals across the secondary winding in said other of the operating positions.
Claim 12
Dependent Claim
121 words
The combination of claim 1 wherein said signal source includes an input signal transformer having a tapped primary winding and a secondary winding, a pair of input terminals, a pair of output terminals coupled to the amplifier assembly and a switch device displaceable between a plurality of operative positions in electrical contact with the input and output terminals, said switch device having means for establishing direct conductive paths between the input and output terminals in one of the operative positions, means for electrically connecting the input terminals across different tapped portions of the primary winding in the other of the operative positions and means for electrically connecting the output terminals across the secondary winding in said other of the operating positions.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-01-18 | 1974-07-20 | 1975-01-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-18 | 1978-07-20 | 1979-01-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-18 | 1982-07-20 | 1983-01-19 | $7700.00 | Window Closed / Lapsed |