US3962607A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Loudspeaker protective system
Assignee: DYNACO Inc
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Filing: 1974-06-05
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Granted: 1976-06-08
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Expires: 1994-06-05
Abstract
Abstract A protective circuit for a loudspeaker connected to the output of an audio amplifier, in which a predetermined fraction of the voltage derived from the output of the power amplifier is peak rectified and stored in an accumulator provided with resistors for leaking charge from the accumulator at a predetermined rate. The voltage across the storage capacitor is normally maintained blocked in respect to application to a diode control circuit for by-passing input signal to the power amplifier. When the voltage across the storage capacitor attains a sufficiently high value, control signal is applied to oppositely poled diodes, to vary their back biases, and the diodes provide a controlled shunt path to ground for peaks of the signal applied to the input to the power amplifier.
Inventors
- 👤 Wade D. Burns
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:18
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/20; H02H3/08; H02H3/093; H03; H03F; H03F1/00; H03F1/52
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
216 words
In a protective circuit, a loudspeaker, a source of audio signal, a power amplifier having an input terminal and an output terminal, means connecting said source to said input terminal, means connecting said loudspeaker to said output terminal, means for deriving a predetermined fraction of the voltage at said output terminal at a further terminal, means rectifying the voltage on said further terminal and deriving a peak rectified voltage, accumulator means for accumulating said peak rectified voltage, said accumulator means having a relatively long time constant on discharge and a relatively short time constant on charge, a voltage responsive control circuit, means coupling said accumulator means to said voltage responsive control circuit, said means coupling including diode means poled to be forward biased by the voltage of said accumulator means, reference voltage means biasing said diode means to render said diode means non-conductive of said voltage of said accumulator means only while said voltage of said accumulator means is below a predetermined level indicative of a safe level of voltage drive of said loudspeaker, and means responsive to conductivity of said diode means for controlling by-pass of peaks of voltage at said input terminal as a function of said voltage of said accumulator means only sufficiently to reduce voltage into said loudspeaker to said safe level.
Claim 2
Dependent Claim
216 words
In a protective circuit, a loudspeaker, a source of audio signal, a power amplifier having an input terminal and an output terminal, means connecting said source to said input terminal, means connecting said loudspeaker to said output terminal, means for deriving a predetermined fraction of the voltage at said output terminal at a further terminal, means rectifying the voltage on said further terminal and deriving a peak rectified voltage, accumulator means for accumulating said peak rectified voltage, said accumulator means having a relatively long time constant on discharge and a relatively short time constant on charge, a voltage responsive control circuit, means coupling said accumulator means to said voltage responsive control circuit, said means coupling including diode means poled to be forward biased by the voltage of said accumulator means, reference voltage means biasing said diode means to render said diode means non-conductive of said voltage of said accumulator means only while said voltage of said accumulator means is below a predetermined level indicative of a safe level of voltage drive of said loudspeaker, and means responsive to conductivity of said diode means for controlling by-pass of peaks of voltage at said input terminal as a function of said voltage of said accumulator means only sufficiently to reduce voltage into said loudspeaker to said safe level.
Claim 3
Dependent Claim
37 words
The combination according to claim 1, including means responsive to said voltage of said accumulator means for operating a visual indicator only in response to at least a predetermined fraction of said voltage of said accumulator means.
Claim 4
Dependent Claim
62 words
The combination according to claim 1, wherein said reference voltage means includes further diode means connected in a loop consisting of said diode means, said accumulator means and said further diode means, a source of dc voltage, a voltage dropping resistance, means connecting said source of dc voltage, said resistive voltage dropping resistance and said further diode means in a series circuit.
Claim 5
Dependent Claim
42 words
The combination according to claim 3, wherein said means for controlling bypass includes back to back diodes connected between said input terminal and ground, and means responsive to the voltage across said further diode for back biasing said back to back diodes.
Claim 6
Independent Claim
245 words
A system for protecting an audio amplifier load from audio overvoltage provided by an audio amplifier, comprising means responsive to the peak output voltage of said amplifier for time averaging said peak output voltage and means responsive to the time averaged peak output voltage for reducing said over voltage by controllably by-passing audio input voltage to said amplifier only by such amounts directly related to the excess of said averaged peak output voltage above a predetermined limiting value so as to limit said peak output voltage to said predetermined limiting value, wherein said means responsive to the time averaged peak output voltage includes a storage capacitor for storing said time averaged peak output voltage, at least a first diode, at least a second diode, means connecting corresponding electrodes of said at least a first diode and said at least a second diode to a common junction, means connecting the remaining electrodes of said at least a first diode and said at least a second diode to opposite plates of said storage capacitor, a source of dc voltage, a resistance, means connecting said source of voltage and said resistance in series with said at least a second diode, the polarity of said at least a second diode and of said source of voltage being such that said at least a second diode is conductive, and the polarity of the voltage on said storage capacitor being such as to forward bias said at least a first diode.
Claim 7
Independent Claim
245 words
A system for protecting an audio amplifier load from audio overvoltage provided by an audio amplifier, comprising means responsive to the peak output voltage of said amplifier for time averaging said peak output voltage and means responsive to the time averaged peak output voltage for reducing said over voltage by controllably by-passing audio input voltage to said amplifier only by such amounts directly related to the excess of said averaged peak output voltage above a predetermined limiting value so as to limit said peak output voltage to said predetermined limiting value, wherein said means responsive to the time averaged peak output voltage includes a storage capacitor for storing said time averaged peak output voltage, at least a first diode, at least a second diode, means connecting corresponding electrodes of said at least a first diode and said at least a second diode to a common junction, means connecting the remaining electrodes of said at least a first diode and said at least a second diode to opposite plates of said storage capacitor, a source of dc voltage, a resistance, means connecting said source of voltage and said resistance in series with said at least a second diode, the polarity of said at least a second diode and of said source of voltage being such that said at least a second diode is conductive, and the polarity of the voltage on said storage capacitor being such as to forward bias said at least a first diode.
Claim 8
Dependent Claim
27 words
The combination according to claim 5 wherein said at least a first diode is two diodes and said at least a second diode is a single diode.
Claim 9
Dependent Claim
115 words
A control circuit, including a storage capacitor, a charging resistance connected in series with said capacitor, a discharging resistance in shunt to said capacitor, said discharging resistance being larger than said charging resistance, a source of dc positive voltage greater than several volts, a further resistance, a first diode, a circuit connecting said source, said further resistance and said first diode in the order named in a first conductive circuit, a second pair of series diodes having a cathode connected to said capacitor and an anode connected to the junction of said first diode and said resistance, means deriving a control voltage from said junction, and means charging said capacitor negatively to a variable extent.
Claim 10
Dependent Claim
115 words
A control circuit, including a storage capacitor, a charging resistance connected in series with said capacitor, a discharging resistance in shunt to said capacitor, said discharging resistance being larger than said charging resistance, a source of dc positive voltage greater than several volts, a further resistance, a first diode, a circuit connecting said source, said further resistance and said first diode in the order named in a first conductive circuit, a second pair of series diodes having a cathode connected to said capacitor and an anode connected to the junction of said first diode and said resistance, means deriving a control voltage from said junction, and means charging said capacitor negatively to a variable extent.
Claim 11
Dependent Claim
46 words
The combination according to claim 7, wherein is provided a power amplifier, peak rectifying means responsive to the output of said amplifier for supplying voltage to said means for charging, and diode means responsive to said control voltage for controllably clipping input signal from said amplifier.
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) | 1979-06-08 | 1979-12-08 | 1980-06-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-06-08 | 1983-12-08 | 1984-06-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-06-08 | 1987-12-08 | 1988-06-08 | $7700.00 | Window Closed / Lapsed |