US3988640A
Expired / Lapsed
US
⏱️ 0.0 years remaining
A.C. protective circuit
Assignee: Boeing North American Inc
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Filing: 1975-05-27
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Granted: 1976-10-26
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Expires: 1995-05-27
Abstract
Abstract An electronic device is protected from excessive A. C. voltages by a diode in series with the A. C. signal path which is forward biased from a shunt D. C. power supply for passing desired A. C. signals without distortion and which is reverse biased by a series capacitor which is charged through a shunt threshold device whenever the A. C. voltage exceeds a predetermined level and is discharged through a shunt path thereafter.
Inventors
- 👤 James R. King
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 12:46
CPC Classifications
H; H02; H02H; H02H9/00; H02H9/04
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
130 words
An A. C. protective circuit for protecting an electronic device from excessive A. C. voltages, comprising: a diode connected in series with the A. C. signal path to the electronic device; a capacitor connected in series with said signal path; D. c. power supply means connected to the terminals of said diode for forward biasing it, including means for blocking the passage of A. C. current; threshold means connected in shunt with said signal path for providing a path to charge said capacitor from the A. C. signal with a polarity for reverse biasing said diode whenever the voltage across said threshold means exceeds a predetermined level, and discharge means connected to the terminals of said capacitor for discharging it, including means for blocking the passage of A. C. current.
Claim 2
Dependent Claim
130 words
An A. C. protective circuit for protecting an electronic device from excessive A. C. voltages, comprising: a diode connected in series with the A. C. signal path to the electronic device; a capacitor connected in series with said signal path; D. c. power supply means connected to the terminals of said diode for forward biasing it, including means for blocking the passage of A. C. current; threshold means connected in shunt with said signal path for providing a path to charge said capacitor from the A. C. signal with a polarity for reverse biasing said diode whenever the voltage across said threshold means exceeds a predetermined level, and discharge means connected to the terminals of said capacitor for discharging it, including means for blocking the passage of A. C. current.
Claim 3
Dependent Claim
32 words
The A. C. protective circuit of claim 1 wherein the electronic device is a radio receiver and the A. C. signal is an R. F. signal picked up by the receiver antenna.
Claim 4
Dependent Claim
20 words
The A. C. protective circuit of claim 1 wherein said D. C. power supply means comprises a constant current source.
Claim 5
Dependent Claim
20 words
The A. C. protective circuit of claim 1 wherein said capacitor discharge is via said D. C. power supply means.
Claim 6
Dependent Claim
16 words
The A. C. protective circuit of claim 1 wherein said threshold means is a clamping device.
Claim 7
Dependent Claim
15 words
The A. C. protective circuit of claim 5 wherein said threshold means is a diode.
Claim 8
Dependent Claim
19 words
The A. C. protective circuit of claim 1 wherein the discharge period of said capacitor exceeds its charging period.
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) | 1979-10-26 | 1980-04-26 | 1980-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-10-26 | 1984-04-26 | 1984-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-10-26 | 1988-04-26 | 1988-10-26 | $7700.00 | Window Closed / Lapsed |