US3761775A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Protective circuit
Assignee: Pioneer Corp
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Filing: 1971-11-16
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Granted: 1973-09-25
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Expires: 1991-11-16
Abstract
Abstract A protective circuit for protecting an output circuit and a load circuit of a signal amplifier from abnormal conditions and including a differential amplifier for detecting the abnormal conditions of the output circuit and the load circuit. The circuit is particularly useful for protection of an outputcondenser-less amplifier.
Inventors
- 👤 A Ozawa
- 👤 S Fujie
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:16
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/52
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
159 words
A protective circuit for protecting an output stage of a signal amplifier comprising: a. a normally balanced differential amplifier having a first input connected to the input, and a second input coupled to the output, of said signal amplifier, said differential amplifier being responsive to an abnormal condition of said signal amplifier to go into an unbalanced state to produce a control signal at its output, b. normally unoperated switching means connected to the output of said differential amplifier and operative to protect the output stage of said signal amplifier from abnormal conditions, said switching means being operated by said control signal when said differential amplifier goes into an unbalanced state, and c. an attenuation circuit having an input connected to said output of said signal amplifier and having an output connected to said second input of said differential amplifier, said attenuation circuit having an attenuation factor of the same magnitude as the amplification factor of said signal amplifier.
Claim 2
Dependent Claim
159 words
A protective circuit for protecting an output stage of a signal amplifier comprising: a. a normally balanced differential amplifier having a first input connected to the input, and a second input coupled to the output, of said signal amplifier, said differential amplifier being responsive to an abnormal condition of said signal amplifier to go into an unbalanced state to produce a control signal at its output, b. normally unoperated switching means connected to the output of said differential amplifier and operative to protect the output stage of said signal amplifier from abnormal conditions, said switching means being operated by said control signal when said differential amplifier goes into an unbalanced state, and c. an attenuation circuit having an input connected to said output of said signal amplifier and having an output connected to said second input of said differential amplifier, said attenuation circuit having an attenuation factor of the same magnitude as the amplification factor of said signal amplifier.
Claim 3
Dependent Claim
28 words
A protective circuit as set forth in claim 1, wherein said switching means comprises a switching circuit having a switch contact in the output of said signal amplifier.
Claim 4
Dependent Claim
17 words
A protective circuit as set forth in claim 1, wherein said signal amplifier is an output-condenser-less amplifier.
References Cited (Backward Citations)
US3058036A
Cited
US3219911A
Cited
US3250981A
Cited
US3497794A
Cited
US3486128A
Cited
US3550025A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-24 | 1977-03-26 | 1977-09-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-24 | 1981-03-26 | 1981-09-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-24 | 1985-03-26 | 1985-09-25 | $7700.00 | Window Closed / Lapsed |