Patent US3544720A successfully refreshed from Google Patents.
US3544720A
Expired / Lapsed
US
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Protective circuit for loudspeaker
Assignee: MCINTOSH LAB Inc
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Filing: 1969-03-26
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Granted: 1970-12-01
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Expires: 1989-03-26
Abstract
No abstract record available.
Inventors
- 👤 Sidney A Corderman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 08:44
CPC Classifications
H; H04; H04R; H04R3/00; H04R3/007; H02; H02H; H02H9/00; H02H9/04; H02H9/041; H03; H03F; H03F1/00; H03F1/52
Claims Analysis
Total Claims: 0
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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) | 1973-11-30 | 1974-06-01 | 1974-12-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-11-30 | 1978-06-01 | 1978-12-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-11-30 | 1982-06-01 | 1982-12-01 | $7700.00 | Window Closed / Lapsed |