US2775657A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dual channel amplifying circuit
Assignee: Hartford National Bank and Trust Co
•
Filing: 1952-04-03
•
Granted: 1956-12-25
•
Expires: 1972-04-03
Abstract
No abstract record available.
Inventors
- 👤 Johannes Jacobus Zaalber Zelst
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 02:02
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/52; H03F1/54; H03F1/542; H03F1/34; H03F1/36; H04; H04B; H04B1/00; H04B1/74
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2020317A
Cited
US2210028A
Cited
GB484287A
Cited
GB559258A
Cited
NL56691C
Cited
US2536651A
Cited
US2605333A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1959-12-25 | 1960-06-25 | 1960-12-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1963-12-25 | 1964-06-25 | 1964-12-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1967-12-25 | 1968-06-25 | 1968-12-25 | $7700.00 | Window Closed / Lapsed |