Patent US921702A successfully refreshed from Google Patents.
US2139489A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Frequency responsive relay
Assignee: General Electric Co
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Filing: 1936-08-27
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Granted: 1938-12-06
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Expires: 1956-08-27
Abstract
No abstract record available.
Inventors
- 👤 William D Cockrell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 22:47
CPC Classifications
G; G01; G01R; G01R23/00; G01R23/02
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) | 1941-12-05 | 1942-06-06 | 1942-12-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1945-12-05 | 1946-06-06 | 1946-12-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1949-12-05 | 1950-06-06 | 1950-12-06 | $7700.00 | Window Closed / Lapsed |