Patent US1839301A successfully refreshed from Google Patents.
US1839301A
Expired / Lapsed
US
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Polyphase filter circuit
Assignee: Federal Telegraph Co
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Filing: 1927-05-07
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Granted: 1932-01-05
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Expires: 1947-05-07
Abstract
No abstract record available.
Inventors
- 👤 Jr Robert D Duncan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 11:52
CPC Classifications
H; H03; H03H; H03H7/00; H03H7/01; H03H7/17; H03H7/1741; H03H7/175; H03H7/0115; H03H7/1775
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) | 1935-01-04 | 1935-07-06 | 1936-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1939-01-04 | 1939-07-06 | 1940-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1943-01-04 | 1943-07-06 | 1944-01-05 | $7700.00 | Window Closed / Lapsed |