Patent US1926568A successfully refreshed from Google Patents.
US1926568A
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US
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Direct current amplifier and method of operating same
Assignee: Stanolind Oil and Gas Co
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Filing: 1930-02-21
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Granted: 1933-09-12
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Expires: 1950-02-21
Abstract
No abstract record available.
Inventors
- 👤 Frank C Walz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:12
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/34; H03F3/36
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) | 1936-09-11 | 1937-03-13 | 1937-09-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1940-09-11 | 1941-03-13 | 1941-09-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1944-09-11 | 1945-03-13 | 1945-09-12 | $7700.00 | Window Closed / Lapsed |