Patent US2255757A successfully refreshed from Google Patents.
US2255757A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Audio frequency amplifier
Assignee: RCA Corp
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Filing: 1939-07-29
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Granted: 1941-09-16
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Expires: 1959-07-29
Abstract
No abstract record available.
Inventors
- 👤 Rudolph A Bierwirth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 20:07
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/02; H03G3/04; H03G3/06; H03G3/08
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) | 1944-09-15 | 1945-03-17 | 1945-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1948-09-15 | 1949-03-17 | 1949-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1952-09-15 | 1953-03-17 | 1953-09-16 | $7700.00 | Window Closed / Lapsed |