Patent US2740948A successfully refreshed from Google Patents.
US2740948A
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US
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Electronic ringing frequency generator
Assignee: Automatic Electric Laboratories Inc
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Filing: 1952-10-08
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Granted: 1956-04-03
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Expires: 1972-10-08
Abstract
No abstract record available.
Inventors
- 👤 Harold J Mccreary
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:23
CPC Classifications
H; H04; H04M; H04M19/00; H04M19/02; H03; H03B; H03B5/00; H03B5/08; H03B5/10
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1105492A
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US1957672A
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US1904929A
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US2122499A
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US2188159A
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US2168198A
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US2359967A
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US2583792A
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US2600729A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1959-04-03 | 1959-10-03 | 1960-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1963-04-03 | 1963-10-03 | 1964-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1967-04-03 | 1967-10-03 | 1968-04-03 | $7700.00 | Window Closed / Lapsed |