US137730A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Improvement in circuits for electro-magnets
Assignee: —
•
Filing: —
•
Granted: 1873-04-08
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Expires: 1890-04-08
Abstract
No abstract record available.
Inventors
No inventors recorded.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 00:58
CPC Classifications
H; H01; H01H; H01H47/00; H01H47/02; H01H47/18; H03; H03K; H03K17/00; H03K17/51; H03K17/56; H03K17/60; H03K17/64
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) | 1876-04-07 | 1876-10-07 | 1877-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1880-04-07 | 1880-10-07 | 1881-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1884-04-07 | 1884-10-07 | 1885-04-08 | $7700.00 | Window Closed / Lapsed |