US3424981A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low level d.c. voltage apparatus employing a balanced modulator and filter means to remove spurious signals
Assignee: Keithley Instruments LLC
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Filing: 1964-11-12
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Granted: 1969-01-28
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Expires: 1984-11-12
Abstract
No abstract record available.
Inventors
- 👤 Robert J Erdman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:33
CPC Classifications
G; G01; G01R; G01R19/00; G01R19/18; H; H03; H03F; H03F3/00; H03F3/38; H03F3/40
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1972-01-28 | 1972-07-29 | 1973-01-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1976-01-28 | 1976-07-29 | 1977-01-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1980-01-28 | 1980-07-29 | 1981-01-28 | $7700.00 | Window Closed / Lapsed |