Patent US3588690A successfully refreshed from Google Patents.
US3588690A
Expired / Lapsed
US
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Test circuit including bridge type oscillator means for monitoring equivalent series resistance of quartz crystals
Assignee: Individual
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Filing: 1969-07-16
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Granted: 1971-06-28
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Expires: 1989-07-16
Abstract
Abstract A CIRCUIT FOR TESTING THE SERIES EQUIVALENT RESISTANCE OF QUARTZ CRYSTALS HAVING A QUARTZ CRYSTAL FOR TEST IN A BRIDGE CIRCUIT COUPLED TO A DIFFERENTIAL AMPLIFIER WITH THE OUTPUT THEREOF FED BACK TO THE BRIDGE CIRCUIT PRODUCING AN OSCILLATOR THAT WILL OSCILLATE WHEN THE EQUIVALENT RESISTANCE OF THE CRYSTAL IS LESS THAN A PREDETERMINED RESISTANCE IN THE BRIDGE CIRCUIT AND STOP OSCILLATION WHEN THE CRYSTAL EQUIVALENT RESISTANCE EQUALS OR EXCEEDS THE PREDETERMINED RESISTANCE, THE OUTPUT OF THE DIFFERENTIAL AMPLIFIER BEING OPERATIVE TO DRIVE AN INDICATOR OF THE OSCILLATOR CONDITION AND THUS INDICATE THE RESISTANCE VALUE ABOVE OR BELOW THE PREDETERMINED RESISTANCE VALUE.
Inventors
- 👤 Hugh Allen Griffin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:05
CPC Classifications
G; G01; G01R; G01R29/00; G01R29/22
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) | 1974-06-27 | 1974-12-27 | 1975-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-27 | 1978-12-27 | 1979-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-27 | 1982-12-27 | 1983-06-28 | $7700.00 | Window Closed / Lapsed |