Patent US3207848A successfully refreshed from Google Patents.
US3207848A
Expired / Lapsed
US
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Amplifying circuit for capacitive microphones
Assignee: GEORG NEUMANN LAB fur ELEKTROA
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Filing: 1962-01-12
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Granted: 1965-09-21
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Expires: 1982-01-12
Abstract
No abstract record available.
Inventors
- 👤 Bore Gerhart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 12:05
CPC Classifications
H; H04; H04R; H04R19/00; H04R19/04
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
179 words
AN AMPLIFYING CIRCUIT FOR CAPACTIVE MICROPHONES, COMPRISING AN AMPLIFYING TUBE INCLUDING AND ANODE, A CATHODE AND A CONTROL GRID, A MICROPHONE CAPSULE HAVING TWO TERMINALS, ONE OF SAID TERMINALS BEING CONNECTED WITH SAID GRID OF SAID AMPLIFYING TUBE AND THE OTHER OF SAID TERMINALS BEING CONNECTED WITH AT LEAST ONE CAPACITOR, THE OTHER ELECTRODE OF WHICH IS GROUNDED, A FILTER CHAIN HAVING AT LEAST THREE STAGES AND CONNECTING THE ANODE OF SAID AMPLIFYING TUBE WITH THE CONNECTION OF SAID CAPACITOR AND SAID MICROPHONE CAPSULE, EACH OF SAID STAGES CONSISTING OF ONE SERIES RESISTOR AND ONE BRIDGING CONDENSER, THE OTHER ELECTRODE OF WHICH IS GROUNDED, THE LAST OF SAID BRIDGING CONDENSERS BEING IDENTICAL WITH SAID CAPACITOR CONNECTING SAID MICROPHONE CAPSULE WITH GROUND, THE VOLTAGE OCCURRING AT SAID ANODE OF SAID AMPLIFYING TUBE BEING FED BACK OVER SAID AT LEAST THREE-STAGE CHAIN TO THE CONNECTION OF SAID MICROPHONE CAPSULE WITH SAID LAST CONDENSER, AN ADDITIONAL RESISTOR DISPOSED IN PARALLEL WITH SAID PLURALITY OF RESISTORS, AND SAID ADDITIONAL RESISTOR AND SAID LAST CONDENSER OF SAID FILTER CHAIN FORMING A NEGATIVE FEEDBACK PATH.
Claim 2
Dependent Claim
179 words
AN AMPLIFYING CIRCUIT FOR CAPACTIVE MICROPHONES, COMPRISING AN AMPLIFYING TUBE INCLUDING AND ANODE, A CATHODE AND A CONTROL GRID, A MICROPHONE CAPSULE HAVING TWO TERMINALS, ONE OF SAID TERMINALS BEING CONNECTED WITH SAID GRID OF SAID AMPLIFYING TUBE AND THE OTHER OF SAID TERMINALS BEING CONNECTED WITH AT LEAST ONE CAPACITOR, THE OTHER ELECTRODE OF WHICH IS GROUNDED, A FILTER CHAIN HAVING AT LEAST THREE STAGES AND CONNECTING THE ANODE OF SAID AMPLIFYING TUBE WITH THE CONNECTION OF SAID CAPACITOR AND SAID MICROPHONE CAPSULE, EACH OF SAID STAGES CONSISTING OF ONE SERIES RESISTOR AND ONE BRIDGING CONDENSER, THE OTHER ELECTRODE OF WHICH IS GROUNDED, THE LAST OF SAID BRIDGING CONDENSERS BEING IDENTICAL WITH SAID CAPACITOR CONNECTING SAID MICROPHONE CAPSULE WITH GROUND, THE VOLTAGE OCCURRING AT SAID ANODE OF SAID AMPLIFYING TUBE BEING FED BACK OVER SAID AT LEAST THREE-STAGE CHAIN TO THE CONNECTION OF SAID MICROPHONE CAPSULE WITH SAID LAST CONDENSER, AN ADDITIONAL RESISTOR DISPOSED IN PARALLEL WITH SAID PLURALITY OF RESISTORS, AND SAID ADDITIONAL RESISTOR AND SAID LAST CONDENSER OF SAID FILTER CHAIN FORMING A NEGATIVE FEEDBACK PATH.
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) | 1968-09-20 | 1969-03-22 | 1969-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1972-09-20 | 1973-03-22 | 1973-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1976-09-20 | 1977-03-22 | 1977-09-21 | $7700.00 | Window Closed / Lapsed |