US4123934A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bridge circuit arrangement for a gas detection instrument
Assignee: Auergesellschaft GmbH
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Filing: 1977-06-20
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Granted: 1978-11-07
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Expires: 1997-06-20
Abstract
Abstract A bridge circuit is provided for a gas-detecting instrument of the type using an electrically-heated resistance element or filament as a sensing element. In order to prevent use of the instrument during the warmup period after initial energization, a portion of the bridge is short-circuited for a predetermined time after energization. The short-circuiting means is preferably a transistor connected across one of the arms of the bridge and controlled by a flip-flop with suitable time-delay circuits for switching the flip-flop.
Inventors
- 👤 Wolfgang Hoht
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 20:12
CPC Classifications
G; G01; G01R; G01R17/00; G01R17/10; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/14; G01N27/18
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
122 words
In combination, a measuring instrument including an electrically-heated resistance sensing element, a plurality of constant resistors connected in a bridge circuit with said sensing element, the bridge circuit including means for measuring change in resistance of said sensing element, a transistor connected across one of said resistors, and control means for said transistor operative upon energization of the sensing element to make the transistor conductive for short-circuiting a portion of the bridge circuit and including time delay means to cause the transistor to revert to the non-conductive state after a predetermined time period to remove the short circuit, said control means comprising a toggle type flip-flop having a resistor-capacitor network to control the time of switching from one state to the other.
Claim 2
Dependent Claim
122 words
In combination, a measuring instrument including an electrically-heated resistance sensing element, a plurality of constant resistors connected in a bridge circuit with said sensing element, the bridge circuit including means for measuring change in resistance of said sensing element, a transistor connected across one of said resistors, and control means for said transistor operative upon energization of the sensing element to make the transistor conductive for short-circuiting a portion of the bridge circuit and including time delay means to cause the transistor to revert to the non-conductive state after a predetermined time period to remove the short circuit, said control means comprising a toggle type flip-flop having a resistor-capacitor network to control the time of switching from one state to the other.
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) | 1981-11-06 | 1982-05-08 | 1982-11-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-11-06 | 1986-05-08 | 1986-11-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-11-06 | 1990-05-08 | 1990-11-07 | $7700.00 | Window Closed / Lapsed |