Patent US3621285A successfully refreshed from Google Patents.
US3621285A
Expired / Lapsed
US
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Pulsed excitation voltage circuit for transducers
Assignee: National Aeronautics and Space Administration
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Filing: 1969-10-30
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Granted: 1971-11-16
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Expires: 1989-10-30
Abstract
Abstract A pulsed excitation voltage circuit for a strain gauge bridge is disclosed using a transformer having its primary winding adapted to receive an excitation timing pulse and two secondary windings to turn on two transistor switches adapted to connect positive and negative voltage sources of equal amplitude to opposite ends of the bridge. Voltage limiting diodes are connected to output terminals to limit common-mode voltage spikes resulting from different turn-on and turnoff times of the transistor switches. Each transistor switch includes a base resistor selected at time of assembly to provide substantially equal turn-on times. A speedup capacitor may be used to further equalize turn-on time, and a shunt capacitor may be used at the output of one switch to offset effects of unequal turn-on times.
Inventors
- 👤 Karl F Anderson
- 👤 Thomas L Lynch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:37
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/51; H03K17/56; H03K17/60; H03K17/601; G; G01; G01L; G01L1/00; G01L1/20; G01L1/22; G01L1/225
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
118 words
A pulsed excitation voltage circuit for a transducer having first and second ends and an output terminal therebetween comprising: a first source of voltage of a predetermined amplitude and polarity with respect to a source of reference potential; a second source of voltage of said predetermined amplitude and a polarity opposite the polarity of said first source; first switching means for coupling said first voltage source to said first end of said transducer; second switching means for coupling said second voltage source to said second end of said transducer; means for selectively turning on said first and second switching means at substantially the same time; and means connected to said output terminal for limiting the voltage excursion thereof.
Claim 2
Dependent Claim
118 words
A pulsed excitation voltage circuit for a transducer having first and second ends and an output terminal therebetween comprising: a first source of voltage of a predetermined amplitude and polarity with respect to a source of reference potential; a second source of voltage of said predetermined amplitude and a polarity opposite the polarity of said first source; first switching means for coupling said first voltage source to said first end of said transducer; second switching means for coupling said second voltage source to said second end of said transducer; means for selectively turning on said first and second switching means at substantially the same time; and means connected to said output terminal for limiting the voltage excursion thereof.
Claim 3
Dependent Claim
42 words
Apparatus as defined in claim 1 wherein said means for selectively turning on said first and second switching means comprises a transformer having a primary winding adapted to receive a pulse, and two secondary windings, one for each of said switching means.
Claim 4
Dependent Claim
116 words
Apparatus as defined in claim 2 wherein each of said first and second switching means comprises a junction transistor having a base-emitter junction and a collector-to-emitter circuit, and having one of said secondary windings connected across said base-emitter junction, and having said collector-to-emitter circuit connected in series between one of said first and second voltage sources and one of said first and second ends of said transducer, and wherein each of said transistors includes a resistor in series with one of said secondary windings connected across said base-emitter junction, said resistor having a value selected to control transistor turn-on time such that both transistors turn on at substantially the same time in response to said pulse.
Claim 5
Dependent Claim
22 words
Apparatus as defined in claim 3 including a speedup capacitor in parallel with said series resistor connected to one of said transistors.
Claim 6
Dependent Claim
60 words
Apparatus as defined in claim 1 including a first shunt resistor connected between said source of reference potential and a junction between said first switching means and said first end of said transducer, and a second shunt resistor connected between said source of reference potential and a junction between said second switching means and said second end of said transducer.
Claim 7
Dependent Claim
17 words
Apparatus as defined in claim 4 including a capacitor in parallel with one of said shunt resistors.
Claim 8
Dependent Claim
158 words
A pulsed excitation voltage circuit for a bridge-type transducer having four branches with a first end at a junction between one pair of branches, a second end at a junction between the remaining pair of branches, and first and second output terminals connected to the remaining junctions, comprising: a first source of voltage of a predetermined amplitude and polarity with respect to a source of reference potential; a second source of voltage of said predetermined amplitude and a polarity opposite the polarity of said first source; first switching means for coupling said first voltage source to said first end of said transducer; second switching means for coupling said second voltage source to said second end of said transducer; means for selectively turning on said first and second switching means at substantially the same time; and first and second means connected to said first and second output terminals, respectivelY, for limiting the voltage excursions of said output terminals equally.
Claim 9
Dependent Claim
158 words
A pulsed excitation voltage circuit for a bridge-type transducer having four branches with a first end at a junction between one pair of branches, a second end at a junction between the remaining pair of branches, and first and second output terminals connected to the remaining junctions, comprising: a first source of voltage of a predetermined amplitude and polarity with respect to a source of reference potential; a second source of voltage of said predetermined amplitude and a polarity opposite the polarity of said first source; first switching means for coupling said first voltage source to said first end of said transducer; second switching means for coupling said second voltage source to said second end of said transducer; means for selectively turning on said first and second switching means at substantially the same time; and first and second means connected to said first and second output terminals, respectivelY, for limiting the voltage excursions of said output terminals equally.
Claim 10
Dependent Claim
58 words
Apparatus as defined in claim 7 wherein each of said first and second limiting means comprises a pair of junction diodes connected between one of said output terminals, and said source of reference potential, said diodes of a given pair being oppositely poled such that the cathode of one is connected directly to the anode of the other.
Claim 11
Dependent Claim
42 words
Apparatus as defined in claim 8 wherein said means for selectively turning on said first and second switching means comprises a transformer having a primary winding adapted to receive a pulse, and two secondary windings, one for each of said switching means.
Claim 12
Dependent Claim
116 words
Apparatus as defined in claim 9 wherein each of said first and second switching means comprises a junction transistor having a base-emitter junction and a collector-to-emitter circuit, and having one of said secondary windings connected across said base-emitter junction, and having said collector-to-emitter circuit connected in series between one of said first and second voltage sources and one of said first and second ends of said transducer, and wherein each of said transistors includes a resistor in series with one of said secondary windings connected across said base-emitter junction, said resistor having a value selected to control transistor turn-on time such that both transistors turn on at substantially the same time in response to said pulse.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-15 | 1975-05-17 | 1975-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-15 | 1979-05-17 | 1979-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-15 | 1983-05-17 | 1983-11-16 | $7700.00 | Window Closed / Lapsed |