US3721968A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic pickup
Assignee: ELECTRO CORP AMERICA
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Filing: 1972-02-02
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Granted: 1973-03-20
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Expires: 1992-02-02
Abstract
Abstract A magnetic pickup having an electronic switch circuit incorporated in the sensing unit to generate a high level digital signal, improving the signal form and the signal-to-noise ratio. The switch has an input transistor with a base bias circuit including a diode having a characteristic comparable with that of the base emitter junction of the input transistor, to stabilize the bias and the sensitivity of the switch. In one form of the invention, the emitter coupling element of the transistorized switching circuit has a constant voltage independent of the supply potential, enabling the use of one circuit over a range of operating voltages.
Inventors
- 👤 G Gee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 04:52
CPC Classifications
G; G01; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/48; G01P3/4802; G01P3/481; G01P3/488
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
247 words
A magnetic pickup sensing system having a digital signal output, comprising: a coil subject to a change in magnetic flux linkage due to relative movement between the coil and a body of magnetic material, which movement induces a voltage across the coil; a source of operating potential; regenerative electronic switch means having input and output stages, each with a control element and an output circuit, the control element of the output stage being connected with the output circuit of the input stage, the output circuits of both stages being connected across said source of operating potential, and feedback circuit means connected between the stages, each stage having stable, complementary conductive and nonconductive conditions; a bias circuit means connected with said source of operating potential and having a point therein with a potential which, when applied as a bias to the control element of the input stage, establishes a stable conditIon of said switch means; an input circuit connecting said coil in series between said point in the bias circuit means and the control element of the input stage of said switch means, the bias potential being applied to said control element through said coil, an induced voltage of one polarity across said coil causing both stages of said switch means to change from one conduction condition to the other; and means connected with an output circuit of the switch means for deriving therefrom a digital signal which is a function of the voltage induced across said coil.
Claim 2
Dependent Claim
247 words
A magnetic pickup sensing system having a digital signal output, comprising: a coil subject to a change in magnetic flux linkage due to relative movement between the coil and a body of magnetic material, which movement induces a voltage across the coil; a source of operating potential; regenerative electronic switch means having input and output stages, each with a control element and an output circuit, the control element of the output stage being connected with the output circuit of the input stage, the output circuits of both stages being connected across said source of operating potential, and feedback circuit means connected between the stages, each stage having stable, complementary conductive and nonconductive conditions; a bias circuit means connected with said source of operating potential and having a point therein with a potential which, when applied as a bias to the control element of the input stage, establishes a stable conditIon of said switch means; an input circuit connecting said coil in series between said point in the bias circuit means and the control element of the input stage of said switch means, the bias potential being applied to said control element through said coil, an induced voltage of one polarity across said coil causing both stages of said switch means to change from one conduction condition to the other; and means connected with an output circuit of the switch means for deriving therefrom a digital signal which is a function of the voltage induced across said coil.
Claim 3
Dependent Claim
146 words
The sensing system of claim 1 in which the input stage of the switch means is a transistor with a base control element, said bias circuit means for the switch means including a resistor and diode connected in series across said source forming a voltage divider, said coil being connected from the junction between the resistor and diode in the bias circuit means to the base of said transistor, applying the bias potential developed across the diode to the base of the transistor rendering the transistor nonconductive in the absence of a voltage induced across said coil, the base circuit of said transistor drawing current through said resistor when the transistor conducts in response to a voltage induced across said coil, reducing the voltage across said diode and introducing hysteresis which stabilizes operation of the switch means with a low amplitude induced voltage across said coil.
Claim 4
Dependent Claim
49 words
The sensing system of claim 1 in which the input stage of the switch means is a transistor having a base control element, and including a pair of reversely connected diodes in parallel across said coil limiting the amplitude of the voltage applied to the base of said transistor.
Claim 5
Dependent Claim
59 words
The sensing system of claim 1 in which the input stage of the switch means is a transistor having a base control element, and said system includes means establishing a reference potential and a pair of diodes, one connected from each end of said coil to said reference potential means to limit the reverse bias applied to said transistor.
Claim 6
Dependent Claim
55 words
The sensing system of claim 1 in which the input stage of the switch means is a transistor having a base control element, and said system includes means establishing a reference potential and a resistor connected from the base of said transistor to said reference voltage means to enhance the stability of the switch means.
Claim 7
Dependent Claim
27 words
The sensing system of claim 1 in which the bias circuit means includes a voltage divider and the bias potential is developed at an intermediate point thereof.
Claim 8
Dependent Claim
28 words
The sensing system of claim 1 in which said feedback circuit means includes a common resistor connected in the output circuits of both stages of said switch means.
Claim 9
Dependent Claim
28 words
The sensing system of claim 7 in which both stages of said switch means are transistors and said common resistor is connected with the emitters of each transistor.
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) | 1976-03-19 | 1976-09-18 | 1977-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-19 | 1980-09-18 | 1981-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-19 | 1984-09-18 | 1985-03-20 | $7700.00 | Window Closed / Lapsed |