US4031559A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Filter capacitor charging circuit
Assignee: AT&T Inc
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Filing: 1975-12-10
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Granted: 1977-06-21
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Expires: 1995-12-10
Abstract
Abstract A circuit is disclosed for charging an input filter capacitance from a source of potential before a protective circuit, e.g., a fuse, is established between the source of potential and the capacitance. If the charging circuit is connected between the potential source and the substantially discharged capacitance, a small charging current will flow through a current limiting resistance. This small current will partially charge the capacitance if no faults are present. A threshold detector circuit monitors the voltage on the capacitance and for a voltage of approximately three volts or more, in the case of a twenty-four volt potential source, activates a charging transistor. The charging transistor is controlled by feedback circuitry to provide a larger but limited charging current to complete the charging to within approximately one volt of the potential of the source of potential.
Inventors
- 👤 Daniel Vern Peters
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 00:23
CPC Classifications
H; H02; H02H; H02H9/00; H02H9/001
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
152 words
A circuit for charging an input filter capacitance from a source of potential having a battery terminal and a ground terminal comprising: an input connected to the battery terminal, and an output for connection to the capacitance; a first charging circuit comprising two resistors connected in series between said input and said output; a threshold detecting circuit comprising first semiconductor switching means connected to said ground terminal and having an output terminal and a control terminal, and diode means connected between said output and said control terminal of said first semiconductor switching means; a second charging circuit comprising second semiconductor switching means connected between the junction of said two resistors and said output and having a control terminal, and diode means interconnecting said battery terminal and said control terminal of said second semiconductor switching means; and means for coupling said output terminal to said control terminal of said second semiconductor switching means.
Claim 2
Dependent Claim
152 words
A circuit for charging an input filter capacitance from a source of potential having a battery terminal and a ground terminal comprising: an input connected to the battery terminal, and an output for connection to the capacitance; a first charging circuit comprising two resistors connected in series between said input and said output; a threshold detecting circuit comprising first semiconductor switching means connected to said ground terminal and having an output terminal and a control terminal, and diode means connected between said output and said control terminal of said first semiconductor switching means; a second charging circuit comprising second semiconductor switching means connected between the junction of said two resistors and said output and having a control terminal, and diode means interconnecting said battery terminal and said control terminal of said second semiconductor switching means; and means for coupling said output terminal to said control terminal of said second semiconductor switching means.
Claim 3
Dependent Claim
34 words
A circuit in accordance with claim 1 further comprising: a comparator circuit connected between said input and said output to generate a control signal to control said coupling means which comprises semiconductor switching means.
Claim 4
Dependent Claim
23 words
A circuit in accordance with claim 2 further comprising a relay responsive to said control signal to connect said input to said output.
Claim 5
Dependent Claim
177 words
A circuit for charging an input filter capacitance comprising: a source of potential having a battery terminal and a ground terminal; an input connected to said battery terminal, and an output; a first resistor and a second resistor connected in series between said input and said output; a first transistor of one conductivity type having a base, an emitter, and a collector, said emitter connected to the junction of said first and second resistors and said collector connected to said output; first diode means coupling said battery terminal to said base; a second transistor of the opposite conductivity type having a base, an emitter and a collector, said emitter of said second transistor connected to said ground terminal; a series combination of a third resistor and second diode means connecting said output to said base of said second transistor; means for connecting said base of said first transistor to said collector of said second transistor; and a parallel combination of a fifth resistor and a capacitor connecting said base of said second transistor to said ground terminal.
Claim 6
Dependent Claim
177 words
A circuit for charging an input filter capacitance comprising: a source of potential having a battery terminal and a ground terminal; an input connected to said battery terminal, and an output; a first resistor and a second resistor connected in series between said input and said output; a first transistor of one conductivity type having a base, an emitter, and a collector, said emitter connected to the junction of said first and second resistors and said collector connected to said output; first diode means coupling said battery terminal to said base; a second transistor of the opposite conductivity type having a base, an emitter and a collector, said emitter of said second transistor connected to said ground terminal; a series combination of a third resistor and second diode means connecting said output to said base of said second transistor; means for connecting said base of said first transistor to said collector of said second transistor; and a parallel combination of a fifth resistor and a capacitor connecting said base of said second transistor to said ground terminal.
Claim 7
Dependent Claim
117 words
A circuit for charging an input filter capacitance in accordance with claim 4 further comprising: a comparator circuit having two input terminals and an output terminal, one of said input terminals connected to said input and the other of said input terminals connected to said output; said connecting means comprising a third transistor of the opposite conductivity type and having a base, an emitter and a collector; and a fourth resistor connected between the base of said first transistor and said collector of said third transistor; said emitter of said third transistor connected to said collector of said second transistor; and a fifth resistor connected between said comparator circuit output and said base of said third transistor.
Claim 8
Dependent Claim
290 words
A circuit for charging an input filter capacitance comprising: a source of potential having a battery terminal and a ground terminal; an input connected to said battery terminal, and an output; a first resistor and a second resistor connected in series between said input and said output; a first transistor of one conductivity type having a base, an emitter, and a collector, the emitter of said first transistor connected to the junction of said first and second resistors and the collector of said first transistor connected to said output; first diode means coupling said input to the base of said first transistor; a second transistor of the opposite conductivity type having a base, an emitter, and a collector, the emitter of said second transistor connected to said ground terminal; a series combination of a third resistor and second diode means connecting said output to the base of said second transistor; a third transistor of the same conductivity type as said first transistor and having a base, an emitter, and a collector, the emitter of said third transistor connected to the collector of said second transistor; a fourth resistor connected between the base of said first transistor and the collector of said third transistor; a comparator circuit having two input terminals and an output terminal, one of said input terminals connected to said input and the other of said input terminals connected to said output; a fifth resistor connected between said output terminal of said comparator circuit and the base of said third transistor; and a relay for bypassing the capacitance charging circuitry and comprising an operating coil connected between said output terminal of said comparator circuit and said ground terminal, and a contact connected between said input and said output.
Claim 9
Dependent Claim
290 words
A circuit for charging an input filter capacitance comprising: a source of potential having a battery terminal and a ground terminal; an input connected to said battery terminal, and an output; a first resistor and a second resistor connected in series between said input and said output; a first transistor of one conductivity type having a base, an emitter, and a collector, the emitter of said first transistor connected to the junction of said first and second resistors and the collector of said first transistor connected to said output; first diode means coupling said input to the base of said first transistor; a second transistor of the opposite conductivity type having a base, an emitter, and a collector, the emitter of said second transistor connected to said ground terminal; a series combination of a third resistor and second diode means connecting said output to the base of said second transistor; a third transistor of the same conductivity type as said first transistor and having a base, an emitter, and a collector, the emitter of said third transistor connected to the collector of said second transistor; a fourth resistor connected between the base of said first transistor and the collector of said third transistor; a comparator circuit having two input terminals and an output terminal, one of said input terminals connected to said input and the other of said input terminals connected to said output; a fifth resistor connected between said output terminal of said comparator circuit and the base of said third transistor; and a relay for bypassing the capacitance charging circuitry and comprising an operating coil connected between said output terminal of said comparator circuit and said ground terminal, and a contact connected between said input and said output.
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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) | 1980-06-20 | 1980-12-20 | 1981-06-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-06-20 | 1984-12-20 | 1985-06-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-06-20 | 1988-12-20 | 1989-06-21 | $7700.00 | Window Closed / Lapsed |