US4247849A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Constant current voltage sensing circuit
Assignee: BETA PRODUCTS Inc
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Filing: 1979-03-19
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Granted: 1981-01-27
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Expires: 1999-03-19
Abstract
Abstract A current limiting voltage sensing circuit especially suited as an annunciator input circuit is disclosed. It includes a radiation emitting device circuit, a current limiting circuit for maintaining the current supplied to the voltage sensing circuit at a substantially constant value while supplying the needed current to the radiation emitting device circuit, and a radiation sensitive device circuit coupled to the radiation emitting device and electrically isolated from it for converting from the radiation signal into an electrical signal. In one arrangement, the input to the voltage sensing circuit is a full-wave rectifier so that it can be used for detecting an ac voltage or a dc voltage in either direction. One arrangement of the current limiting circuit includes a field effect transistor with the drain-to-source forming a variable resistance current path for maintaining the current supplied to the voltage sensing circuit at a substantially constant value, and a circuit connecting the source of the field effect transistor in a feedback relationship to the gate. In one arrangement, the feedback circuit is a resistor in series with the radiation emitting device which is a light emitting diode. The radiation sensitive device in such an arrangement is a photodiode or phototransistor which forms an optical coupler with the light emitting diode.
Inventors
- 👤 Phillip D. Morris
- 👤 John H. Alford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 06:53
CPC Classifications
G; G01; G01R; G01R19/00; G01R19/165; G01R19/16504; G01R19/16519
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
222 words
A voltage sensing circuit comprising in combination: a radiation emitting device circuit including a device which emits radiation when current above a certain threshold level passes through it; an impedance circuit; an electronic device with at least a first terminal and a second terminal forming a current path therebetween in series with the impedance circuit and the radiation emitting device circuit, and a control terminal to control the effective resistance between the first terminal and the second terminal, and the control terminal is connected to a point on the side of the impedance circuit remote from the electronic device wherein the impedance circuit and the electronic device act together as a current limiting circuit for limiting the current supplied to the voltage sensing circuit to a substantially predetermined value and supplying current above the threshold level to the radiation emitting device when the voltage to be sensed is present across the series combination of radiation emitting device, impedance circuit and electronic device whereby a radiation signal is emitted from the radiation emitting device corresponding to the presence or absence of the voltage to be sensed; and a radiation sensitive device circuit coupled to the radiation emitting device and electrically isolated from the radiation emitting device circuit for converting from the radiation signal emitted from the radiation emitting device into an electrical signal.
Claim 2
Dependent Claim
222 words
A voltage sensing circuit comprising in combination: a radiation emitting device circuit including a device which emits radiation when current above a certain threshold level passes through it; an impedance circuit; an electronic device with at least a first terminal and a second terminal forming a current path therebetween in series with the impedance circuit and the radiation emitting device circuit, and a control terminal to control the effective resistance between the first terminal and the second terminal, and the control terminal is connected to a point on the side of the impedance circuit remote from the electronic device wherein the impedance circuit and the electronic device act together as a current limiting circuit for limiting the current supplied to the voltage sensing circuit to a substantially predetermined value and supplying current above the threshold level to the radiation emitting device when the voltage to be sensed is present across the series combination of radiation emitting device, impedance circuit and electronic device whereby a radiation signal is emitted from the radiation emitting device corresponding to the presence or absence of the voltage to be sensed; and a radiation sensitive device circuit coupled to the radiation emitting device and electrically isolated from the radiation emitting device circuit for converting from the radiation signal emitted from the radiation emitting device into an electrical signal.
Claim 3
Dependent Claim
53 words
A voltage sensing circuit according to claim 1 for sensing a voltage between two points further comprising a full-wave rectifier having a pair of input terminals for electrically connecting across the two points and a pair of output terminals connected across the circuit comprising the radiation emitting circuit and the current limiting circuit.
Claim 4
Dependent Claim
200 words
A voltage sensing circuit comprising in combination: a radiation emitting device circuit including a device which emits radiation when current above a certain threshold level passes through it; a field effect transistor with the drain to source forming a variable resistance current path in series with the radiation emitting device; a circuit electrically connecting the source of the field effect transistor in a feedback relationship to the gate of the field effect transistor, wherein the field effect transistor in combination with the circuit electrically connecting the source in a feedback relationship to the gate limits the current supplied to the voltage sensing circuit to a substantially predetermined value and supplies current above the threshold level to the radiation emitting device when the voltage to be sensed is present across the series combination of radiation emitting device and source to drain whereby a radiation signal is emitted from the radiation emitting device corresponding to the presence or absence of the voltage to be sensed; and a radiation sensitive device circuit coupled to the radiation emitting device and electrically isolated from the radiation emitting device circuit for converting from the radiation signal emitted from the radiation emitting device into an electrical signal.
Claim 5
Dependent Claim
200 words
A voltage sensing circuit comprising in combination: a radiation emitting device circuit including a device which emits radiation when current above a certain threshold level passes through it; a field effect transistor with the drain to source forming a variable resistance current path in series with the radiation emitting device; a circuit electrically connecting the source of the field effect transistor in a feedback relationship to the gate of the field effect transistor, wherein the field effect transistor in combination with the circuit electrically connecting the source in a feedback relationship to the gate limits the current supplied to the voltage sensing circuit to a substantially predetermined value and supplies current above the threshold level to the radiation emitting device when the voltage to be sensed is present across the series combination of radiation emitting device and source to drain whereby a radiation signal is emitted from the radiation emitting device corresponding to the presence or absence of the voltage to be sensed; and a radiation sensitive device circuit coupled to the radiation emitting device and electrically isolated from the radiation emitting device circuit for converting from the radiation signal emitted from the radiation emitting device into an electrical signal.
Claim 6
Dependent Claim
91 words
A voltage sensing circuit according to claim 3 for sensing a voltage wherein the circuit electrically connecting the source in a feedback relationship to the gate comprises a resistor, further comprising a full-wave rectifier having a pair of input terminals for electrically connecting across the source of the voltage to be sensed and a pair of output terminals with the positive output terminal connected to the drain side and the negative output terminal connected to the gate side of the circuit comprising the radiation emitting circuit and the current limiting circuit.
Claim 7
Dependent Claim
140 words
An annunciator input circuit for detecting a significant voltage across a pair of contacts, comprising in combination: a full-wave rectifier having a pair of input terminals for electrically connecting across the pair of contacts and a pair of output terminals, one of the output terminals being a positive terminal and one being a negative terminal; a field effect transistor having a drain connected to the positive terminal, a gate connected to the negative terminal, and a source; a resistor; a light emitting diode in series with the resistor, wherein the series combination of resistor and light emitting diode connects the source to the gate; and a photosensitive device circuit optically coupled to and electrically isolated from the light emitting diode for converting from the light signal emitted from the light emitting diode into an electrical signal acceptable by the annunciator.
Claim 8
Dependent Claim
140 words
An annunciator input circuit for detecting a significant voltage across a pair of contacts, comprising in combination: a full-wave rectifier having a pair of input terminals for electrically connecting across the pair of contacts and a pair of output terminals, one of the output terminals being a positive terminal and one being a negative terminal; a field effect transistor having a drain connected to the positive terminal, a gate connected to the negative terminal, and a source; a resistor; a light emitting diode in series with the resistor, wherein the series combination of resistor and light emitting diode connects the source to the gate; and a photosensitive device circuit optically coupled to and electrically isolated from the light emitting diode for converting from the light signal emitted from the light emitting diode into an electrical signal acceptable by the annunciator.
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) | 1984-01-27 | 1984-07-28 | 1985-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-27 | 1988-07-28 | 1989-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-27 | 1992-07-28 | 1993-01-27 | $7700.00 | Window Closed / Lapsed |