US3916262A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low voltage bus-operated overvoltage protection system
Assignee: United States Department of the Navy
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Filing: 1974-07-23
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Granted: 1975-10-28
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Expires: 1994-07-23
Abstract
Abstract An overvoltage protection circuit compares a bus voltage to a reference voltage developed from the bus and produces and output signal initiating appropriate action when the bus threshold levels established by the reference are exceeded. Since the circuit is powered directly from the bus, it does not require an independent power supply. Instead, the combination of a constant current source and a compensated voltage network convert the fluctuating bus voltage into a stabilized reference voltage. The reference voltage is then compared to the bus voltage by differential amplifier means.
Inventors
- 👤 Finis C Easter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:00
CPC Classifications
H; H02; H02H; H02H3/00; H02H3/20; H02H3/02; H02H3/05
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
99 words
An overvoltage protection circuit for monitoring the voltage at a bus comprising: constant current source powered directly from said bus voltage for generating a constant current output; compensated voltage means for establishing a stabilized voltage reference from said constant current output; first differential amplifier for comparing a first voltage derived from said reference to said bus voltage and conducting an output whenever said bus voltage exceeds said first voltage; and second differential amplifier for comparing a second different voltage derived from said reference to said bus voltages and conducting an output whenever said bus voltage exceeds said second voltage.
Claim 2
Dependent Claim
99 words
An overvoltage protection circuit for monitoring the voltage at a bus comprising: constant current source powered directly from said bus voltage for generating a constant current output; compensated voltage means for establishing a stabilized voltage reference from said constant current output; first differential amplifier for comparing a first voltage derived from said reference to said bus voltage and conducting an output whenever said bus voltage exceeds said first voltage; and second differential amplifier for comparing a second different voltage derived from said reference to said bus voltages and conducting an output whenever said bus voltage exceeds said second voltage.
Claim 3
Dependent Claim
54 words
The overvoltage protection circuit of claim 1 wherein said constant current source comprises a diode and transistor combination, said diode being driven directly said bus voltage and establishing a constant voltage drop across the base to emitter junction of said transistor, the collector of said transistor conducting a constant current output in response thereto.
Claim 4
Dependent Claim
73 words
The overvoltage protection circuit of claim 2 wherein said compensated voltage means comprises a zener diode connected to oppose the current from said collector of said transistor thus establishing a constant voltage across said zener diode, said constant directly zener voltage being connected in parallel across a forward bias diode and a plurality of resistive elements to establish different voltage reference levels, said forward bias diode providing temperature compensation for said zener diode.
Claim 5
Dependent Claim
136 words
In an overvoltage protection circuit including a zener diode and a forward bias diode in parallel therewith, a method of protecting a bus to which a voltage is applied comprising the steps of: generating a constant current from said bus voltage; opposing the flow of said constant current by said zener diode to establish a relatively constant voltage; utilizing said forward bias diode to compensate for temperature changes in said zener diode, said forward bias diode having a temperature coefficient in approximately the same range as said zener diode, thus providing a stabilized compensated voltage; deriving at least one reference voltage from said compensated voltage which is representative of an overvoltage level; comparing said bus voltage with each said reference voltage; and causing an output to be produced when said bus voltage exceeds said reference voltage.
Claim 6
Dependent Claim
136 words
In an overvoltage protection circuit including a zener diode and a forward bias diode in parallel therewith, a method of protecting a bus to which a voltage is applied comprising the steps of: generating a constant current from said bus voltage; opposing the flow of said constant current by said zener diode to establish a relatively constant voltage; utilizing said forward bias diode to compensate for temperature changes in said zener diode, said forward bias diode having a temperature coefficient in approximately the same range as said zener diode, thus providing a stabilized compensated voltage; deriving at least one reference voltage from said compensated voltage which is representative of an overvoltage level; comparing said bus voltage with each said reference voltage; and causing an output to be produced when said bus voltage exceeds said reference voltage.
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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) | 1978-10-27 | 1979-04-28 | 1979-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-27 | 1983-04-28 | 1983-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-27 | 1987-04-28 | 1987-10-28 | $7700.00 | Window Closed / Lapsed |