Patent US3766433A successfully refreshed from Google Patents.
US3766433A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Crowbar circuit responsive to decrease in the power supply
Assignee: Bull HN Information Systems Italia SpA
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Filing: 1972-05-01
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Granted: 1973-10-16
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Expires: 1992-05-01
Abstract
Abstract A unijunction transistor, a capacitor, a transformer, an SCR and resistors provide an inexpensive crowbar circuit for use with a switching regulator. The crowbar circuit causes a voltage from the switching regulator to drop rapidly when the switching regulator is turned off.
Inventors
- 👤 J Nowell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 14:10
CPC Classifications
G; G11; G11C; G11C11/00; G11C11/02; G11C11/06; G11C11/06007; H; H02; H02H; H02H3/00; H02H3/24
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
233 words
A crowbar circuit for causing the voltage at the output terminal of a power supply to decrease rapidly when power to the input terminals of the supply is turned off, said circuit comprising: a source of potential, said source providing first and second reference potentials, said source being coupled to said input terminals of said supply; a unijunction transistor having first and second bases and an emitter, said first potential being connected to said second base of said transistor; first and second resistors, said first resistor being connected between said first potential and said emitter of said transistor, said second resistor being connected between said second potential and said emitter of said transistor; a capacitor, said capacitor being connected between said second potential and said emitter of said transistor; and a semiconductor device having first and second output electrodes and a gate electrode, said first output electrode of said device being connected to said output terminal of said supply, said second output electrode of said device being connected to said second potential, said gate electrode of said device being coupled to said first base of said transistor wherein said capacitor holds the voltage supplied to the emitter of said transistor in a steady state for a period of time necessary for said transistor and said device to be rendered conductive upon the decrease in voltage at the input terminals of the power supply.
Claim 2
Dependent Claim
233 words
A crowbar circuit for causing the voltage at the output terminal of a power supply to decrease rapidly when power to the input terminals of the supply is turned off, said circuit comprising: a source of potential, said source providing first and second reference potentials, said source being coupled to said input terminals of said supply; a unijunction transistor having first and second bases and an emitter, said first potential being connected to said second base of said transistor; first and second resistors, said first resistor being connected between said first potential and said emitter of said transistor, said second resistor being connected between said second potential and said emitter of said transistor; a capacitor, said capacitor being connected between said second potential and said emitter of said transistor; and a semiconductor device having first and second output electrodes and a gate electrode, said first output electrode of said device being connected to said output terminal of said supply, said second output electrode of said device being connected to said second potential, said gate electrode of said device being coupled to said first base of said transistor wherein said capacitor holds the voltage supplied to the emitter of said transistor in a steady state for a period of time necessary for said transistor and said device to be rendered conductive upon the decrease in voltage at the input terminals of the power supply.
Claim 3
Dependent Claim
57 words
A crowbar circuit as defined in claim 1 including: a transformer having a primary winding and a secondary winding, said primary winding of said transformer being connected between said second potential and said first base of said transistor, said secondary winding of said transformer being connected between said second potential and said gate electrode of said device.
Claim 4
Dependent Claim
78 words
A crowbar circuit as defined in claim 1 including: a third resistor; and a transformer having a primary winding and a secondary winding, said primary winding of said transformer being connected between said second potential and a first end of said third resistor, a second end of said third resistor being connected to said first base of said transistor, said secondary winding of said transformer being connected between said second potential and said gate electrode of said device.
Claim 5
Dependent Claim
227 words
A crowbar circuit for causing the voltage at the output terminal of a power supply to decrease rapidly when power to the input terminals of the supply is turned off, said circuit comprising: a source of potential, said source providing first and second reference potentials, said source being coupled to said input terminals of said supply; a unijunction transistor having first and second bases and an emitter, said first potential being connected to said second Base of said transistor; first and second resistors, said first resistor being connected between said first potential and said emitter of said transistor, said second resistor being connected between said second potential and said emitter of said transistor; a capacitor, said capacitor being connected between said second potential and said emitter of said transistor; and a silicon controlled rectifier having an anode, a cathode and a gate, said anode of said rectifier being connected to said output terminal of said supply, said cathode of said rectifier being connected to said second potential, said gate of said rectifier being coupled to said first base of said transistor wherein said capacitor holds the voltage applied to the emitter of said transistor in a steady state for a period of time necessary for said transistor and said rectifier to be rendered conductive upon the decrease in voltage at the input terminals of the power supply.
Claim 6
Dependent Claim
227 words
A crowbar circuit for causing the voltage at the output terminal of a power supply to decrease rapidly when power to the input terminals of the supply is turned off, said circuit comprising: a source of potential, said source providing first and second reference potentials, said source being coupled to said input terminals of said supply; a unijunction transistor having first and second bases and an emitter, said first potential being connected to said second Base of said transistor; first and second resistors, said first resistor being connected between said first potential and said emitter of said transistor, said second resistor being connected between said second potential and said emitter of said transistor; a capacitor, said capacitor being connected between said second potential and said emitter of said transistor; and a silicon controlled rectifier having an anode, a cathode and a gate, said anode of said rectifier being connected to said output terminal of said supply, said cathode of said rectifier being connected to said second potential, said gate of said rectifier being coupled to said first base of said transistor wherein said capacitor holds the voltage applied to the emitter of said transistor in a steady state for a period of time necessary for said transistor and said rectifier to be rendered conductive upon the decrease in voltage at the input terminals of the power supply.
Claim 7
Dependent Claim
56 words
A crowbar circuit as defined in claim 4 including: a transformer having a primary winding and a secondary winding, said primary winding of said transformer being connected between said second potential and said first base of said transistor, said secondary winding of said transformer being connected between said second potential and said gate of said rectifier.
Claim 8
Dependent Claim
77 words
A crowbar circuit as defined in claim 4 including: a third resistor; and a transformer having a primary winding and a secondary winding, said primary winding of said transformer being connected between said second potential and a first end of said third resistor, a second end of said third resistor being connected to said first base of said transistor, said secondary winding of said transformer being connected between said second potential and said gate of said rectifier.
References Cited (Backward Citations)
US3538383A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-15 | 1977-04-16 | 1977-10-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-15 | 1981-04-16 | 1981-10-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-15 | 1985-04-16 | 1985-10-16 | $7700.00 | Window Closed / Lapsed |