US3857062A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flashing lamp circuits
Assignee: CAV Ltd
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Filing: 1973-08-27
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Granted: 1974-12-24
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Expires: 1993-08-27
Abstract
Abstract A flashing lamp circuit for flashing a lamp includes intermittently operable switch means connected in series with a resistor with the lamp to be flashed, voltage sensing means including a transistor for detecting the voltage across the resistor when the lamp is illuminated, said voltage sensing means including a capacitor which is charged in the event that the voltage across the resistor is below a predetermined value when the switch means is closed. A transistor switch including transistors controls the operation of a warning lamp and when the switch means is open the warning lamp will be illuminated. In the event that the capacitor has been charged, the transistor switch will be rendered non-conductive and the warning lamp will remain in an extinguished condition.
Inventors
- 👤 G Leonard
- 👤 A Ramshaw
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:12
CPC Classifications
H; H05; H05B; H05B39/00; H05B39/09
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
170 words
A flashing lamp circuit comprising a pair of supply terminals, contact means connected in series with the lamp to be flashed, a resistor connected in series with said lamp and across which when said contact means is closed is developed a voltage indicative of the current flow through said lamp, a warning lamp, a transistor switch including a transistor having its collector emitter path connected in series with said warning lamp across said contact means, said transistor switch being operable to cause illumination of said warning lamp when said contact means is open, voltage sensing means for sensing the voltage developed across said resistor, a capacitor associated with said voltage sensing Means, said voltage sensing means establishing a charging path for said capacitor in the event that the voltage across said resistor falls below a predetermined value when the contact means is closed, the voltage across said capacitor acting to prevent conduction of said transistor when said contact means is next opened and thereby preventing illumination of the warning lamp.
Claim 2
Dependent Claim
170 words
A flashing lamp circuit comprising a pair of supply terminals, contact means connected in series with the lamp to be flashed, a resistor connected in series with said lamp and across which when said contact means is closed is developed a voltage indicative of the current flow through said lamp, a warning lamp, a transistor switch including a transistor having its collector emitter path connected in series with said warning lamp across said contact means, said transistor switch being operable to cause illumination of said warning lamp when said contact means is open, voltage sensing means for sensing the voltage developed across said resistor, a capacitor associated with said voltage sensing Means, said voltage sensing means establishing a charging path for said capacitor in the event that the voltage across said resistor falls below a predetermined value when the contact means is closed, the voltage across said capacitor acting to prevent conduction of said transistor when said contact means is next opened and thereby preventing illumination of the warning lamp.
Claim 3
Dependent Claim
102 words
A circuit as claimed in claim 1 in which said voltage sensing means includes a further transistor having its base connected to a potentiometer chain which ensures that the base potential is a fixed proportion of the voltage across said supply terminals when said switch means is closed, the emitter collector path of said further transistor being connected in series with said resistor and with a further resistor across said supply terminals when said contact means is closed, said capacitor being connected in parallel with said further resistor, so that the capacitor is charged only when said further transistor is rendered conductive.
Claim 4
Dependent Claim
17 words
A circuit as claimed in claim 2 including a diode interconnecting the capacitor and said transistor switch.
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) | 1977-12-23 | 1978-06-24 | 1978-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-23 | 1982-06-24 | 1982-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-23 | 1986-06-24 | 1986-12-24 | $7700.00 | Window Closed / Lapsed |