US3684896A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flasher circuit with short protection
Assignee: Meridian Industries Inc
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Filing: 1970-08-26
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Granted: 1972-08-15
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Expires: 1990-08-26
Abstract
Abstract A flasher circuit has a power transistor controlling a circuit with a load therein; a multivibrator produces a timed pulse signal applied to the power transistor for turning the power transistor ''''on;'''' and additional voltage sensing means operatively coupled to the load or power transistor and sensitive to the voltage drop across the emitter base diode thereof due to the occurrence of a short is effective to cause said power transistor to become non-conductive when said voltage drop exceeds a predetermined value.
Inventors
- 👤 John F Bolinger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 01:59
CPC Classifications
H; H05; H05B; H05B39/00; H05B39/09; H02; H02H; H02H7/00; H02H7/20
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
322 words
A flasher circuit for vehicle lamps adapted to alternately connect and disconnect a voltage source and a lamp load, said flasher comprising a load switching transistor having an input circuit extending between its emitter and base and an output circuit with the output circuit extending between its emitter and collector and being adapted to connect the lamp load with the voltage source, an oscillator adapted to produce control signal impulses, a transistor amplifying means having its input circuit connected with the output circuit of said oscillator and having its output circuit connected with the input circuit of said load switching transistor whereby said load switching transistor is switched between on and off conditions in response to the control signal impulses, voltage responsive means including a control transistor having an input circuit extending between its emitter and base and an output circuit extending between its emitter and collector and including a voltage reference device, the input circuit of the control transistor being connected across the emitter and base of the load switching transistor in series circuit with said voltage reference device, the emitter and base of the control transistor being poled oppositely from the emitter and base of the switching transistor in said series circuit whereby the output circuit of said control transistor becomes conductive when the voltage across the emitter and base of the load switching transistor exceeds a value determined by said voltage reference device, semiconductor switching means having an output circuit connected across the input circuit of said transistor amplifying means and having an input circuit connected with the output circuit of the control transistor whereby said semiconductor switching means becomes conductive and disables the transistor amplifying means to prevent application of the control signal impulses to the input circuit of the load switching transistor when a short circuit across said lamp load causes the voltage across the input circuit of the load switching transistor to exceed said predetermined value.
Claim 2
Dependent Claim
322 words
A flasher circuit for vehicle lamps adapted to alternately connect and disconnect a voltage source and a lamp load, said flasher comprising a load switching transistor having an input circuit extending between its emitter and base and an output circuit with the output circuit extending between its emitter and collector and being adapted to connect the lamp load with the voltage source, an oscillator adapted to produce control signal impulses, a transistor amplifying means having its input circuit connected with the output circuit of said oscillator and having its output circuit connected with the input circuit of said load switching transistor whereby said load switching transistor is switched between on and off conditions in response to the control signal impulses, voltage responsive means including a control transistor having an input circuit extending between its emitter and base and an output circuit extending between its emitter and collector and including a voltage reference device, the input circuit of the control transistor being connected across the emitter and base of the load switching transistor in series circuit with said voltage reference device, the emitter and base of the control transistor being poled oppositely from the emitter and base of the switching transistor in said series circuit whereby the output circuit of said control transistor becomes conductive when the voltage across the emitter and base of the load switching transistor exceeds a value determined by said voltage reference device, semiconductor switching means having an output circuit connected across the input circuit of said transistor amplifying means and having an input circuit connected with the output circuit of the control transistor whereby said semiconductor switching means becomes conductive and disables the transistor amplifying means to prevent application of the control signal impulses to the input circuit of the load switching transistor when a short circuit across said lamp load causes the voltage across the input circuit of the load switching transistor to exceed said predetermined value.
Claim 3
Dependent Claim
17 words
A flasher circuit as defined in claim 1 wherein said reference voltage device comprises a Zener diode.
Claim 4
Dependent Claim
16 words
The invention as defined in claim 1 wherein said reference voltage device comprises voltage divider resistors.
Claim 5
Dependent Claim
47 words
The invention as defined in claim 1 wherein said semiconductor switching means comprises a silicon controlled rectifier having its anode and cathode connected across the input circuit of the transistor amplifying means and having its cathode and gate connected across the output circuit of said control transistor.
Claim 6
Dependent Claim
48 words
The invention as defined in claim 4 and further including a second Zener diode adapted to be connected across said voltage source through the gate and cathode of the silicon controlled rectifier whereby said transistor amplifying means is disabled in response to excessive voltage from said voltage source.
Claim 7
Dependent Claim
50 words
The invention as defined in claim 1 and further including a capacitor connected across the input circuit of said control transistor to delay the turn-on of said transistor and thus avoid unwanted switching of said load switching transistor in response to initial in-rush current when the lamp load is cold.
Claim 8
Dependent Claim
66 words
The invention as defined in claim 4 wherein a semiconductor diode is connected in series with the input circuit of said transistor amplifying means and poled for conduction in the same direction as said input circuit whereby the voltage drop across the anode-cathode of said silicon controlled rectifier when the same is conductive in insufficient to cause conduction through the input circuit of said amplifying means.
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) | 1975-08-15 | 1976-02-14 | 1976-08-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-15 | 1980-02-14 | 1980-08-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-15 | 1984-02-14 | 1984-08-15 | $7700.00 | Window Closed / Lapsed |