US3733595A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Condition responsive switching circuit
Assignee: Individual
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Filing: 1971-02-12
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Granted: 1973-05-15
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Expires: 1991-02-12
Abstract
Abstract A circuit which actuates a visible or audible alarm in response to the reception of dangerous fluids such as smoke, fumes, or gas. The circuit includes a sensor which changes internal resistance when the fluid to be detected is present in the environment surrounding the sensor. The change of the sensor actuates a switching or trigger circuit which results in the sounding of an audible alarm or the lighting of a visual alarm or both. A delay circuit which maintains the sensor circuitry in an unenergized condition until the system stabilizes after power is first applied is also provided to prevent spurious alarms.
Inventors
- 👤 E Benedict
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 12:43
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/117
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
275 words
A system for giving an alarm in the presence of invisible and odorless gases comprising: a transformer including a primary winding, a low voltage winding and an intermediate voltage winding, a first resistor connected to said primary winding, a first lamp connected to said first resistor and said primary winding, said first resistor and said first lamp forming a series circuit in shunt with said primary winding for indicating the application of electrical power to said system, a gas detector connected to said transformer, said gas detector including a resistance means which changes its electrical resistance when subjected to a predetermined gas, a voltage divider in series with said gas detector resistance means, a control transistor including collector, emitter, and base electrodes, said emitter electrode connected to said primary winding, a second resistor connected between said base electrode and said emitter electrode, a diode connected between said voltage divider and said base electrode and poled to render said transistor conductive when the voltage developed on said voltage divider reaches a predetermined value, an alarm activating means, a first switching means for controlling current flow through said alarm activating means, a voltage rectifier connected to said transformer, a current flow responsive means connected between said voltage rectifier and said collector electrode for controlling said first switching means, a second switching means connected between said voltage rectifier and said collector electrode for completing a series circuit comprised of said second switching means, said current flow responsive means and said control transistor, and a resistive and capacitive time delay network connected to said transformer for closing said second switching means when said capacitance reaches a predetermined charge level.
Claim 2
Independent Claim
275 words
A system for giving an alarm in the presence of invisible and odorless gases comprising: a transformer including a primary winding, a low voltage winding and an intermediate voltage winding, a first resistor connected to said primary winding, a first lamp connected to said first resistor and said primary winding, said first resistor and said first lamp forming a series circuit in shunt with said primary winding for indicating the application of electrical power to said system, a gas detector connected to said transformer, said gas detector including a resistance means which changes its electrical resistance when subjected to a predetermined gas, a voltage divider in series with said gas detector resistance means, a control transistor including collector, emitter, and base electrodes, said emitter electrode connected to said primary winding, a second resistor connected between said base electrode and said emitter electrode, a diode connected between said voltage divider and said base electrode and poled to render said transistor conductive when the voltage developed on said voltage divider reaches a predetermined value, an alarm activating means, a first switching means for controlling current flow through said alarm activating means, a voltage rectifier connected to said transformer, a current flow responsive means connected between said voltage rectifier and said collector electrode for controlling said first switching means, a second switching means connected between said voltage rectifier and said collector electrode for completing a series circuit comprised of said second switching means, said current flow responsive means and said control transistor, and a resistive and capacitive time delay network connected to said transformer for closing said second switching means when said capacitance reaches a predetermined charge level.
Claim 3
Dependent Claim
33 words
The system of claim 1 wherein said voltage rectifier includes a full wave rectifier bridge network and said resistive and capacitive time delay network is connected across said full wave rectifier bridge network.
Claim 4
Dependent Claim
158 words
The system of claim 1 wherein said second switching means includes: a first transistor including collector, base and emitter electrodes, said first transistor base electrode connected to said resistive and capacitive time delay network, a second transistor including collector, base and emitter electrodes, said second transistor base electrode connected to said first transistor emitter electrode, said second transistor emitter electrode connected to said full wave rectifier bridge network, said second transistor collector electrode connected to said first transistor collector electrode, a first relay including a coil and first and second sets of normally open relay contacts, said first relay coil connected between said first and second transistor collector electrode and said full wave rectifier bridge network, said first relay first set of normally open contacts interposed between said first resistor and said primary winding connection, and said first relay second set of normally open contacts connected between said current flow responsive means and said control transistor collector electrode.
Claim 5
Dependent Claim
47 words
The system of claim 3 wherein said current flow responsive means includes: a second relay including a coil connected between said first relay second set of contacts and said full wave rectifier bridge network and a set of normally open contacts connected as said first switching means.
Claim 6
Dependent Claim
28 words
The system of claim 1 wherein said second switching means includes: a siLicon controlled rectifier including a control electrode connected to said resistive and capacitive time delay network.
Claim 7
Dependent Claim
24 words
The system of claim 5 further including an indicator lamp interposed between said control electrode connection to said resistive and capacitive time delay network.
Claim 8
Dependent Claim
42 words
The system of claim 6 wherein said current flow responsive means includes: a relay including a coil connected between said silicon controlled rectifier and said control transistor collector electrode and a set of normally open contacts connected as said first switching means.
Claim 9
Dependent Claim
27 words
The system of claim 7 further including: a variable resistance means interposed between said diode connection to said voltage divider for controlling the sensitivity of said system.
Claim 10
Dependent Claim
16 words
The system of claim 8 wherein said first lamp and said indicator lamp are neon bulbs.
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) | 1976-05-14 | 1976-11-13 | 1977-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-14 | 1980-11-13 | 1981-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-14 | 1984-11-13 | 1985-05-15 | $7700.00 | Window Closed / Lapsed |