US3774186A - Smoke detector failure alarm - Google Patents

Smoke detector failure alarm Download PDF

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Publication number
US3774186A
US3774186A US00234775A US3774186DA US3774186A US 3774186 A US3774186 A US 3774186A US 00234775 A US00234775 A US 00234775A US 3774186D A US3774186D A US 3774186DA US 3774186 A US3774186 A US 3774186A
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circuit
alarm
instrument according
switch
capacitor
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Expired - Lifetime
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US00234775A
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English (en)
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R Enemark
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EL SIG LAB Inc
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EL SIG LAB Inc
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
    • G08B17/103—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device
    • G08B17/107—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device for detecting light-scattering due to smoke

Definitions

  • a regulated, half-wave rectifier supplies power for an exciter lamp, a photocell shielded from the lamp but viewing an area illuminated by the lamp, and a relay switching circuit triggered by the cell for applying the half-wave current to the winding of a horn so as to cause the horn to sound at the half-wave frequency when the cell senses smoke scattered from the illuminated area.
  • the switching circuit for the horn can also be triggered by a thermostatic switch responsive to high ambient temperature. Failure of the exciter lamp or voltage regulator deenergizes the relay, switching in a pulsing circuit which sounds the horn at a distinctively different frequency than the smoke alarm.
  • an instrument of the type described comprises an electrical alarm instrument for sensing aphysical condition comprising, an electrical alarm, a controlled switch in series with the alarm and having a control, a power supply connected to the alarm and switch, a condition responsive circuit connected to the switch control to close the switch and actuate the alarm in a mode dependent on the power supply, and pulsing means connected to the switch control for pulse storage and discharge to the switch control thereby to close the switch and actuate the alarm in a different mode dependent on the pulsing means, the responsive circuit including switching means responsive to failure in said circuit to render the pulsing means effective, whereby the alarm indicates light response and circuit failure differently.
  • FIGS. 1 and 2 of the accompanying drawing For the purpose of illustration typical smoke detector circuits are shown schematically in FIGS. 1 and 2 of the accompanying drawing.
  • the smoke detector circuit shown operates on 120 volt alternating current supplied to terminals A and C.
  • the alternating current is connected to a pair of arc suppressor diodes D3 (EDAL l 6SP5B5) with a peak to peak breakdown voltage of about 300 volts which shunt high voltage transients through a current limiting resistor R1 (4.7 ohms).
  • the transient-filtered current is half-wave rectified by a diode D 1 (1N4005).
  • the half-wave voltage excursion at the positive terminal of the diode D1 is limited by a transistor Q1 (Motorola MJ-400) whose base voltage is held at the approximately 105 volts breakdown point of a zener diode D2 in series with a voltage dividing resistor R2 between the positive halfwave supply and a ground bus G.
  • This regulated positive half-wave voltage is supplied through an exciter lamp DSl (Sylvania 60PSB) and a relay coil K in series, and also through a resistor R3 (33kilohms) to a pair of photocells PCI and PC2 (Clairex 5M7) in series with a resistor R6 (47 Kilohms).
  • a reverse-connected diode D4 (1N4005) parallels the relay coil, and a by-pass capacitor C2 (0.001 microfarad) parallels the second photocell PCZ.
  • the exciter lamp DSl illuminates an area, usually within a dark chamber through which air circulates.
  • the first photonated chamber Light from the illuminated area is scattered back to the photocell PC! only when smoke or like air. born particles enter the illuminated area.
  • the resistance and voltage drop across the first photocell PCl then falls from a high to a low value.
  • the second photocell PCZ is normally at a constant low light level, and hence its resistance is constant except for aging effects with constant light source.
  • the inductance L of the horn H produces a reactive current surge maintaining the SCR closed.
  • the thermostatic switch TH when closed by rise of ambient temperature, to say F, similarly raises the voltage at the SCR gate g sufficiently to close the SCR switch.
  • the relay contact K1 is transferred to the broken line position Kl In this position a diode D5 (lN4005) is connected to shunt the reactive surges of the horn coil L, and a pulsing network is connected through the coil to the positive supply.
  • the pulsing network comprises a storage capacitor C1 (0.1 microfarad) charged by current drawn through to horn coil L and a resistor R7 (10 megohms).
  • the time constant of resistor R5 and capacitor C1 controls the rate of charge of the capacitor C1 to the approximately 65 volt firing potential of a second neon glow discharge lamp Ne2 such that firing potential occurs about twice a second. Firing of the second neon lamp Ne2 discharges capacitor C1 through a resistor R5 1 kilohm) and applies a closing pulse of voltage to the gate 3 of the SCR switch Q2, drawing current through the horn coil L for one half-wave or less of the supply current.
  • the SCR switch opens and in succeeding rectified half-wave cycles the capacitor C1 recharges.
  • the 2 cycle per second rate at which the pulsing circuit draws current through the horn causes the horn to click at the slow 2 c.p.s. rate. This slow rate is distinctly different from the 60 c.p.s. steady sound emitted when the horn continuously draws the half-wave rectified current.
  • FIG. 2 Shown in FIG. 2 is a smoke detector circuit similar to that of FIG. 1 but provided with an electronic relay circuit in lieu of the mechanical relay circuit of FIG. 1. Also added is a 22 megohm resistor in parallel with photocell PC2. Like numbered components are identical in FIGS. 1 and 2.
  • the circuit of FIG. 2 actuates the pulsing circuit C], R5, R7, N62 if the lamp Dsi opens.
  • a transistor ()3 is connected in parallel with the lamp by a coupling resistor R8 (47 kilohms) and is normally held conducting with lamp current through a resistor R4 (270 ohms) coupled by a resistor R9 (2.7 kilohms) to its base.
  • the tendency of the horn inductance L to keep the SCR Q2 latched through a full cycle is accompanied by the tendency of the anode of diode D5 to become positive with respect tocapacitor C4. in this case the diode D5 conducts current through the resistor R10 whose voltage drop triggers a second SCR O4 to conduction allowing the SCR Q4 and the diode D5 to shunt the inductive surge of the horn coil L.
  • An electrical alarm instrument for sensing a physical condition comprising,
  • condition responsive circuit connected to the switch control to close the switch and actuate the alarm in a mode dependent on the power supply
  • pulsing means connected between the power supply and the switch control for pulse storage from said common power supply and discharge to the switch control thereby to close the switch and actuate the alarm in a different mode dependent on the pulsing means
  • the responsive circuit including coupling means connected between the condition responsive circuit and pulsing means responsive to failure in said circuit to render the pulsing means effective
  • said pulsing means comprises a resistor-and capacitor having a characteristic time constant.
  • said pulsing means comprises a breakdown device connecting said capacitor and switch control when the capacitor is charged to a predetermined voltage effective to open the switch.
  • said pulsing means comprises a resistor and capacitor having a characteristic time constant.
  • said alarm comprises an inductance reacting to each unrectified half cycle to maintain power through the controlled switch during unrectified half cycles.
  • An instrument according to claim 8 characterized by a unidirectional conducting device connected between the power supply and said capacitor, the switching means of said photo-responsive circuit being effective on circuit failure to connect said device in shunt with the alarm inductance and prevent the inductance from maintaining power through the controlled switch.
  • said alarm comprises an inductance reacting to each unrectified half cycle to maintain power through the controlled switch during unrectified half cycles, characterized by a unidirectional conducting device, said relay contact connecting said device in shunt with the alarm inductance upon circuit failure.
  • said photosensitive device comprises a photocell shielded from the exciter lamp and viewing an area illuminated by the lamp, whereby to respond to light scattered by fluid born particles in the illuminated area.
  • a smoke detector for operation on alternating current comprising,
  • the power supply including a half-wave rectifier of the alternating current connected to the positive and negative busses, and voltage regulator means connected to the busses,
  • the smoke sensing circuit including an exciter lamp and a relay connected to the busses, and a photocell connected to the busses, the cell being shielded from the exciter lamp and viewing the area illuminated by the lamp;
  • the alarm circuit including an inductive signaling device in series with a controlled rectifier and connected to said busses, the gate of said controlled rectifier being connected to the photocell and responsive thereto to complete a circuit through the signalling device, and
  • the failure sub-circuit comprising a diode, a resistance and a capacitor in series between the busses, the resistance and capacitor having a time constant substantially greater than the current alterations, a gas discharge breakdown device to the junction of the resistance and capacitor and to the controlled rectifier gate, and the relay contact having a position connecting the inductive signalling device to the capacitor and connecting the diode in shunt with the inductive signalling device.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fire-Detection Mechanisms (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Emergency Alarm Devices (AREA)
US00234775A 1972-03-15 1972-03-15 Smoke detector failure alarm Expired - Lifetime US3774186A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US23477572A 1972-03-15 1972-03-15

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US3774186A true US3774186A (en) 1973-11-20

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US00234775A Expired - Lifetime US3774186A (en) 1972-03-15 1972-03-15 Smoke detector failure alarm

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US (1) US3774186A (de)
CA (1) CA981754A (de)
DE (1) DE2312977A1 (de)
GB (1) GB1394642A (de)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3879717A (en) * 1974-06-19 1975-04-22 K F Ind Inc Portable methane monitor and alarm system
US3936814A (en) * 1974-04-29 1976-02-03 Bernz-O-Matic Corporation Smoke detector and alarm
US3980997A (en) * 1974-07-17 1976-09-14 General Signal Corporation Smoke detector
US4001800A (en) * 1974-06-24 1977-01-04 Gentex Company Smoke detecting device
US4021792A (en) * 1975-06-23 1977-05-03 Wellen Industries Smoke alarm
US4093943A (en) * 1976-12-27 1978-06-06 Knight Webster B Sequential power distribution circuit
US4096473A (en) * 1976-12-09 1978-06-20 P.R. Mallory & Co. Inc. High output smoke and heat detector alarm system utilizing a piezoelectric transducer and a voltage doubling means
US4101880A (en) * 1976-12-27 1978-07-18 Wheelock Signals, Inc. Audiovisual signaling device
US4266220A (en) * 1979-07-27 1981-05-05 Malinowski William J Self-calibrating smoke detector and method
USRE30620E (en) * 1978-07-03 1981-05-19 P. R. Mallory & Co. Inc. High output smoke and heat detector alarm system utilizing a piezoelectric transducer and a voltage doubling means
US4283657A (en) * 1976-03-25 1981-08-11 Lampiridae Associates Exit illuminating system
US4302753A (en) * 1978-01-26 1981-11-24 Pittway Corporation Multi-function combustion detecting device
US4471346A (en) * 1981-06-02 1984-09-11 Eberhard Faber, Inc. Smoke detector

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3446649A (en) * 1963-09-05 1969-05-27 Azoplate Corp Developing electrostatic images with a liquid developer
US3487404A (en) * 1967-03-23 1969-12-30 Avco Corp Combined fire alarm,burglar alarm,and intercommunication system
US3555532A (en) * 1968-10-29 1971-01-12 Graham Stuart Corp Vapor or particle detection device
US3693110A (en) * 1971-02-23 1972-09-19 C A Briggs Co Audible signal or alarm device including two variable frequency unijunction transistor oscillators

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3446649A (en) * 1963-09-05 1969-05-27 Azoplate Corp Developing electrostatic images with a liquid developer
US3487404A (en) * 1967-03-23 1969-12-30 Avco Corp Combined fire alarm,burglar alarm,and intercommunication system
US3555532A (en) * 1968-10-29 1971-01-12 Graham Stuart Corp Vapor or particle detection device
US3693110A (en) * 1971-02-23 1972-09-19 C A Briggs Co Audible signal or alarm device including two variable frequency unijunction transistor oscillators

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3936814A (en) * 1974-04-29 1976-02-03 Bernz-O-Matic Corporation Smoke detector and alarm
US3879717A (en) * 1974-06-19 1975-04-22 K F Ind Inc Portable methane monitor and alarm system
US4001800A (en) * 1974-06-24 1977-01-04 Gentex Company Smoke detecting device
US3980997A (en) * 1974-07-17 1976-09-14 General Signal Corporation Smoke detector
US4021792A (en) * 1975-06-23 1977-05-03 Wellen Industries Smoke alarm
US4283657A (en) * 1976-03-25 1981-08-11 Lampiridae Associates Exit illuminating system
US4096473A (en) * 1976-12-09 1978-06-20 P.R. Mallory & Co. Inc. High output smoke and heat detector alarm system utilizing a piezoelectric transducer and a voltage doubling means
US4101880A (en) * 1976-12-27 1978-07-18 Wheelock Signals, Inc. Audiovisual signaling device
US4093943A (en) * 1976-12-27 1978-06-06 Knight Webster B Sequential power distribution circuit
US4302753A (en) * 1978-01-26 1981-11-24 Pittway Corporation Multi-function combustion detecting device
USRE30620E (en) * 1978-07-03 1981-05-19 P. R. Mallory & Co. Inc. High output smoke and heat detector alarm system utilizing a piezoelectric transducer and a voltage doubling means
US4266220A (en) * 1979-07-27 1981-05-05 Malinowski William J Self-calibrating smoke detector and method
US4471346A (en) * 1981-06-02 1984-09-11 Eberhard Faber, Inc. Smoke detector

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Publication number Publication date
DE2312977A1 (de) 1973-09-27
GB1394642A (en) 1975-05-21
CA981754A (en) 1976-01-13

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