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Publication numberUS3603973 A
Publication typeGrant
Publication dateSep 7, 1971
Filing dateApr 11, 1968
Priority dateApr 11, 1968
Publication numberUS 3603973 A, US 3603973A, US-A-3603973, US3603973 A, US3603973A
InventorsHough Howard O
Original AssigneeHough Howard O
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Combination fire and burglar alarm system
US 3603973 A
Abstract  available in
Images(3)
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Claims  available in
Description  (OCR text may contain errors)

United States Patent Inventor "ward s 2,895,125 7/1959 Watts 340/409 x 6 sqliml Hill y 2,971,184 2 1961 Pearson eta]. 340/258 c 01778 3,049,623 8/1962 Du Vall 307/66 pp 720,587 3,189,788 6/1965 Cady 307/66x Filed p 1,1968 3,230,518 l/1966 Vassil etal 340/258 C 1 Patented p 3,418,487 12/1968 Livingston i 307/66 2,041,540 /1936 Goldstone 340/333 3,257 l 1961 H 340 333 541 gowns/mos mu: AND BURGLAR ALARM gg 416 131962 321;," 3401333 YSTEM 6 Cum, 3 Drum! Figs- 3,174,143 3/1965 Ak1n 340/409 X Primary Examiner-John W. Caldwell [52] 0.8. CI. 340/409,

307/66, 340/227, 340/276, 340/333, 340/420 :fjf' Pam'dge 511 1m. 01. ..G08b 19/00,

G08b 29/00, H02j 9/00 [50] Field of Search 340/333, ABSTRACT; A fi and burglar alarm system f r idi 409, 227, 276,228,420, 258 C; 307/66 automatic detection of a fire or burglary having active and passive components which are capable of operating at very [56] lacuna CM low power levels continuously until the components are called UNITED STATES PATENTS upon to indicate a fire or burglary. The system is provided 2,492,432 l2/l949 Laford 340/276 with alternate sources of power to insure the reliability of 1 52 F r flt l'u- 3 /276 UX operation. Supervisory circuitry is provided for giving visual 2,605,342 7/1952 Spurling 340/276 UX indication that all sensors and circuitry are in proper operating 2,701,874 2/1955 M6818 /27 conditions. Annunciator circuitry is also provided to give .3 /1 56 33110 34 /276 X visual indication of exact location or zone of conflagration.

17 19 a1 24 131 ll I I H It srznnmm azcnnza AC 22 "mans. 28:8" T554 T "8- J 1.00m.

l L 1 l III= 1 J| f 2a RELAY CIRCUIT BATTERY BATTERY F "32$?" filkauli 63.4% I DETECTOR I I CIRCUIT F l l STAND IV 29 ZONE 0 :15:: ANNUNCIATOR POWER {33 9| (43 BATTERY PROTECTION nr'rsnv l A1 15: l. 26 cmcurr RELAY -'\N\v L225 32?" 137 45 BURGLER l|33 A 28814? ensures PATENIEDsEP 1m:

SHEET 2 [IF 3 INVENTOR TTORNEY COMBINATION FIRE AND BURGLAR ALARM SYSTEM The present invention relates to alarm systems and, more particularly, to an alarm system for indicating a fire or burglary.

An object of the invention is to provide a fire and burglar alarm system which will not be activated by stray electrical radiations.

A further object of the invention is to provide a fire and burglar alarm system having alternate sources of power.

Another object of the invention is to provide a fire and burglar alarm system having alternate sources of power which are provided with means to prevent a false alarm when the system is switched from one source of power to another.

A still further object of the invention is to provide a fire and burglar alarm system having an automatic self-checking means for indicating the operability of the system continuously.

Still another object of the invention is to provide a fire and burglar alarm system having all components of the system protected against attempts to open circuiting or short circuiting the master alarm by an intruder.

A still further object of the invention is to provide a burglar alarm system having a battery which is protected at all times from overcharging from the charge circuit and having means for indicating when the battery circuit is opened.

Other objects and many of the intended advantages of this invention will be readily appreciated by those skilled in the art as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 is a block diagram illustrating the functional relationship of an alarm system in accordance with the invention; and

FIGS. 2a and 2b, taken together, illustrate a circuit diagram in accordance with the invention.

Referring to FIG. 1 which illustrates the functional relationship of the fire and burglar alarm system embodying the present invention, there is provided a pair of terminals 11 for supplying the AC power to the system. The power is supplied by way of a stepdown and isolation transformer 15 which steps down the voltage from 117 volts, 60 cycles to volts, 60 cycles. The stepdown voltage is rectified and regulated by a rectifying and regulating unit 17 which is connected to the output of a stepdown and isolation transformer. A ground line bearing the numeral indicia 13 is for connecting all the components of the instant invention which are to have a conncction to ground. The output of the rectifier and regulator system 17 is connected to the input of the AC isolation diode unit 19. The output of the rectifier regulating unit is also connected to the circuit monitor relay 27 which activates upon the cessation of rectified AC current to switch the unit onto standby alarm power.

To this end there is provided a standby battery alarm power 29 having switches 26 and 28 in order to connect it into the system. A diode 25 is also connected from the output of the rectifying regulator 17 to one of the inputs of the trouble alarm 133. When the rectified current fails the trouble alarm 133 sounds the alarm. The output of the AC isolation diode is connected to the battery charging circuit for supplying the charging current to the battery 91. The battery 91 is connected continuously by way of a relay battery power supply circuit 37 to the alarm relay 21 for supplying the power to the relay in the event of a failure of the rectified current supply.

The AC isolation diode 19 output is also connected to the alarm relay 21 supplying the rectified current to the alarm relay unit for normal operation when operating from the l 17- volt mains. The output of the alarm relay is utilized for controlling the fire alann by switching the fire alarm switch 24 and the master alarm switch 34 to their closed positions, One of the outputs of the alarm relay 21 is connected to the heat detector 41. This output of the alarm relay 21 is utilized to supply the current which flows through the heat detector 41 when activated. The output of the heat detector is utilized 'to trigger the master alarm relay 43 for indicating a dangerous condition wherein there is a fire to be reported. The output of the master alarm relay 43 is connected to the input of a constant voltage generator 45. The output of the constant voltage generator 45 is utilized for operating a battery protection circuit 33. The master alarm 43 has an output 44 which is connected to the municipal system to initiate an alarm at the firehouse and thereby indicate that the protected premises are on fire.

An output of the battery 91 is also coupled to the battery protection circuit 33 for operating this circuit. The output signal from the rectifier and regulator provides the positive driving voltage to operate the circuit monitor relay 27. The negative side of relay coil 27 is applied to ground through the battery protection circuit 33 when operating properly.

The operation of the block diagram illustrated in FIG. 1 is as follows:

The incoming voltage supplied by the AC l l7-volt line from the powencornpany is stepped down and isolated by the unit 15 rectified by the rectifier and regulator 17 and directly fed to the circuit monitor relay 27. In the event of a power failure circuit monitor relay 27 switches on the standby battery 29 and also causes the trouble alarm 133 to operate. Additionally, the battery 9 l is provided for supplying operational currents to all the system components except the trouble and burglar alarm 133. In the event that the battery 91 malfunctions, then the battery protection circuit 33 operates the circuit monitor relay 27 which again would connectthe standby battery 29 to operate the trouble alarm 133. The fire alarm 131 is operated by the alarm relay 21 in response to the control of the heat detector 41. The heat detector 41 is also connected tothe master alarm relay for operating the master alarm at a remote indication. A zone annunciator 201 is provided to indicate the zone or location where the fire has started.

The system is provided with a burglar detector 137 for indication that the protected premises are being burglarized.

Referring now to FIGS. 2a and 2b, concurrently, wherein the circuit diagram is illustrated embodying the invention. The two FIGS. 2a and 2b are interconnected by lines A, B, C, D, E, F, G, H, I, respectively. Referring to FIG. 2a, specifically to the far upper left, this Figure has a pair of AC input leads. One of the AC leads 11 is connected to one end of the primary winding 58 of a stepdown transformer 57. The other end of the primary winding 58 of the stepdown transformer is connected through a fuse 51 and a switch 52 to the other AC input lead 11.

An indicator light 53 is connected in series with a limiting current resistor 55. The series combination of the indicator light 53 and the series resistor 55 are connected in parallel with the primary winding 58 of the transformer 57. The indicator light 53 indicates the presence of the AC power. As in FIG. 1, the number 13 indicates the electrical ground of the system. The secondary winding 60 of the stepdown transformer 57 has approximately a 28-volt output whenever the input AC voltage is 117 volts. This is merely given by way of explanation and other suitable voltages can be found for operating the equipment.

The rectifiers 59, 61, 63 and 65 cooperate to form a rectifying network for rectifying the AC present on the secondary winding 60 of the stepdown transformer 57. The cathode of diode 59 is connected to one end of the secondary winding 60. The anode of diode 59 is connected to the ground 13 and the anode of diode 61 is connected to ground 13; the cathode of diode 61 is connected to the other end of the secondary winding 60. A diode 65 has its anode connected to the cathode of a diode 59 and the cathode of diode 65 is connected to one end of a resistor 67. The diode 63 has its anode connected to the cathode of diode 61 and the cathode of diode 63 is connected to the cathode of diode 65. Resistor 67 acts as a currentlimiting resistor in this circuit and cooperates with Zener diode 74 to perform as the output voltage regulator.

A parallel filter combination of capacitor 69 and resistor 71 is connected between the system ground 13 and the other side of resistor 67. A diode 73 has its cathode connected to the cathode of a Zener diode 74 and its anode'connected to the resistor 67. The Zener diode 74 has its anode connected through a normally closed relay switch 26 to the ground 13. The Zener diode 74 limits the voltage at the cathode of diode 73 to the breakdown voltage of the Zener diode 74.

An indicator lamp 75a is connected in series with a resistor 77a for reducing the flow of current in the indicator lamp 75a. The series combination of the indicator lamp 75a and the se ries resistor 77a are connected in parallel with the Zener diode 74 and indicates the operability of the rectifying network. In the event that there is no rectified current passing through the diode 73 from the diodes 59, 61, 63 and 65 respectively, then the indicator lamp 75a is off. A second indicator lamp 75b is connected in parallel with indicator lamp 75a and is placed in another area on the premises to be protected to remotely indicate the operability of the apparatus by indicating the presence of rectified current. The indicator lamp 75b is connected over lines B and C. Similarly, the indicator lamp 75b is connected in series with a current limiting resistor 77b.

A rechargeable battery 91 having a plurality of cells has its positive end connected to one end of a switch 89. The switch 89 is provided for connecting and disconnecting the battery 91 from the circuit. The normally closed switch 89 is operated simultaneously with the switch 87 which connects the battery by way of a line D to the switch terminal of switch 104 of the relay 101. The switch 89 connects the battery 9 with the cathode of the diode 83. The anodevof diode 83 is connected to one end of a current limiting resistor 81. The other end of the current limiting resistor 81 is connected to the cathode of diode 73. The negative terminal of the battery 91 is connected through a fuse 93 which protects the battery circuit from becoming overloaded. The other end of the fuse 93 is connected to the cathode of diode 95 and toe cathode of diode 95 is connected to the junction of variable resistor 155 and the emitter electrode 152 of the transistor 151. The anode of diode 95 is connected to the electrical ground 13. The diode 95 provides a shunt path around'the variable resistor 155 when testing the charge conditions of the battery. 91, thereby providing protection of the emitter to base junction of transistor 151, and also diode 95 provides low impedance path for activation of fire alarm relay coil 1 19.

The variable resistor 155 has its free end connected to the electrical ground 13 of the system. The variable resistor 155 controls the charging rate of the battery 91. A pushbutton switch 97 is connected in series with an indicator lamp 99. The combination of the pushbutton 97 and series connected indicator lamp 99 is connected between the positive end of battery 91 and the electrical ground 13. When the pushbutton 97 is depressed the condition of the battery is indicated by the brightness of the indicator lamp 99.

A relay winding 101 has one end of its control winding connected through line E to the cathode of diode 85. The other end of the control winding 101 of the relay is connected to the parallel combination of the temperature sensing circuit. The temperature sensing circuit comprises thermal switch 108a, and resistor 107 is connected in parallel to the cathode of diode 302, thermal switch 110a, and resistor 109 connected in parallel to the cathode of diode 301, and thermal switch 112a connected in parallel to the cathode of diode 300. Any suitable relay with suitable threshold activation voltage may be used for the relay 101. A suitable relay is the Sigma Model 42RO-2500S-S1L described in Sigma Relay Catalog, issued Jan. 1967, publish ed by Sigma Instruments Inc., Braintree, Mass.

The temperature sensor switch 108a is provided with a parallel pushbutton switch 108 for testing the circuit, the temperature sensor switch 1100 is provided with a pushbutton switch 110 for testing its circuit, and the temperature sensor switch 112a is provided with a pushbutton 112 for testing its circuit. Resistors 107, 109 and 111 complete the circuit in the absence of a fire. It is to be noted that merely three temperature sensors and annunciators are shown for the purposes of explaining the invention. However, as many temperature sensors and annunciators as needed may be utilized in this system. Lamp 401 is connected between the thermal switch 112a and the anode of diode 73 and lights when thermal switch 112a activates. Similarly, lamp 403 is connected between the thermal switch 110a and the anode of diode 73 and lamp 402 is connected between the thermal switch 108a and the anode of diode 73. When the respective thermal switches are open then lamps 401, 402, 403 do not get sufficient current to light.

The relay winding 101 is provided with a diode 103 which has its cathode connected to the end of the winding 101. The anode of diode 103 is connected to the other end of the relay winding 101. The diode 103 discharges the transients in the reverse direction which are present when the current drops below threshold level in the relay winding 101. An integrating capacitor 105 is connected in parallel with diode 103 and the integrating capacitor functions to isolate the system from stray fields caused by bolts of lightning during a thunderstorm, transients caused by power failure, switching the system from AC rectified power to battery power, and other electrical disturbances. A pushbutton switch 106 is provided for simulating the operation of a heat sensor which causes the alarm to operate/The terminal 102 of the relay 101 is connected by way of a lead A to the switch 28. The switch 28 is normally connected to the output of the rectifier at the junction of resistors 67 and 71. In the event of a power failure switch 28 is activated by the relay 161 switching the switch 28 to the battery 29. (Operation of relay coil 161 will be described hereinafter).

The return leads from the temperature sensors 108a, 110a and 112a are connected to the anode of a diode 115. The cathode of the diode 115 is connected to one end of a switch 104 and to the switch a. The switch 1250 is connected through a cable 124 to a remote fire station. A relay 119 is provided in the remote fire control station for operating the switches 121 and 123. When the switch 123 closes, it operates a nonillustrated fire alarm at the remote fire station which indicates the location of the fire. The relay 119 is provided with a 50-millisecond delay before actuation. Any suitable relay which will operate with a SO-millisecond delay before actuation may be used for relay 119. A suitable relay is the Eagle Auxtrip No. A21757-3 described in Bliss Gamewell Bulletin 3130 published by Bliss Gamewell Co., Newton, Mass. The switch 125a is provided as a safe arm switch and is connected to the resistor 127. When it is desired to carry out maintenance on the system the switch 125a is closed so that a false alarm would not be given (relay coil 119 is open circuited), and resistor 127 is inserted as a substitute load for coil 1 19.

A current limiting resistor 117 is connected in circuit between the switch 104 and the switch 123 for limiting the current flow in the circuit path only after the relay coil 1 19 has been activated. When maintenance is performed on the system, the switch 125 is closed and then the rectified power from the rectifier section of the circuit is connected by way of a lead 126 to the switches 134 and 1340 and thence to the trouble alarm indicators 133 and 13311. It is to be noted that the trouble alarm indicators 133 and 13311 and the alarms are located at various positions on the premises and merely two are disclosed for symbolic explanation of the system, but as many units as needed may be provided within the scope of this invention.

A diode 129 is provided to operate all alarms simultaneously in the event of fire and has its cathode connected to the switch 125 and its anode is connected to the alarms 131 and 131a. When the relay 119 activates, the switch 121 operates and removes itself from the circuit and switch 123 operates connecting resistor 117 to the junction of 127 and switch connects the alarms 131 and 131a to the power supply of this system. In the event it is desired to have a burglar alarm, the windows or doors etc., of the area to be protected are each provided with switches 137a, 137b, 1370 and 137n. A pushbutton 140 is provided in series with the resistor 127 and when it is depressed it causes the trouble alarm to be sounded as will be indicated hereinafter. 1n the event any of the switches 137a, 137b, 1370 and 137n are open or their respective circuits are broken, then the trouble indicator alarm will be sounded. A switch, preferably operated by a key is provided near the door for turning the burglar alarm on and off. An indicator light 113 is provided which lights up whenever the burglar alarm switch 139 is turned to its on condition.

The other end of the wire leading from the burglar alarm switches is connected to one end of an integrating capacitor 141. A first diode 143 and a second diode 145 are connected in series across capacitor 141. The free end of capacitor 141 is connected to the electrical ground 13 of the system. The cathode of diode 145 is also connected to the electrical ground and the cathode of diode 143 is connected to the anode of diode 145. A resistor 147 is connected between the junction of the anode of diode 143 and a capacitor 141 and the base of the transistor 151. The combination of resistor 147 and capacitor 141 is a low-pass filter and prevents the circuit from operating unless there has been a fault (fire or burglar alarm, etc., condition) present for several hundred milliseconds. This is provided to prevent the operation of the system in response to superfluous transients and other electrical disturbances.

The collector 154 of the transistor 151 is connected to the parallel combination of the capacitor 157, the diode 159 and the relay coil 161. The relay 161 is normally opened in the absence of current. When the relay coil 161 draws current then the relay contacts are as shown in FIG. 2a of the drawing. A suitable relay is the Sigma Model 42RO-2500S-SIL, described in Sigma Relay Catalog, published by Sigma Instruments lnc., Braintree, Mass.

The anode of diode 159 is connected to the collector of the NPN transistor 151. The cathode of the diode 159 is connected to the junction of resistor 67 and the anode of diode 73. A charging diode 226 has its anode connected to the anode of diode 73 and its cathode connected by a switch 157 and a fuse 177 to the positive terminal of a battery 29. The negative terminal of the battery is connected by way of a trickle charge resistor 225 to the electrical ground 13 of the system. The fuse 177 is to protect the battery 29 from surge and overload currents. The switch 175 is provided so that the battery 29 can be disconnected from the circuit and replaced. Switch 179 is provided to disable trouble alann switches 134 and 134a. A terminal board for interconnecting the circuit elements is schematically illustrated as unit 200.

The operation of the system is as follows:

The switch 52 is closed and the circuit is connected to a source of AC power. The voltage is stepped down by way of a transformer 57 and rectified in the rectifying section of the circuit. Indicator 53 indicates the proper operation of the AC power and indicator lights 75a and 75b indicate the proper operation of the rectifier circuit. In the event that the AC power is lost and therefore the rectifying power is also lost, the relay 161 is deactivated and returns to its normally open position, thereby connecting the battery 29 to switch 28. The indicator lights 75a and 75b go off indicating the loss of the rectified power supply. Additionally, the trouble alarms 133 and 133a go on indicating a fault condition. It is to be noted that the transistor 151 is normally conductive thereby assuring that the relay coil 161 is on holding contacts to the positions shown in the drawing. However, if anything occurs to cause the transistor 151 to cease conduction, then the relay 161 is again automatically deactivated causing the battery 29 to be placed in the circuit and also causing the trouble alarms 133 and 133a to sound the trouble alarm. If, for any reason, battery 91 should short circuit or should resistor 81 or diode 83 become defective, the voltage generated across variable resistor 155 will increase causing the transistor 151 to turn off thus disabling the relay 161 which, in turn, will activate trouble alarms 133 and 1330.

Activation of any of the heat detecting elements 108a, 110a or 112a or by their associate short circuit causes the current level of the relay coil 101 to increase beyond threshold which causes the relay 101 to operate closing switches 102 and 104 which in turn supplies power to the relay coil 119 from the battery 91 and simultaneously applies operating power to the fire alarms 131 and 131a and trouble alarms 133 and 133a. The relay 119 has a SO-millisecond delay in its operation and when it operates it opens up the contacts 121 and .closes the contacts 123. Increased current flowing in the fire detectors circuit causes the relay 101 to operate, which applies power to coil 119 which in turn operates contacts 121 and 123 after a SO-millisecond delay. Operation of this relay coil 119 opens its own power supply line by opening the switch 121 and the relay 119 simultaneously closes the switch 123, thereby placing a resistor 117 as a load in series with the alami circuit which assures that the alarm circuit continues to operate. When the relay coil 119 activates at the fire station, it also sets off the fire alarm therein which indicates the presence of a fire on the premises being protected. The relay 161 will be deenergized and cause the trouble alarms 133 and 133a to operate in the event of a short circuit to ground of any element in the alarm relay groups 101 and 119 and in the event that any of the lines in this group should be broken, the relay 161 will operate.

It is to be noted that activation of the pushbutton 106 will cause the fire alarm to be sounded and activation of the pushbutton will cause the trouble alarms 133 and 133a to be sounded. The diode 226 provides power for the trouble alarms as long as there is AC rectified power in the circuit.

Obviously, many modifications and variations of the present invention are possible in the light of the above teaching. it is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A fire alarm system for indicating a fire in a given area comprising a fire sensor, means for identification of fire area or zone, means for giving a first audio alarm responsive to said fire sensor, said fire sensing responsive alarm means being connected in circuit with said fire sensor, a first power supply for operating said fire alarm system connected to said fire sensor and a second power supply, means responsive to a failure of said first power supply for connecting said second power supply to said fire sensor, and means for preventing the false activation of said first means for giving an audio alarm due to electrical transients generated during the operation of said fire sensor means connected to said means for giving a first audio alarm, thereby preventing the activation of said audio alarm by electrical radiations generated by bolts of lightning and other stray electrical noise, a trouble alarm and means responsive to the failure of said first power supply and to malfunction of said second power supply for actuating said trouble alarm connected to said trouble alarm, means for sensing a burglary connected in series circuit with said fire sensor but capable of activating only the trouble alarm but incapable of inadvertant operation of the fire alarm circuit, and said burglary sensing means causing said series circuit to be broken when a burglary is detected, thereby causing said trouble alarm to activate and said fire alarm remaining in a nonactivated condition.

2. A fire alarm system as defined in claim 1, but further characterized by having visual means for indicating the operability of said first power supply connected in parallel with said first current source.

3. A fire alarm system as defined in claim 1, but further characterized by having a third power supply, said means responsive to a failure of said first power supply for connecting said second power supply to said fire sensor connecting said third power supply to said trouble alarm means.

4. A fire alarm system as defined in claim 3, wherein said first power supply comprises: a transformer having a secondary winding, means for rectifying an AC current connected to said secondary winding and means for regulating the output voltage of said current rectifying means connected to said current rectifying means.

rent rectifying means.

6. A fire alarm as defined in claim I, but further characterized by having annunciator means for indicating the location of the fire on the premises to be protected.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2041540 *Jun 30, 1931May 19, 1936Benjamin GoldstoneAlarm apparatus
US2492432 *Jul 27, 1946Dec 27, 1949Electro Protective CorpElectrical protective alarm system
US2599623 *Aug 30, 1950Jun 10, 1952Forrester Herman GClosed circuit fire and burglar alarm
US2605342 *Dec 10, 1948Jul 29, 1952Robert C CollinsFire alarm system
US2701874 *Jan 23, 1950Feb 8, 1955Harold A MearsBurglar alarm system
US2767393 *Aug 3, 1953Oct 16, 1956Kidde & Co WalterApproach alarm system with unwanted signal elimination
US2895125 *Dec 9, 1954Jul 14, 1959Patrick F HenryElectrical alarm system
US2971184 *May 14, 1957Feb 7, 1961American District Telegraph CoIntruder alarm system
US3013257 *Mar 11, 1959Dec 12, 1961Dual Lite Company IncBattery failure alarm
US3049623 *Mar 30, 1961Aug 14, 1962W W Henry CompanyAuxiliary power supply
US3060416 *Mar 18, 1960Oct 23, 1962Honeywell Regulator CoSupervised signal system
US3174143 *Dec 11, 1961Mar 16, 1965Akin Phillip AElectrical protective system
US3189788 *Jan 3, 1961Jun 15, 1965Cady Charles APower failure responsive circuits
US3230518 *Mar 20, 1961Jan 18, 1966American District Telegraph CoMethod of detecting intruders and intruder detection apparatus of the capacity-type utilizing balanced asymmetric fields
US3418487 *May 25, 1966Dec 24, 1968U C Lite Mfg CompanyEmergency power supply system
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3710134 *May 10, 1971Jan 9, 1973Alarm Device MfgPower supply for alarm system
US3721887 *Nov 24, 1971Mar 20, 1973American Telephone & TelegraphBattery protection circuit
US3753001 *Jun 29, 1972Aug 14, 1973Nissan MotorElectric power supply system using back-up capacitor
US3784892 *May 20, 1971Jan 8, 1974Gen Syst IncBattery charging system for emergency battery systems
US3798638 *Feb 9, 1972Mar 19, 1974Goldschmied SAudio responsive light display
US3801978 *Jul 20, 1972Apr 2, 1974E Systems IncUltrasonic-microwave doppler intrusion alarm system
US3886534 *Jan 8, 1973May 27, 1975Polar CorpSecurity system
US4027302 *Jun 3, 1976May 31, 1977W. E. Healey & Associates, Inc.Double detection circuit for conserving energy in fire detection systems and the like
US4057798 *Mar 3, 1976Nov 8, 1977George Andrew EllsonSecurity system
US4150369 *May 20, 1977Apr 17, 1979Gaspari Russell AIntrusion alarm system
US4191946 *Oct 20, 1977Mar 4, 1980Gonzalez Raymond JWarning apparatus with a line integrity supervisory circuit
US4199754 *Nov 21, 1977Apr 22, 1980Esb IncorporatedCircuit for an emergency lighting and fire detector system
US4207511 *Sep 15, 1978Jun 10, 1980Ford Motor CompanyCircuit for constant voltage power source
US4219807 *Apr 17, 1978Aug 26, 1980Cathodic Protection Services, Inc.Sensor system for an impressed cathodic protection circuit
US4271405 *Jan 3, 1978Jun 2, 1981Kitterman Lawrence PAlarm control system
US4272650 *Oct 16, 1978Jun 9, 1981International Mobile Machines IncorporatedPower supply system
US4399396 *Aug 3, 1981Aug 16, 1983Hase A MTwo level constant voltage float charge rectifier and battery surveillance apparatus
US4588989 *Feb 15, 1984May 13, 1986Mitutoyo Mfg. Co., Ltd.Supervisory device for wrong operation of varying quantity measuring apparatus
US4618857 *Jun 20, 1984Oct 21, 1986Harvey W. DuboisLow D.C. and loss of A.C. sensor and alarm with service inhibitor
US4672228 *Sep 3, 1985Jun 9, 1987Pioneer Magnetics, Inc.Battery backup system for switched power supply
US4672293 *Aug 26, 1985Jun 9, 1987Crampton Timothy PPower-supply/battery back-up power supply/battery charger combination
US4885521 *Dec 15, 1987Dec 5, 1989Applied Research & Technology, Inc.Unique computer power system with backup power
US5237258 *Sep 7, 1989Aug 17, 1993Applied Research And Technology, Inc.Unique computer power system with backup power
US5804891 *Mar 31, 1997Sep 8, 1998Sentrol, Inc.Battery saving switching mechanism
US5812391 *Nov 21, 1994Sep 22, 1998Solid State Securities, Inc.Door control system and release mechanism
CN102456260A *Oct 29, 2010May 16, 2012陈同Laboratory security alarm system
Classifications
U.S. Classification340/506, 340/541, 340/693.2, 340/333, 307/66, 340/584, 340/521
International ClassificationG08B19/00
Cooperative ClassificationG08B19/00
European ClassificationG08B19/00