US3510863A - Apartment alarm - Google Patents

Apartment alarm Download PDF

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US3510863A
US3510863A US3510863DA US3510863A US 3510863 A US3510863 A US 3510863A US 3510863D A US3510863D A US 3510863DA US 3510863 A US3510863 A US 3510863A
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relay
switch
contacts
contact
alarm
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John E Mcbrian
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Kidde Inc
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Kidde Inc
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    • GPHYSICS
    • G08SIGNALLING
    • G08BSIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00Burglar, theft or intruder alarms
    • G08B13/02Mechanical actuation
    • G08B13/08Mechanical actuation by opening, e.g. of door, of window, of drawer, of shutter, of curtain, of blind

Description

J.'| MQBRIAN APARTMENT ALARM Filed March 29. 1967 May 5, 1970 INvEN'roR JOHN E McBRIAN AGENT United States Patent US. Cl. 340-276 7 Claims ABSTRACT OF THE DISCLOSURE An alarm apparatus for protecting the door of an apartment or the like including a single-pole double-throw relay for operating an alarm device instantly upon opening of the door in one mode of operation and including other single-pole relays which in a second mode of operation with the first relay to form a logic circuit which is actuated by opening and closing the door in exiting from the apartment and places the apparatus in condition to respond to a subsequent opening of the door to initiate an alarm and which also includes an electrical time delay unit associated with the alarm device to permit the apparatus to be turned off by a key operated switch before the alarm is sounded.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to burglar alarm apparatus automatically responsive to the opening of a door and, more particularly, to such apparatus for protecting an apartment which allows the occupant to turn on the device and then leave the apartment, the device thereafter being conditioned to actuate an alarm, after a time delay, when the door is subsequently opened and also allows the occupant to turn the apparatus off before the alarm is given.

Description of the prior art Burglar alarm devices of the above described type which have been employed in the past have not been entirely satisfactory for several reasons. Some of these prior devices have been mechanical in nature and were secured directly to the door, to be operated by the motion of the door, or the knob thereof, and contained a spring motor driven escapement type timing mechanism. These devices have the disadvantage of being readily apparent both visually and by the ticking sound they make so that a burglar could easily locate and impair the mechanism to render it incapable of giving an alarm. Other prior art devices, while electrical in nature and designed to be both silent and remotely located from the door have been unsatisfactory 1) because of high cost, due to the use of a large number of components and the use of components of an expensive nature such as multiple pole re ays; and (2) because they had limited flexibility in providing features in addition to a door actuated alarm.

SUMMARY OF THE INVENTION It is an object of the present invention to provide improved apartment alarm apparatus of the type described under Field of the Invention which is silent, unobtrusive, and inexpensive.

Another ,object is to provide such apparatus which is capable of a plurality of modes of operation.

Another object is to provide such apparatus which is capable of providing features in addition to a door actuated alarm.

Other and further objects of the invention will be obvious upon an understaning of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein 3,510,863 Patented May 5, 1970 will occur to one skilled in the art upon employment of the invention in practice.

In accordance with the present invention, the foregoing objects are generally accomplished by providing in intruder detecting alarm apparatus a closure operated switch having a first condition when the closure is closed and having a second condition when the closure is opened, first switch means responsive to the condition of the closure operated switch having a first position when the closure operated switch is in the first condition and a second position when the closure operated switch is in the second condition, second switch means responsive to the operation of the first switch means to be operated when the first switch means is in the second position as a result of the opening of the closure, third switch means responsive to the first and second switch means to be operated when the first switch means is moved into the first position in response to the closing of the closure after the second switch means has been operated, and alarm means responsive to the first and third switch means to be operated when the first switch means is moved into its second position as a result of a re-opening of the closure after the third switch means has been operated.

BRIEF DESCRIPTION OF THE DRAWING of the specification, wherein the single figure of the drawing is a schematic wiring diagram of an apartment alarm in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing in detail, there is shown an apartment alarm apparatus according to the present invention which generally comprises an electrical power supply 10, a single pole single throw door operated switch 11, an alarm horn 12, an on-off switch 13, a double pole double throw manual switch 14 for selecting either an Exit or Night mode of operation, an electrical timer 15 for delaying the operation of the horn in the Exit mode, a single pole double throw relay 16 under the control of the contact switch 11, and second and third single pole relays 17 and 18 which co-act with the relay 16 to form a logic circuit operative in the Exit mode. These elements with the exception of the door switch 11 are preferably mounted within a housing 19.

The apparatus is designed to accommodate optional auxiliary devices including a lamp control unit 20 into which a table lamp or the like may be plugged to provide light upon re-entering the apart-ment, a standby battery unit 21 for providing emergency power, a remote signaling unit 22, and auxiliary alarm contact devices 24 such as fire detecting units or panic switches.

The power supply 10 includes a conventional line plug 25, a stepdown transformer 26 having a primary winding 27 connected to the plug 25 and a secondary winding 29 having end terminals 30 and 31 and a center tap terminal 32, three diodes 34, 35 and 36 connected respec tively to the terminals 30, 31 and 32, and a lamp 37 connected across the primary winding 27 to indicate the condition oft he AC input to the transformer. The diodes 34 and 35 are poled to conduct positive current flow and are connected to a main positive conductor 39, and the diode 36 is poled in the opposite direction and is connected to a main negative conductor 40.

The door contact switch 11 is adapted to be mounted on the door or the door frame of the apartment at a distance from the control circuitry which is preferably housed in a box located in an inconspicuous place such as in a closet. The switch 11 may be any of the conventional door switches known to those skilled in the art. It is the door is closed and open when the door is opened, and it is connected to the circuitry in the housing 19 by a pair of conductors 41 and 42.

The alarm born 12 includes a winding 44 connected in series with a movable contact 45 in the form of a sound producing diaphragm and a stationary contact 46. The on-olf switch 13 is of the key operated type so that only the occupant of the apartment can turn the apparatus ofi once it has been activated. A diode 47 is connected in parallel with the winding 44 to suppress inductive transients in voltage.

The mode switch 14 includes a pair of movable contacts 49 and 50 ganged together, each of which has associated therewith a stationary Exit contact 51 and 52 respectively and a stationary Night contact 54 and 55 respectively. A pair of lamps 48 and 53 are associated with the switch 14 to make the position of the switch readily apparent.

The timer includes a heater resistor 56, a bi-metallic arm contact 57 adapted to bend when heated, and a stationary contact 59 positioned to contact the arm 57 when the arm bends in response to heating.

The relay 16 includes a coil 60, a movable contact 61 and a pair of stationary contacts 62 and 64. The coil 60 is connected in series with the door switch 11 and the heater resistor 56 between the main conductors 39 and 40. The movable contact 61 is connected to the main conductor 39 through the on-off switch' 13. The stationary contact 62 is connected to the movable contact '50 of the mode switch 14.

The relay 17 includes a coil 65, a movable contact 66, and a stationary contact '67. The lower end of the coil 65 is connected to the main negative conductor 40. The upper end of the coil 65 is connected to the contact 52 of the switch 14 through a diode 69, and is also connected through a capacitor 70 to the main positive conductor 39. The movable contact 66 is connected to the stationary contact 64 of the relay 16. The contact 67 is connected to the upper end of the coil 65 through a diode 71.

The relay 18 includes a coil 72, a movable contact '74, and stationary contacts 75 and 76. The lower end of coil 72 is connected to the main negative conductor 41. The upper end of the coil 72 is connected to the contact '67 of the relay 16 through diode 77, and is also connected to the Night contact 54 of the switch 14 through a diode 79. The movable contact 74 is connected to the contact 62 of the relay 16 through a diode 80 and the stationary contact 75 is connected to the main positive conductor 39. The stationary contact 76 is connected through the heater resistor 56 of the timer 15 to the negative conductor 40, and is also connected through a diode 81 to the upper end of coil 72. The stationary contact 59 of the timer 15 is connected to the contact 76 through a diode 82 and is also connected to the Exit contact 55 of the switch 14. The alarm horn 12 is connected between the contact 59 of the timer and the negative conductor 40. The bimetallic contact 57 of the timer 15 is connected to I the movable contact 61 of the relay 16. A resistor 84 and a diode 85 connected in parallel provide the connection between the coil 60 of the relay 16 and the heater 56 of the timer 15. A capacitor 86 is connected between the negative conductor 40 and the lower end of the coil 60 of the relay 16, and a capacitor 87 is connected between the conductors 39 and 40.

The lamp control unit includes a relay 90 having a coil 91 and a pair of contacts 92, a line plug 94, and a plug receptacle 95. The coil 91 is connected in series with a diode 96 between the terminal 32 of the power supply 10 and the movable contact 74 of the relay 18. The contacts 92 are connected in series with the plug 94 and the receptacle 95. A lamp 93 is shown connected in parallel with the coil 91 to provide a remote indication which can be used, as described hereinafter, as an at home to visitors signal.

arranged so that the contacts thereof are closed when used, as described hereinafter, as an at home to visitors signal. 1

The battery standby unit 21 includes a battery 97, and a relay 99 having a coil 100 and a pair of contacts 101. The coil 100 is connected between the main positive conductor 39 and terminal 32 of the power supply 10. The contacts 101 and the battery 97 are connected in series between the positive conductor 39 and the negative conductor 40.

The remote signal unit 22 is connected in parallel with the horn 12 and' may be an annunciator located in the superintendents quarters of the apartment building.

The alarm contacts 24 are connected in parallel with each other in series with alarm horn 12 between the positive conductor 39 and the'negative conductor 40.

In operation, when the plug 25 is inserted into a wall receptacle within the apartment, the relay 16 is activated each time the switch 11 is closed in response to the apartment door being closed. Until the switch 13 is turned on, the horn 12 can be activated only by the auxiliary contacts 24 as described hereinafter in detail. When the occupant of the apartment is about to leave the apartment and wishes the apartment to be protected during his absence, he places the mode switch 14 in the EXIT position and closes the switch 13 with the key provided for that purpose. At this point, the apartment door is closed and current is flowing from the positive conductor 39 through the switch 11, the relay coil 60, the diode and the heater resistor 56 to the negative conductor 40. This current flow is limited by the resistance of the coil 60 so that no heating of the resistor 56 results. The relay 16 is thereby energized and the movable contact 61 is held against the contact 64. In response to the closing of the switch 13, the EXIT lamp 48 is illuminated.

When the occupant opens the door to leave the apartment, the switch 11 opens and the relay 16 drops out placing the contact 61 against the contact 62. Current now flows through the switch 13, the contacts 61 and 62, the contacts 50 and 52 of the switch 14, the diode 69 and the coil 65 of the relay 17 to the conductor 40. The relay 17 pulls in closing the contacts 66 and 67.

As the occupant closes the door behind him, the relay 16 is re-energized pulling the contact 61 against contact 64 again. Current then flows through the contacts 61 and 64 and the contacts 66 and 67. The current flow then divides, part flowing through the diode 71 to latch the relay 17 and part flowing through the diode 77 to energize the relay 18. The contact 74 is drawn against the contact 76 to connect the contact '62 of relay 16 to the heater resistor 56. The apparatus is now armed to protect the apartment against unauthorized entry.

When the door is opened, either by a burglar or the occupant upon his return, the relay 16 drops out placing the contact 61 against the contact 62. Full current then flows from the switch 13 through the contacts 61 and 62, through the diode 80, and through the contacts 74 and 76 to the heater 56.

The contact 76 is now at the potential of the positive conductor 39. This latches the relay 16 in the de-energized condition since the coil 60 has the same positive potential applied to both of its ends. Therefore, reclosing the door has no effect upon the unit. Current also flows from the contact 76 through the diode 81 to latch in the relay 18.

The heater resistor 56 requires a predetermined time (for example 15 seconds) for it to heat the bimetal contact 57 to the temperature at which it bends into contact with the contact 59. At the end of this time interval, the contacts 57 and 59 close and full voltage is supplied to the horn 12. If the door was opened by the returning occupant, he prevents the alarm from sounding by opening the key operated switch 13 before the time interval has expired. A burglar entering the apartment Will not be able to turn off the unit, even if he is aware of its existence, and the alarm will sound.

The capacitor 86 is provided to prevent an alarm from sounding as a result of normal vibrations of the door which might momentarily open the switch 11. Such vi brations or rattling of the door could result from wind or from an innocent person knocking on or trying the door. When the door is closed and the relay 16 is energized, the capacitor 86 is subjected to a very small charging potential because one side of it is connected to the negative conductor 40 while the other side differs from the potential of the conductor 40 only by the small voltage drops across the diode '85 and the low resistance heater 56. When the door switch 11 is opened after the occupant has exited, the capacitor 86 begins to be charged by current flowing through the resistor 84 from the contact 76. If the door switch 11 is opened only momentarily, the capacitor will not have achieved a full charge and upon reclosing of the switch 11 current will flow through the coil 60 of the relay 1-6 to the capacitor 86 until the capacitor is fully charged. This charging current through the coil 60 pulls in the relay 16 to place the apparatus once again in the armed condition.

The lamp control unit 20 is provided primarily as a convenience to the occupant of the protected apartment to automatically provide light so that the apparatus may be turned on and off more conveniently. This light is provided by any conventional lamp -(not shown), such as a table lamp in the entry hallway which is plugged into the receptacle 95, the plug 94 being inserted in any standard receptacle. When the apparatus is turned off (switch 13 is in its open posiiton) current flows from the positive conductor 39 through the contacts 75 and 74 of the deenergized relay 18, and through the diode 96 and the relay coil 91 to the terminal 32. The relay 90 is thus energized to hold contacts 92 closed so that the receptacle 95 is connected in series with the plug 94. The hall lamp can at all times be used normally by switching it on and oil as desired.

When the occupant prepares to leave the apartment and expects to return at night, he turns on this hall lamp and sets the apparatus as above described. As the door closes behind him, the relay 18 is energized as described above and the motion of the contact 74 interrupts the current flow to the relay coil 91. The contacts 92 open and the lamp goes out. When the door is opened again, current to the relay coil 91 is supplied through the diode 80 and the relay 90 is reenergized and the hall lamp goes on to enable the occupant to quickly turn olf the apparatus.

The battery standby unit 21 is designed to supply power to the apparatus should the normal AC power to the apartment fail. Under normal conditions, current flows through the coil 100 from the positive conductor 39 to the terminal 32 and the contacts 101 are held apart.: When the AC power fails, the relay 99 drops out closing the contacts 101 to connect the battery 97 between the positive conductor 39 and the negative conduction 40. The relay coil 100 is isolated from the battery 97 by the diode 36 to maintain it in the de-energized condition until the AC power is restored. During the normal operation, the capacitor 87 charges to the full supply voltage. When the AC power fails, this capacitor discharges to insure that power is supplied to the, apparatus during the changeover to the standby battery.

If the apparatus is used without a standby battery unit, an AC power failure would allow all of the energized relays to drop out. If the apparatus were armed in the exit mode at the time of the power failure, and the relays 17 and 18 were not re-energized upon the restoration of power, then a burglar could enter without causing an alarm. The capacitor 70 is provided to cause the relays 17 and 18 to be re-energized automatically when the AC power is restored so that the apparatus is placed back in the armed condition. When the apparatus is turned on and is in the exit mode and AC power fails and is restored, current flows through the coil 65 of the relay 17 until the capacitor 70 is charged. This current flow pulls in the relay 17 closing its contacts 66 and 67. The relay 16 pulls in immediately upon restoration of power, current flows through the contacts of the relay 16 and the relay 17 to cause relay 18 to pull in so that the apparatus is brought back to the armed condition.

When the occupant of the apartment is about to go to bed (or at any time he desires an alarm to be given should anyone enter the apartment while he is in the apartment), he sets the mode switch 14 in the Night position and closes the switch 13. Current then flows from the switch 13 through the contacts 49 and 54 and through the diode 79 to energize the relay 18 and pull the contact 74 against the contact 76. The operation of the relay 18 cuts off the current supplying the lamp control unit and the hall lamp (if one is being used) is extinguished. The placing of the mode switch in the Night position also lights the Night light 53 and connects the relay contact 62 directly to the alarm horn 12 through the contacts 55 and 50 of the switch 14.

When the door is opened while the apparatus is in this condition, the relay 16 drops out placing the contact 61 against the contact 62. Current then flows from the switch through the contacts, and through the switch 14 to the alarm horn 12. The timer 15 is thus bypassed and the horn sounds immediately. At the same time, current also flows from the contact 62 through the diodes 80 and 96 to the lamp control unit 20 to turn on the hall lamp. Since the relay 18 is latched in through the diode 79, the current flow through the diode 80 places the contact 76 at the potential of the conductor 39 to prevent the relay 16 from pulling in if the door is reclosed by the intruder. The capacitor 86 operates in the same way described hereinbefore to prevent rattling of the door from latching the relay 16 in the de-energized condition. Since there is no time delay in this mode of operation, rattling of the door may produce an instantaneous sounding of the horn 12 which would indicate that the door switch is not properly positioned or adjusted. If desired, the lamp 93 is located on a nameplate panel at the entrance of the apartment house. This lamp would be illuminated whenever the occupant of the apartment was at home except when he had activated his apparatus in the Night position. Thus, if the lamp is not illuminated it would indicate that the occupant was either out or did not want to be disturbed.

The normally open auxiliary alarm contacts 24 are connected directly between the positive conductor 39 and the alarm horn 12. One or more of these contacts may be temperature sensitive to detect fires and one or more may be manual locking push buttons to summon help in the case of emergency. The temperature sensitive type contact could include a bimetal strip which bends in response to heat so as to close a pair of contacts or it may contain spring loaded contacts which are normally held apart by a device which melts at a low temperature to allow the contacts to close. Whenever one of the contacts 24 closes, the alarm horn is sounded regardless of the setting of the mode or the on-otf switch of the apparatus. This alarm will continue to sound until the contact 24 is reopened or until both AC and standby power is disconnected.

From the foregoing, it will be seen that the present invention provides an improved apartment alarm apparatus which is silent, unobtrusive, inexpensive; is capable of a plurality of modes of operation; and is capable of providing features in addition to a door actuated alarm.

As various changes may be made in the form, construction and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein, is to be interpreted as illustrative and not in any limiting sense.

I claim:

1. In intruder detecting alarm apparatus, a source of electrical power, a closure operated switch connected to said source and having a first condition when the closure is closed and having a second condition when said closure is opened, a first relay including a coil responsive to the condition of said closure operated switch and including contacts having a first position when said closure operated switch is in said first condition and having a second position when said closure operated switch is in its said second condition, a second relay including a coil responsive to the Operation of said first relay and including contacts to be operated when said first relay contacts are in said second position as a result of opening of said closure, a third relay including a coil responsive to said first and second relay contacts and including contacts to be operated when said first relay contacts are moved into said first position in the response to the closing of said closure after said second relay contacts have been operated, alarm means responsive to said first and third relay contacts to be operated when said first relay contacts are moved into the second position as a result of a reopening of said closure after said third relay contacts have been operated.

2. Alarm apparatus according to claim 1, including a manual switch for connecting said first relay contacts to said alarm means so as to operate said alarm means when said first relay contacts are placed in said second position in response to any opening of said closure.

3. Apparatus according to claim 1, including an onoil switch connected between said first relay contacts and said source of electrical energy and a lamp control relay having a coil connected to be energized through said third relay contacts when said on-off switch is in the oil position and connected to be energized through said first relay contacts when said first relay contacts are in said second position and said on-ofi switch is in the on position, said lamp control relay having contacts for connection between a lamp and a source of electrical power.

4. Apparatus according to claim 1, wherein said first relay contacts include a first stationary contact connected through said second relay contacts to supply power to the said third relay coil, a second stationary contact connected to supply power to said second relay coil, and a movable contact connected to said power source and being in contact with said first stationary contact in said first position and in contact with said second stationary contact in said second position, and wherein said first relay coil is connected in series with said closure operated switch across said source of power, and including an on-ofif switch connected between said power source and said movable contact, and also including a capacitor connected in series with said second relay coil across said source of power to provide a charging current path through said second relay coil to operate said second and third relays at the end of a power interruption when said on-otf switch is closed.

5. Apparatus according to claim 1, including a timer for delaying the operation of said alarm means for a predetermined time interval after said first relay contacts are moved into the second position subsequent to said third relay contacts being operated, said timer including a switch connected to operate said alarm means and a slow acting switch operator under the control of said third relay contacts, said first delay coil being operated in series with said switch operator and said first and third switch contacts are connected in a series circuit with said switch operator in a manner so that said first relay coil is prevented from being energized when said first relay contacts, said first relay coil being operated in relay contacts are operated, whereby re-closing of the closure will not prevent the operation of said alarm means.

6. Apparatus according to claim 5, including a resistance and a capacitance connected to said first relay coil to provide a charging current path through said first relay coil to prevent said alarm means from being operated in response to an instantaneous actuation of said closure switch.

7. Apparatus according to claim '5, wherein said switch operator is a heating element and said timer switch responds to heat, said first relay coil is connected in series with said closure operated switch and said heating element across said source of power, said first relay contacts include a first stationary contact connected through said second relay contacts to supply power to said third relay coil, a second stationary contact connected to supply power to said second relay coil and also connected to supply power through said third relay'contacts to said heating element, and a movable contact con nected to said power source and being in contact with said first stationary contact in said first position and being in contact with said second stationary contact in said second position.

References Cited UNITED STATES PATENTS 2,250,828 7/1941 Foss 340276 3,070,784 12/1962 Strand 3l7.-139 X 3,200,393 8/1965 Worley 340-276 3,286,250 11/1966 Teitelbaum 340-276 JOHN W. CALDWELL, Primary Examiner P. PALAN, Assistant Examiner U.S. Cl. X.R.

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3757319A (en) * 1971-04-05 1973-09-04 Eaton Corp Security alarm system with bypass
US3794991A (en) * 1972-02-07 1974-02-26 Alarm Device Mfg Alarm system with timed exit circuit means
US3978475A (en) * 1975-05-29 1976-08-31 Westinghouse Electric Corporation Trouble indicator circuit for a security system
US3978477A (en) * 1975-05-29 1976-08-31 Westinghouse Electric Corporation Automatic test sequence circuit for a security system
US3978478A (en) * 1975-05-29 1976-08-31 Westinghouse Electric Corporation Reset circuit for a security system
US3978479A (en) * 1975-05-29 1976-08-31 Westinghouse Electric Corporation Solid state security system
US3990075A (en) * 1975-05-29 1976-11-02 Westinghouse Electric Corporation Solid state security system
US4064507A (en) * 1975-05-29 1977-12-20 Westinghouse Electric Corporation Noise generator circuit for a security system
FR2426947A1 (en) * 1978-05-25 1979-12-21 Seb Sa Antitheft alarm system for household security - has initial intermediate trigger stage activated by movement or e.g. window and uses bistable multivibrator coupled to XOR-gate
US4796010A (en) * 1986-07-28 1989-01-03 Bland Robert T Intrusion alarm and automatic illumination system
US20110018705A1 (en) * 2008-03-17 2011-01-27 Hochiki Corporation Alarm device
US20110025490A1 (en) * 2008-03-24 2011-02-03 Hochiki Corporation Alarm device
US20110057794A1 (en) * 2008-05-08 2011-03-10 Hochiki Corporation Alarm

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2250828A (en) * 1938-02-21 1941-07-29 Howton Radio Alarm Company Alarm system control
US3070784A (en) * 1960-10-27 1962-12-25 Robert J Strand Alarm system for parking meters
US3200393A (en) * 1962-06-18 1965-08-10 Emmett J Worley Electric burglar alarm system with exit and entry delay
US3286250A (en) * 1964-10-16 1966-11-15 Teitelbaum Menashe Burglar alarm utilizing bi-stable electronic switches

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2250828A (en) * 1938-02-21 1941-07-29 Howton Radio Alarm Company Alarm system control
US3070784A (en) * 1960-10-27 1962-12-25 Robert J Strand Alarm system for parking meters
US3200393A (en) * 1962-06-18 1965-08-10 Emmett J Worley Electric burglar alarm system with exit and entry delay
US3286250A (en) * 1964-10-16 1966-11-15 Teitelbaum Menashe Burglar alarm utilizing bi-stable electronic switches

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3757319A (en) * 1971-04-05 1973-09-04 Eaton Corp Security alarm system with bypass
US3794991A (en) * 1972-02-07 1974-02-26 Alarm Device Mfg Alarm system with timed exit circuit means
US3978475A (en) * 1975-05-29 1976-08-31 Westinghouse Electric Corporation Trouble indicator circuit for a security system
US3978477A (en) * 1975-05-29 1976-08-31 Westinghouse Electric Corporation Automatic test sequence circuit for a security system
US3978478A (en) * 1975-05-29 1976-08-31 Westinghouse Electric Corporation Reset circuit for a security system
US3978479A (en) * 1975-05-29 1976-08-31 Westinghouse Electric Corporation Solid state security system
US3990075A (en) * 1975-05-29 1976-11-02 Westinghouse Electric Corporation Solid state security system
US4064507A (en) * 1975-05-29 1977-12-20 Westinghouse Electric Corporation Noise generator circuit for a security system
FR2426947A1 (en) * 1978-05-25 1979-12-21 Seb Sa Antitheft alarm system for household security - has initial intermediate trigger stage activated by movement or e.g. window and uses bistable multivibrator coupled to XOR-gate
US4796010A (en) * 1986-07-28 1989-01-03 Bland Robert T Intrusion alarm and automatic illumination system
US20110018705A1 (en) * 2008-03-17 2011-01-27 Hochiki Corporation Alarm device
US9087444B2 (en) * 2008-03-17 2015-07-21 Hochiki Corporation Alarm device
US20110025490A1 (en) * 2008-03-24 2011-02-03 Hochiki Corporation Alarm device
US8493203B2 (en) * 2008-03-24 2013-07-23 Hochiki Corporation Alarm device
US20110057794A1 (en) * 2008-05-08 2011-03-10 Hochiki Corporation Alarm
US8514074B2 (en) 2008-05-08 2013-08-20 Hochiki Corporation Alarm

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