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GB1427565A - Burglar alarms - Google Patents

Burglar alarms

Info

Publication number
GB1427565A
GB1427565A GB1080573A GB1080573A GB1427565A GB 1427565 A GB1427565 A GB 1427565A GB 1080573 A GB1080573 A GB 1080573A GB 1080573 A GB1080573 A GB 1080573A GB 1427565 A GB1427565 A GB 1427565A
Authority
GB
United Kingdom
Prior art keywords
magnet
safe
switch
block
unit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB1080573A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
American District Telegraph Co
Original Assignee
American District Telegraph Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by American District Telegraph Co filed Critical American District Telegraph Co
Publication of GB1427565A publication Critical patent/GB1427565A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H36/00—Switches actuated by change of magnetic field or of electric field, e.g. by change of relative position of magnet and switch, by shielding
    • H01H36/0006—Permanent magnet actuating reed switches
    • H01H36/0046—Limit switches, also fail-safe operation or anti-tamper considerations
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G08B13/02—Mechanical actuation
    • G08B13/08—Mechanical actuation by opening, e.g. of door, of window, of drawer, of shutter, of curtain, of blind

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Burglar Alarm Systems (AREA)

Abstract

1427565 Burglar alarms AMERICAN DISTRICT TELEGRAPH CO 6 March 1973 [8 March 1972] 10805/73 Heading G4N [Also in Division H1] A burglar alarm switch has an actuating block 16, containing a permanent magnet 20, and a second block 17 containing two magnetic change-over contact units SW1, SW2 and a magnetic shield 29 arranged so that the magnet does not influence unit SW2 which will however be operated if an additional magnetic field is used in an effort to defeat the alarm. The shield 29 is mounted on the casing 27 (preferably of aluminium) of the block 17 for removal if the casing is removed and the magnetic material of the safe 10 on which the switch is mounted may be such as to change the effect of the magnet 20 on unit SW1 if the switch blocks are removed together from the safe 10. The blocks 16, 17 may be mounted on relatively rotatable parts 13, 14 of the safe door which requires such rotation before opening. Fig. 6 shows the position of the contact units SW1 and SW2 with the magnet influencing SW1 only. Should either unit be operated their series circuit will first be open circuited, to cause a low current sensitive detector 44 to operate, and then earthed through a conductor 55 to cause a high current sensitive detector 45 to operate.
GB1080573A 1972-03-08 1973-03-06 Burglar alarms Expired GB1427565A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US23287172A 1972-03-08 1972-03-08

Publications (1)

Publication Number Publication Date
GB1427565A true GB1427565A (en) 1976-03-10

Family

ID=22874940

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1080573A Expired GB1427565A (en) 1972-03-08 1973-03-06 Burglar alarms

Country Status (3)

Country Link
US (1) US3771153A (en)
CA (1) CA998134A (en)
GB (1) GB1427565A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2450890A (en) * 2007-07-10 2009-01-14 Elmdene Internat Ltd Magnetic contact
GB2453591A (en) * 2007-10-12 2009-04-15 Elmdene Internat Ltd Magnetic contact

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3896427A (en) * 1974-06-27 1975-07-22 James P Campman Magnetically operated alarm
US4544903A (en) * 1983-11-17 1985-10-01 Pittway Corporation Electrical connector system
US4593491A (en) * 1984-01-31 1986-06-10 The United States Of America As Represented By The United States Department Of Energy Alarm sensor apparatus for closures
DE3409649C1 (en) * 1984-03-16 1985-11-07 Heinrich 3550 Marburg Sälzer Device for displaying the movement and / or position of a shut-off device
CN1232995C (en) * 2001-10-24 2005-12-21 李文丰 Enclosed electrical switch assembly
US7355515B2 (en) * 2005-09-23 2008-04-08 Honeywell International, Inc. Magnetic security device for securing doors
CN103903407B (en) * 2014-04-10 2016-06-22 宁波宇宏电气有限公司 Private network warning system for inspection well cover breakage, quilt
CN121142412A (en) * 2024-06-14 2025-12-16 东莞令特电子有限公司 Directional activation reed sensor

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2877361A (en) * 1957-04-12 1959-03-10 Holmes Electric Protective Com Burglar alarm system
US2912540A (en) * 1958-02-13 1959-11-10 American District Telegraph Co Defeat resistant burglar alarm contact
US3161742A (en) * 1961-08-24 1964-12-15 Specialties Dev Corp Magnetic intruder and fire deterctor
US3444493A (en) * 1966-08-29 1969-05-13 Ca Atomic Energy Ltd Magnetically operated reed switch assembly
CH473467A (en) * 1967-04-27 1969-05-31 Balanciers Reunies Sa Device for controlling at least one contact by magnetic means
US3544934A (en) * 1969-05-08 1970-12-01 American Mach & Foundry Proximity switch-type control means

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2450890A (en) * 2007-07-10 2009-01-14 Elmdene Internat Ltd Magnetic contact
GB2450890B (en) * 2007-07-10 2011-12-14 Elmdene Internat Ltd Magnetic contact
GB2453591A (en) * 2007-10-12 2009-04-15 Elmdene Internat Ltd Magnetic contact
GB2453591B (en) * 2007-10-12 2012-08-29 Elmdene Internat Ltd Magnetic contact

Also Published As

Publication number Publication date
CA998134A (en) 1976-10-05
US3771153A (en) 1973-11-06

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Legal Events

Date Code Title Description
PS Patent sealed [section 19, patents act 1949]
PCNP Patent ceased through non-payment of renewal fee