GB1333584A - Alarm systems - Google Patents

Alarm systems

Info

Publication number
GB1333584A
GB1333584A GB1333584DA GB1333584A GB 1333584 A GB1333584 A GB 1333584A GB 1333584D A GB1333584D A GB 1333584DA GB 1333584 A GB1333584 A GB 1333584A
Authority
GB
United Kingdom
Prior art keywords
impedance
wires
sensing
alarm
aug
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
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.)
Emerson Process Management Ltd
Original Assignee
Rosemount Engineering Co Ltd
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 Rosemount Engineering Co Ltd filed Critical Rosemount Engineering Co Ltd
Publication of GB1333584A publication Critical patent/GB1333584A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G08B13/22—Electrical actuation
    • G08B13/26—Electrical actuation by proximity of an intruder causing variation in capacitance or inductance of a circuit
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/06—Electric actuation of the alarm, e.g. using a thermally-operated switch

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Burglar Alarm Systems (AREA)

Abstract

1333584 Alarm systems ROSEMOUNT ENG CO Ltd 27 Aug 1971 [27 Aug 1970] 41355/70 Heading G4N An alarm system comprises a pair of wires 13, 14 fed with alternating potential with respect to a reference point 23 and a pair of diodes 15, 16 of opposite polarity for supplying A.C. from the wires 13, 14 to a sensing impedance 17 and means 11, 24 for monitoring changes in the D.C. in the wires 13, 14. In a burglar alarm, the sensing impedance 17 may be the capacitance of a length of wire attached to a wall or floor. In the balanced system shown in Fig. 1, two sensing impedances 17 and 20 are employed, the D.C. signal at D, F being normally zero but, in the presence of an intruder, the polarity indicates which impedance 17, 20 is being approached. An RF source 10 may be employed. Fig. 3 shows the circuit in block 11. The system is applicable to vehicles or boats. If impedance 17 is inductive, it may be changed by means of a metal plate attached to a door or operated by a bimetallic strip in a fire alarm system. Impedance 17 may alternatively be a resistor or capacitor having a large temperature coefficient.
GB1333584D 1971-08-27 1971-08-27 Alarm systems Expired GB1333584A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB4135570 1971-08-27

Publications (1)

Publication Number Publication Date
GB1333584A true GB1333584A (en) 1973-10-10

Family

ID=10419310

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1333584D Expired GB1333584A (en) 1971-08-27 1971-08-27 Alarm systems

Country Status (1)

Country Link
GB (1) GB1333584A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4222045A (en) * 1979-05-04 1980-09-09 Firetek Corporation Capacitive shift fire detection device
GB2253084A (en) * 1991-02-19 1992-08-26 Chiu Yia Kong Burglar alarm

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4222045A (en) * 1979-05-04 1980-09-09 Firetek Corporation Capacitive shift fire detection device
GB2253084A (en) * 1991-02-19 1992-08-26 Chiu Yia Kong Burglar alarm

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Legal Events

Date Code Title Description
PS Patent sealed
PLNP Patent lapsed through nonpayment of renewal fees