GB1333584A - Alarm systems - Google Patents
Alarm systemsInfo
- 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
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.
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)
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 |
-
1971
- 1971-08-27 GB GB1333584D patent/GB1333584A/en not_active Expired
Cited By (2)
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 |