GB344674A - Improvements in or relating to burglar alarms - Google Patents

Improvements in or relating to burglar alarms

Info

Publication number
GB344674A
GB344674A GB8169/30A GB816930A GB344674A GB 344674 A GB344674 A GB 344674A GB 8169/30 A GB8169/30 A GB 8169/30A GB 816930 A GB816930 A GB 816930A GB 344674 A GB344674 A GB 344674A
Authority
GB
United Kingdom
Prior art keywords
asnieres
rheostat
microphones
class
disturbances
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
GB8169/30A
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.)
C E M A CONST ELECTRO MECANIQU
Original Assignee
C E M A CONST ELECTRO MECANIQU
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 C E M A CONST ELECTRO MECANIQU filed Critical C E M A CONST ELECTRO MECANIQU
Publication of GB344674A publication Critical patent/GB344674A/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

Landscapes

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

Abstract

344,674. Burglar alarms. C.E.M.A. CONSTRUCTIONS ELECTRO - MECANIQUES D'ASNIERES, 236, Avenue d'Argenteuil, Asnieres, Seine, France. March 13, 1930, No. 8169. Convention date, May 7, 1929, Addition to 339,863 [Class 118 (i), Indicators &c.] [Class 118 (i).] In a burglar alarm as described in the parent Specification, in order to distinguish normal noises occurring throughout the night from noises resulting from a prolonged attack on the walls or other parts of the building, a recording device is used to make a record of the normal nightly disturbances detected by the microphones, and the sensitiveness of the apparatus may be adjusted so as to eliminate the effect of such disturbances. For this purpose a rheostat may be arranged to work either in series with the microphones or as a potentiometer in the input circuit of the first valve. If the microphone circuit includes a step-up transformer for actuating the first valve grid, the rheostat may be placed as an adjustable shunt on the primary circuit.
GB8169/30A 1929-02-02 1930-03-13 Improvements in or relating to burglar alarms Expired GB344674A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR339863X 1929-02-02
FR586710X 1929-02-02

Publications (1)

Publication Number Publication Date
GB344674A true GB344674A (en) 1931-03-12

Family

ID=39885705

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8169/30A Expired GB344674A (en) 1929-02-02 1930-03-13 Improvements in or relating to burglar alarms

Country Status (1)

Country Link
GB (1) GB344674A (en)

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