GB640929A - Device for the protection of enclosed premises - Google Patents

Device for the protection of enclosed premises

Info

Publication number
GB640929A
GB640929A GB1686447A GB1686447A GB640929A GB 640929 A GB640929 A GB 640929A GB 1686447 A GB1686447 A GB 1686447A GB 1686447 A GB1686447 A GB 1686447A GB 640929 A GB640929 A GB 640929A
Authority
GB
United Kingdom
Prior art keywords
receiver
transmitter
alarm
relay
pentode
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
GB1686447A
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.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Priority to GB1686447A priority Critical patent/GB640929A/en
Publication of GB640929A publication Critical patent/GB640929A/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
    • G08B13/24—Electrical actuation by interference with electromagnetic field distribution
    • G08B13/2491—Intrusion detection systems, i.e. where the body of an intruder causes the interference with the electromagnetic field

Landscapes

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

Abstract

640,929. Burglar and like alarms. GRIESSER, W. June 26, 1947, No. 16864. Drawings to Specification. [Class 118 (i)] A device for the protection of enclosed premises comprises an ultra-short wave radio transmitter radiating an audio-frequency modulated directional beam which is received by a directional receiver and causes a relay under control of the receiver to be held in its non- alarm position. Transmitter and receiver circuits are described and illustrated in Figs. 1 and 2 respectively (not shown). The transmitter consists of a triode A.F. oscillator modulating a triode R.F. oscillator directly coupled to an aerial. The receiver consists of a diode detector stage, a triode-pentode twostage amplifier and a further diode arranged to rectify the A.F. to give a positive control voltage on the grid of a final pentode (biassed to class C operation) causing it to pass current through a relay in its anode circuit and thereby hold alarm contacts open. If the radio beam is interrupted, by a burglar for example, the receiver detects no A.F., the positive control voltage ceases and the final pentode cuts off, thereby releasing the relay which closes the alarm contacts. On restoration of the signal the alarm relay is not automatically reenergized since on release it breaks its own circuit and the alarm will continue until the device is reset by depressing a push-button which bridges the relay " hold " contacts. A separate source of power, e.g. an accumulator battery, is provided for the alarm which will then also operate if the mains supply fails or the transmitter or receiver are damaged. The aerials of both transmitter and receiver comprise tuned coils arranged in front of reflectors enabling the apparatus to be made in totally enclosed units, the emitting and receiving sides being closed by highly insulating material. The tuning may be achieved by wing members pivotally mounted on the reflectors. The transmitter and receiver each contain their' own power packs but the transmitter may have its rectifier and modulator omitted and be fed by raw A.C.
GB1686447A 1947-06-26 1947-06-26 Device for the protection of enclosed premises Expired GB640929A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1686447A GB640929A (en) 1947-06-26 1947-06-26 Device for the protection of enclosed premises

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1686447A GB640929A (en) 1947-06-26 1947-06-26 Device for the protection of enclosed premises

Publications (1)

Publication Number Publication Date
GB640929A true GB640929A (en) 1950-08-02

Family

ID=10085067

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1686447A Expired GB640929A (en) 1947-06-26 1947-06-26 Device for the protection of enclosed premises

Country Status (1)

Country Link
GB (1) GB640929A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3163861A (en) * 1962-05-02 1964-12-29 Suter Henry Electromagnetic field disturbance intruder detection apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3163861A (en) * 1962-05-02 1964-12-29 Suter Henry Electromagnetic field disturbance intruder detection apparatus

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