GB656366A - Improvements in or relating to apparatus responsive to the movement of a body relative to a detecting surface or surfaces - Google Patents

Improvements in or relating to apparatus responsive to the movement of a body relative to a detecting surface or surfaces

Info

Publication number
GB656366A
GB656366A GB53849A GB53849A GB656366A GB 656366 A GB656366 A GB 656366A GB 53849 A GB53849 A GB 53849A GB 53849 A GB53849 A GB 53849A GB 656366 A GB656366 A GB 656366A
Authority
GB
United Kingdom
Prior art keywords
triode
grid
valve
pulse
whose
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
GB53849A
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.)
ELECTRIC TIME RENTALS Ltd
Original Assignee
ELECTRIC TIME RENTALS 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 ELECTRIC TIME RENTALS Ltd filed Critical ELECTRIC TIME RENTALS Ltd
Priority to GB53849A priority Critical patent/GB656366A/en
Publication of GB656366A publication Critical patent/GB656366A/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

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
  • Geophysics And Detection Of Objects (AREA)

Abstract

656,366. Bridge circuits; indicating proximity of bodies. ELECTRIC TIME RENTALS, Ltd., and PHILLIPS, W. K. V. Jan. 7, 1949, No. 538. [Class 37] [Also in Group XXXVIII] A series fed audio-frequency Hartley oscillator operates with the tapped inductance 11 forming two arms of a bridge completed by variable resistor 12 and variable condenser 13 forming a third arm and connected to terminals 14, two detecting surfaces forming the fourth arm and defining a condenser whose capacitance value changes with approach of a body in the vicinity of the detecting surfaces to unbalance the bridge and produce an A.C. voltage across the output diagonal which is amplified by triode 15. The output of triode 15 is applied to anode bend detector 17 whose anode potential changes to produce an output whose A.C. component is byepassed and whose D.C. component is directed to the grid of triode 20 by long time constant circuit capacitor/resistor 21/22 so that triode 20 receives negative-going pulse and is blocked thereby and its anode potential rises. This occurrence drives the grid of the next triode 25 positive via junction of resistors 23/24 so that triode 25 is rendered saturably conductive and remains so until negative pulse on grid of valve 20 has leaked away, whereupon it reverts to blocked condition. Triode 25 is coupled to a further triode 26 by a short time constant circuit capacitor/resistor 27/28 which differentiates the output of valve 25 to direct a short negative pulse to grid of valve 26. This pulse has no effect, but when triode 25 reverts to non-conductive state the succeeding positive pulse effects energization of a relay coil 29 in the anode circuit of valve 26 and the relay contacts 30, 31 lock and an alarm or indicator connected to contacts 31 is thereby actuated. Contacts 30 are in series with a thermal delay switch 32 whereby the operator conditioning the apparatus for use has time to move away from the detecting surfaces before the relay contacts close.
GB53849A 1949-01-07 1949-01-07 Improvements in or relating to apparatus responsive to the movement of a body relative to a detecting surface or surfaces Expired GB656366A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB53849A GB656366A (en) 1949-01-07 1949-01-07 Improvements in or relating to apparatus responsive to the movement of a body relative to a detecting surface or surfaces

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB53849A GB656366A (en) 1949-01-07 1949-01-07 Improvements in or relating to apparatus responsive to the movement of a body relative to a detecting surface or surfaces

Publications (1)

Publication Number Publication Date
GB656366A true GB656366A (en) 1951-08-22

Family

ID=9706108

Family Applications (1)

Application Number Title Priority Date Filing Date
GB53849A Expired GB656366A (en) 1949-01-07 1949-01-07 Improvements in or relating to apparatus responsive to the movement of a body relative to a detecting surface or surfaces

Country Status (1)

Country Link
GB (1) GB656366A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3205352A (en) * 1961-08-04 1965-09-07 Gen Precision Inc Presence detector

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3205352A (en) * 1961-08-04 1965-09-07 Gen Precision Inc Presence detector

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