GB1453669A - Sealed envelope examining device - Google Patents

Sealed envelope examining device

Info

Publication number
GB1453669A
GB1453669A GB2425674A GB2425674A GB1453669A GB 1453669 A GB1453669 A GB 1453669A GB 2425674 A GB2425674 A GB 2425674A GB 2425674 A GB2425674 A GB 2425674A GB 1453669 A GB1453669 A GB 1453669A
Authority
GB
United Kingdom
Prior art keywords
circuit
metal
base
letters
drawer
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
GB2425674A
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.)
Kulik H S
Original Assignee
Kulik H S
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 Kulik H S filed Critical Kulik H S
Publication of GB1453669A publication Critical patent/GB1453669A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
    • G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
    • G01V3/10—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils
    • G01V3/104—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils using several coupled or uncoupled coils
    • G01V3/105—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils using several coupled or uncoupled coils forming directly coupled primary and secondary coils or loops

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Electromagnetism (AREA)
  • Environmental & Geological Engineering (AREA)
  • Geology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Geophysics (AREA)
  • Emergency Alarm Devices (AREA)
  • Geophysics And Detection Of Objects (AREA)

Abstract

1453669 Metal detectors H S KULIK and J SCHACHTER 31 May 1974 [28 Feb 1974] 24256/74 Heading G1N A device for sensing metal in "letter bombs" comprises a base unit housing the detector circuit and one sensor coil and a second coupled coil supported on a bridge structure above the base. Letters may be placed in a drawer slidable on the base beneath the bridge Figs. 1 and 5 (not shown), or the device may be inclined on a wire support for letters to slide down Fig. 6 (not shown). A hinged cover is provided with a transverse bar to hold the drawer in the closed position. CIRCUIT:- As described Fig. 7 (not shown) the coils are connected in a transistor oscillator circuit whose amplitude varies when metal disturbs the coupling between them. The variation triggers a thyristor alarm circuit.
GB2425674A 1974-02-28 1974-05-31 Sealed envelope examining device Expired GB1453669A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US446698A US3893022A (en) 1974-02-28 1974-02-28 Sealed envelope examining device for detecting the presence of metal

Publications (1)

Publication Number Publication Date
GB1453669A true GB1453669A (en) 1976-10-27

Family

ID=23773535

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2425674A Expired GB1453669A (en) 1974-02-28 1974-05-31 Sealed envelope examining device

Country Status (2)

Country Link
US (1) US3893022A (en)
GB (1) GB1453669A (en)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USD255783S (en) 1977-12-21 1980-07-08 Hays Ronald B Letter bomb detector
US4266193A (en) * 1978-09-11 1981-05-05 Most Lynn W Means for detecting metal objects
US4883264A (en) * 1987-11-02 1989-11-28 Laurel Bank Machines Co., Ltd. Bill disbursing system
US5316857A (en) * 1988-12-03 1994-05-31 Deutsche Aerospace Airbus Gmbh Sheet material having a recognition enhancing feature
AU626577B2 (en) * 1989-02-17 1992-08-06 Bell Helicopter Textron Inc. Method for detecting protective layer on composite materials
AT349U1 (en) * 1994-05-03 1995-08-25 Tkadletz Herbert Dipl Ing Mag PROTECTIVE DEVICE AGAINST THE EXPLOSION EFFECT OF BOMBS
US6420866B1 (en) * 1998-09-21 2002-07-16 Reliance Electric Technologies, Llc Apparatus and method for detecting metallized containers in closed packages
US6339331B1 (en) * 1999-12-14 2002-01-15 General Electric Company Methods and apparatus for inspecting TV-shaped openings, using eddy current

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2966582A (en) * 1957-01-11 1960-12-27 Wachtel Kurt Railroad signalling

Also Published As

Publication number Publication date
US3893022A (en) 1975-07-01

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Legal Events

Date Code Title Description
PS Patent sealed [section 19, patents act 1949]
PCNP Patent ceased through non-payment of renewal fee