The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 20, 1978
Filed:
Dec. 01, 1976
Applicant:
Inventor:
Paul Anthony Spencer, London, EN;
Assignee:
Arado Electronics, London, EN;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G01V / ;
U.S. Cl.
CPC ...
324-3 ; 324233 ; 324239 ;
Abstract
A metal detector has a balanced coil arrangement fed by an audio frequency oscillator. In-phase and quadrature components arising when the arrangement is unbalanced by proximate conductive objects are detected, the sense of the quadrature component depending on whether the object is ferromagnetic or non-ferromagnetic. The quadrature component varies the frequency of another audio frequency oscillator above and below a mean value and the in-phase component controls the strength of the audio frequency signal fed from the second oscillator to a transducer such as headphones.