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:
Jul. 26, 1977
Filed:
Jul. 19, 1976
Edwin Langberg, Cherry Hill, NJ (US);
Other;
Abstract
A replica bridge sensing circuit, comprising an amplifier having inverting and non-inverting inputs, which are symmetrically connected to a generator through a bridge circuit that has replica elements in corresponding branches. Replica elements are defined as circuit components which because of identity of the manufacturing process, are nearly identical both physically and electrically. A nearly balanced replica bridge, so connected, between the input and the output of such an amplifier forms a Replica Bridge Oscillator (RBO) circuit. Non-linear elements are included in the oscillator circuit to stabilize the amplifier output amplitude and the phase angles between the inputs and output. Replica Bridge Oscillator operation is substantially immune to changes in environmental conditions and to changes in the power supply voltages. With replica sensor elements used in corresponding branches, the Replica Bridge Oscillator is a sensing circuit particularly well adapted for use in detection of small sensor impedance variations. When utilized for metal detection, such a sensing circuit exhibits improved sensitivity and stability over existing detection circuits and is particularly adapted for multiaxial operation.