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:
Dec. 04, 1979
Filed:
Aug. 07, 1978
Richard A Dorman, Troy, NY (US);
Mechanical Technology Incorporated, Latham, NY (US);
Abstract
A controlled carrier current measuring sensor/transducer signal amplifier system comprising a carrier oscillator for providing a carrier voltage oscillatory signal of known frequency and fixed voltage magnitude. A differential amplifier has the carrier voltage oscillatory signal supplied to one of its inputs. A reference impedance and a variable impedance sensor transducer are connected in a series circuit across the output of the differential amplifier and a first feedback signal is fed back to a second input of the differential amplifier with the first feedback signal comprising the sum of the voltage across the reference impedance and the variable impedance sensor transducer. A buffer amplifier has its input connected to the juncture of the reference impedance and the variable impedance sensor/transducer for deriving an output voltage representative of the instantaneous value of the voltage across the variable impedance sensor/transducer. The output voltage signal from the output of the buffer amplifier is fed back to a third input to the differential amplifier in opposition to the first feedback signal for regulating the current supplied through the reference impedance and the variable impedance sensor/transducer to a substantially constant value whereby the output voltage signal from the output of the buffer amplifier provides a measure of the impedance of the variable impedance sensor/transduer. Preferably, the system further includes shielded conductors interconnected between the reference impedance and the variable impedance sensor/transducer and between the juncture thereof and the input to the buffer amplifier and the output from the buffer amplifier is fed back to the shielding of the shielded conductors whereby the effects of stray capacitance on any measurement obtained from the variable impedance sensor/transducer are minimized.