Transducer coupling
US4546651A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 2, 1984 |
| Grant date | Oct 15, 1985 |
| Priority date | — |
| Expiry date | Apr 2, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R27/26
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A circuit for coupling a transducer having a reactive sensing element to equipment providing either AC or DC drive voltage and equipped with strain gauge amplifiers in which the sensing impedance varies the gain of the feedback loop of an oscillator, an AGC circuit is coupled to the loop so as to derive a control signal related to the amplitude of oscillations therein and a gain control means is included in the loop that responds to the control signal in such manner as to restore the loop gain to unity after it has been changed therefrom by changes in the value of the sensing impedance. If the gain control means is a voltage divider having a variable resistor as the operative element, a matched variable resistor is used as the unbalancing element of a resistive bridge, and the values of the circuit are chosen such that the output signal from the bridge which may be applied to strain gauge amplifiers is linearly or desirably nonlinearly related to changes in the value of the reactive sensing impedance. Operating potentials for the oscillator are derived by a rectifier from the drive voltage. If the control signals is to be used as a linear output signal, the variable resistor of the…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.