Dual magnetic coil driver and monitor sensor circuit
US4712648A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 18, 1986 |
| Grant date | Dec 15, 1987 |
| Priority date | — |
| Expiry date | Aug 18, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/2013
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Sensor circuitry is disclosed for a transducer (32) having a sensor or delta coil (66) for generating a magnetic flux through a path of movement of a magnetically permeable piston member (48), such that movement of the member (48) changes the return coupled flux linkage, which flux change indicates movement of the member (48), and having a reference coil (84) spaced sufficiently from the path of movement of the member (48) such that movement of the latter has less affect on return coupled flux linkage of the reference coil (84) than the delta coil (66). The coils (66 and 84) are connected (204) in respective parallel voltage dividers, and a half-wave rectified AC signal (diode CR11) is applied thereto. A differential amplifier (210) senses the differential voltages across the coils and generates an output signal which is peak detected by an operational amplifier (212) and supplied to a further operational amplifier (214) for comparison against a reference input from the filtered, half-wave rectified AC signal for generating an error signal output which is then divided down as a reference input to a further operational amplifier (216) and is also delayed by charging an RC timing cir…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.