Automatic offset control for constant temperature anemometer
US5493906A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 1, 1994 |
| Grant date | Feb 27, 1996 |
| Priority date | — |
| Expiry date | Jun 1, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01P5/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An electrical control circuit for a constant temperature anemometer includes a first operational amplifier coupled to receive inputs from two intermediate terminals of the Wheatstone bridge, and to generate an output voltage in response to a difference in voltage between the intermediate terminals. A second operational amplifier receives the output voltage, and provides its output as a drive voltage to the Wheatstone bridge. The second operational amplifier also provides its output to a feedback loop which incorporates an A/D converter, a digital processor and a D/A converter. The amplifier analog output is converted to a digital signal. The digital processor calculates a digital offset value, based on a constant ratio of the digital offset value/digital signal, predetermined by selection and setting of the various control circuit components. The D/A converter converts the digital offset value to an offset voltage provided to the second operational amplifier as an input. Thus, the second amplifier output is continuously and automatically modified by the appropriately calculated offset voltage, which leads to circuit stability and reliability over a much wider frequency bandwidth.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.