Electrical measurement circuit including a low-pass filter, in particular for weighing
US4531600A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 30, 1983 |
| Grant date | Jul 30, 1985 |
| Priority date | — |
| Expiry date | Nov 30, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01G23/10
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A link of controllable resistance comprising an FET (Q16) connected in series with a low-value resistor (R15) is connected in parallel with a time constant determining resistance (R11) in an RC type low-pass filter. A discriminator circuit (40, 50, 60) provides an on/off type signal following variations in the DC component of an input signal present on a terminal (A). A retriggerable monostable (80) defines a "neutral" time interval of predetermined duration running from the beginning of said on/off signal. At the end of said neutral period, a circuit (20) switches the FET on, thereby reducing the time constant of the RC network in the RC low-pass filter. This time constant is subsequently progressively rasied to a high value by progressively switching the FET off. The filter is specially applicable to weighing a body that is subjected to movement or to oscillation, or to performing weighing measurements in a vibrating environment.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.