Kistler Holding Ag

Kistler Instrumente Ag

Leo Amstutz

Claudio Cavalloni

Paul Engeler

Adrian Hofmann

David Cornu

Max P Waser

Daniel Otter

Roman Strebel

Kurt Neff

Bruno Busser

An electronic circuit that changes a charge signal into a voltage signal within a sensor suitable for direct installation in a roadway can be connected to two single-core cables that need not be highly insulating yet can realize the required power supply of the electronics. The circuit includes an integrated impedance converter (IEPE) at the output to a two-core cable and a charge amplifier with an ICthat has two inputs. A capacitor Cc is connected in series to the signal output of the sensor at one input of the IC. A Zener diode D is arranged between the ground output of the sensor and the second input of the ICand can be supplied with power by a resistor Rin conjunction with a power supply arranged on the output side in order to adapt the potential at the second input of the IC

Charge to voltage conversion circuit for WIM sensor and WIM sensor with same

A circuit for a charge amplifier for converting piezoelectric measurement signals continuously sets the output signal of the amplifier to a value close to zero, such that a reset switch becomes unnecessary. The amplifier includes a pulse generator that provides the output signal of the amplifier in the form of pulses, which are easy to transmit with low interference. The pulse frequency is proportional to the rate of change of charge. The pulses, which are added in a counter, represent a value proportional to the change in the charge since the last counter reset, which is proportional to the present measured value at the measurement element.

Digital charge amplifier and method for converting charge signals into digital signals

A measuring system includes a piezoelectric sensor, two or more charge amplifiers that are provided with different amplification settings and one respective output, and a signal splitter which is disposed between the sensor and the amplifiers. A charge signal received by the piezoelectric sensor is subdivided into two or more partial signals on the signal splitter during a measurement, and each of two or more partial signals is fed to one of the charge amplifiers, is processed therein, and is finally fed to the outputs. The signal splitter preferably encompasses two or more capacitors. The inventive measuring system is used above all for measuring forces, pressures, extensions/expansions, moments, or accelerations.

Measuring system comprising variably sensitive outputs

A charge amplifier circuit includes an operational amplifier with an integrating capacitor between its inverting input and its output, and a resetting device with a switch that is closed during the reset phase for discharging the integrating capacitor. Provided at the output of the charge amplifier circuit is a circuit arrangement with a correction amplifier which when the switch is closed, automatically delivers a correction charge to the integrating capacitor, compensating the zero shift of the output voltage from the charge amplifier circuit during the measuring phase. This circuit arrangement is particularly suited for charge amplifiers with an extremely high ohmic input stage.

Charge amplifier circuit

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Neftenbach, Switzerland

Leo Amstutz