Abstract: The invention relates to a plate orifice for a or in a measuring device for he flow metering of fluid streams, in particular gas streams, preferably for gas streams present in internal combustion engines, with the fluids, in particular the gases, being guided through at least one plate orifice (restrictor) disposed in a pipe and provided with a sharp edge definig its flow orifice, with a pressure sensor or a pressure measuring line of a differential pressure measuring device or of a differential pressure transducer disposed upstream as well as downstream of the plate orifice, the output signal of the differential pressure measuring device or the differential pressure transducer depending on the differential pressure forming the measuring signal for the fluid flow rate, in particular gas flow rate, through the plate orifice and optionally being fed to an evaluation unit. In plate orifices or measuring devices of this type, problems due to their contamination and their universal usability arise.

Abstract: In a level measuring device for electrically non-conductive liquids comprising a sensor which is positioned in a vessel and is in contact with the liquid, and further comprising an evaluation circuit connected to this sensor both compensation of a changing dielectric constant and a high degree of accuracy and resolution are achieved by placing a driver electrode 5 in the lower part of the vessel 1 at a position essentually coaxial to the sensor electrode 3, 4, and by placing a compensating electrode 6 between the driver electrode 5 and the wall 8 of the vessel 1, such that further capacitors are formed between the two electrodes 5 and 6 themselves as well as between them and the sensor electrode 3, 4 and between them and the wall 8 of the vessel 1.

Abstract: Capacitive measuring transformer, especially for small capacitance values, with two parallel bridge arms, connected with an oscillator, each of which has at least one capacitor, whereby a differential amplifier is provided which is connected on the input side with the bridge arms and the input of which is connected by a feedback circuit, containing passive elements only to one of the bridge arms. A control element (D.sub.1, D.sub.2) precedes every one of the bridge arms and a fixed potential or a potential changing inversely in relation the outlet of said differential amplifier, (OA.sub.1) is applied to the second bridge arm. As a result, one will moreover achieve a high measure of stability and linearity between capacitance and output voltage. The fixed potential is used when the feedback is to one bridge arm only. The potential changing inversely in relation to the output of the differential amplifier (OA.sub.

Abstract: A measuring circuit for use with an active polarized electrode, a reference electrode and a diaphragm which separates the solution to be examined from the electrolyte in which the electrodes are immersed. The output signals from the polarized electrode and from the reference electrode are processed as follows. The respective electrode is connected to one of the inputs of a respective operational amplifier (OA1, OA2) which serve as current voltage converters. The outputs of these amplifiers are then connected to a third operational amplifier (OA3) which detects the prevailing current difference in the electrode currents and initiates a necessary correction.