Abstract: The inductive flow meter and method of exciting a coil includes a coil with unipolar excitation, which generates exciting pulses having a pulse interval therebetween. The length of the pulse interval is shorter than that of an exciting pulse. The associated evaluation circuit includes two alternately clocked channels whose evaluation phases overlap each other in time, the measuring voltage being obtained at the ends of the signal paths by alternately sampling the channels.

Abstract: The inductive flow meter and method of exciting a coil includes a coil with unipolar excitation, which generates exciting pulses having a pulse interval therebetween. The length of the pulse interval is shorter than that of an exciting pulse. The associated evaluation circuit includes two alternately clocked channels whose evaluation phases overlap each other in time, the measuring voltage being obtained at the ends of the signal paths by alternately sampling the channels.

Abstract: In an inductive flow meter, the magnetic field generator that generates a magnetic field within a tube, is connected to a source of alternating voltage via an electronic switch. The switch is controlled such that it becomes conductive only upon a zero crossing of the alternating voltage, respectively, and remains conductive until the next successive zero crossing of the exciting current. The useful voltage taken at the electrodes is integrated in an integrator, whereby the parasitic voltage coupled into the electrode loop by self induction becomes zero. In order to eliminate the influences of retentivity, each current pulse, at which integration is performed, is preceded by a pre-pulse.

Abstract: In an inductive flow meter, the magnetic field generator (11), provided for generating a magnetic field within a tube (10), is connected to a alternating current voltage source via an electronic switch (13). The switch (13) is controlled in such a manner that it becomes conducting only at a zero crossing of the alternating current, respectively, and subsequently remains in the conducting state until the next zero crossing of the exciting current (i) occurs.

Abstract: The circuit comprises two scanning/holding circuits (SH1, SH2), one of which (SH1) scanning the input signal during the positive half-wave, and the other (SH2) scanning the input signal during the negative halfwave. The output signals (U.sub.4, U.sub.5) of the scanning/holding circuits are summed up in a summing device (A) and are fed back to the input of the second amplifier (V.sub.2) which receives the intelligence signal. By this feedback of the summed anti-phase direct current signals (U.sub.4, U.sub.5), overlaid momentary and stationary disturbance voltages are reduced, whereas the intelligence signal is amplified by the full gain (.mu.) of the second amplifier (V.sub.2).

Abstract: A device for the magneto-inductive measuring of the flow rate of a liquid medium is disclosed wherein a cylindrical probe is immersed in a tube or in an open channel. The probe contains a cylindrical measuring channel through which flows the fluid to be measured. The probe includes a coil, which generates a magnetic field that extends through the measuring channel and whose axis is normal to the direction of fluid flow. Electrodes are mounted on the wall of the measuring channel, from which a voltage may be taken that is proportional to the flow rate of the fluid.

Abstract: In this inductive flow meter a pair of electrodes are disposed on opposite sides of a tube through which flows the fluid being measured. A magnetic field is generated across the tube, the strength of which increases and decreases linearly with time. The voltage developed across the electrodes is scanned by first and second sample and hold circuits operative respectively near the beginning and near the end of each increasing or each decreasing branch of the magnetic field cycle. A difference circuit obtains the mean value of the difference between the sampled voltages; this value very accurately indicates the flow rate, since the described circuitry compensates for various system error voltages.