1
Frank Kuhnel: Circuit arrangement for the electrothermal measurement of level. VDO Adolf Schindling, Martin A Farber, October 28, 1986: US04619140 (18 worldwide citation)

In a circuit arrangement for the electrothermal measurement of level with a resistance sensor (1) which can be fed by a source of constant current (3), a flow-of-operation control (12) for timed operation of the circuit arrangement in scanning periods is provided. By the flow-of-operation control th ...


2
Frank Kuhnel: Device for the capacitive measurement of the filling level of fluid to a container. VDO Adolf Schindling, Martin A Farber, December 6, 1983: US04418569 (17 worldwide citation)

A device for the capacitive measurement of a level of filling having a measurement capacitor which dips into the fluids to be measured in accordance with the filling level thereof, and a unit for forming an electric value corresponding to the filling level and a unit for compensating for different d ...


3
Frank Kuhnel: Circuit for electrothermal level measurement compensated for ambient temperature. VDO Adolf Schindling, Martin A Farber, December 30, 1986: US04633491 (11 worldwide citation)

In a circuit for electrothermal measurement of level compensated for ambient temperature which has a switched source of constant current (2) for a resistance probe (1), a first variable formed from an initial voltage U.sub.0 on the resistance probe at the start of a heating period is compared by a c ...


4
Frank Kuhnel: Device for electrically monitoring the level of a liquid present in a container. VDO Adolf Schindling, Martin A Farber, August 21, 1984: US04466282 (8 worldwide citation)

In a device for electrically monitoring the level of a liquid present in a container, a plurality of temperature-dependent resistance probes (n-1, n, n+1) are arranged at different heights in the container, they being adapted to be connected one after the other to a source of constant current (5) un ...