An electrical plug connector for connection of an electrical cable (2) to an apparatus, such as a sensor or an actuator, includes a housing (3) having a contact mount (5) holding a variety of contacts (4), and an electronics circuit (6) having at least one light-emitting element, LED (7) and being electrically connected to the contacts (4). The status of whether the LED (7) is illuminated or not can be identified particularly well, even in the presence of strong external incident light, by the housing (3) being composed of a thermoplastic material, at least in the area of the LEDs (7), and including an additive (8) that influences transparency and color for reducing the transparency of the thermoplastic material.

An oscillator circuit for a sensor, with a tuned circuit and an operational amplifier, the electrical oscillation of the tuned circuit is capable of being tapped between a first terminal and a second terminal of the tuned circuit, and the first terminal of the tuned circuit being connected to the noninverting input of the operational amplifier and the output of the operational amplifier is fed back to the noninverting input of the operational amplifier. The oscillator circuit is designed to improve the dynamic behavior of the oscillator circuit by the second terminal of the tuned circuit --at least in terms of AC voltage --being directly connected to the inverting input of the operational amplifier.

An inductive proximity switch with a housing formed of a nonmagnetic, high-grade steel, with a transmitting coil, two receiving coils which are connected in series in opposite directions and which are located symmetrically relative to the transmitting coil, and an evaluation circuit which is connected to the receiving coils. At a given size, the inductive proximity switch has a relatively large operating distance and the operating distance is largely stable, especially is largely independent of temperature, essentially in that, on the back of the receiving coils, opposite the influence side, there is a pre-damping element and the pre-damping properties of the pre-damping element at least approximately correspond to the pre-damping properties of the housing on the influence side.

An electronic switching device, which operates without contact, includes a single sensor element (1), a clock generator, which can be provided internally or which can be connected externally, an evaluation circuit (2), and an electronic or electromechanical switch (3), which is provided on an output side. The evaluation circuit (2) includes diversity processing units (4, 5), and a checking unit (6), wherein an output signal of the sensor element (1) is delivered in succession to the processing units (4, 5), and that output signals of the processing units (4, 5) are checked for consistency by the monitoring unit (6). Advantageously, with only a single sensor element (1), category 4 of EN 954-1 or safety level SIL 3 of EN 61508 requirements can be achieved.

A device for measurement and detection of the level of a medium in a container with a sensor element, with a reference element and an electrical circuit which contains at least one AC voltage source and an evaluation unit, the sensor element and the reference element being arranged such that the medium to be measured or detected influences the impedance between them. The capacitive level measurement and detection device has an AC voltage source that supplies a high-frequency voltage or a voltage with high frequency voltage portions. The circuit which has the AC voltage source, the sensor element and the reference element has an impedance which is as low as possible. The electrical circuit can have an amplifier, a timer, a pulse shaper, a first synchronous rectifier, a first I/U converter, a microcontroller, a reference impedance, a second synchronous rectifier and a second I/U converter.