Abstract: A measurement circuit in the output circuit of a sensor detects the polarity of a source to which a load is connected. The detection of one of the two polarities establishes one of two states which is stored in a storing element and the correct one of two drivers is switched to the output terminals. This state is maintained for as long as there is no change to the polarity at the output terminals. If the terminals are interchanged, then the measurement circuit correctly restores the stored state, so that the correct driver is associated with the load in each case. If positive instead of negative switching sensors are required, there is no need to replace the equipment. When the voltage is turned on, the equipment is initialized, so that it is set in accordance with the new circumstances.

Abstract: The identification system operates by the contactless, inductive transmission of information via oscillatory circuits coupled by an electromagnetic field. Excitation is produced by pulses representing the information; the pulse response is utilized. The associated apparatus has one or more pairs of oscillatory circuits (A1/B1;A2/B2;A3/B3) and means (21, 22, 23) for processing the pulse response. A position recognition process transmits test information which is used for the sequential short-circuiting of an oscillatory circuit on the receiver side. This oscillatory circuit behaves like a damped/undamped body as a function of the test function. The partner oscillatory circuit on the transmitter side is excited at, for example, twice the frequency of the test frequency and its pulse response contains the test function through the defined damping behaviour. If the test function is again recognized as a result, the connection is correct and write or read operation is released.

Abstract: The process for the detection of an eddy current-induced body in the action range of an inductive resonant circuit component (L) uses in place of a continuous operation and detection of the current change, a network containing a resonant circuit (L,C) is briefly excited with an electric function and the system response of the network is evaluated. The proximity sensor is constituted by an oscillatable network (L,C) operated on the input side with a function generator and, on the output side, the system response is investigated with an evaluation circuit.