Abstract: A telephone station (1) having a handset (14) can be connected to a telephone exchange (5) by means of first and second switches (6, 7) by way of two lines (2, 3). When the switches (6, 7) are closed the telephone station (1) can be supplied with electrical energy from the telephone exchange (5) by way of the lines (2, 3). Within the telephone station (1) the first switch (6), a first coil (8), a circuit member (10), a second coil (9) and the second switch (7) are electrically connected in series. The switches (6, 7) are actuable by the handset (14) of the telephone station (1). The two coils (8, 9) are wound in opposite directions around a body (12) of magnetic material.

Abstract: A Hall element has a polygonal plane cross-section. In the cross-sectional plane, on the sides of the cross-section, are cross-sections of electrodes, the number of which is a multiple of four. The locations and cross-sections of the electrodes are mathematically conformal mappings into the polygonal plane cross-section of a fictitious group of non-overlapping cross-sections of electrodes in equal number transformed from a fictitious plane in which they are arranged radially symmetric on the circumference of a circle. The radius of the circle is equal to one. The fictitious group is sub-divided into groups of four within which the cross-sections of the corresponding fictitious electrodes are always at the same distances to each other on the circumference of the circle.