the most important parts of the energy supply device are a holding device 1 , a layer 2 of adjacently arranged transmitting coils 20 , and a layer 3 of adjacently arranged end devices 31 , 32 , 33 , 34 . the holding device 1 includes a rail 10 onto which the end devices 31 through 34 may be latched in a row , also with a gap 35 therebetween . the positioning of the end devices along the rail is free or flexible and does not require any particular sequence . the transmitting coils 20 are embodied in a screw shape or are helical with a cylindrical cover and an axis that extends parallel to the longitudinal extension of the holding device 1 . rectangular or elliptical screws may also be used . all such coil shapes are helical coils . in the exemplary embodiment depicted , six transmitting coils 20 are provided that may be turned on and off individually . their power supply lines are attached to the holding device 1 or pass therethrough , but are not shown . when the transmitting coils 20 are used for data signal transfer , the corresponding data lines are also provided . when the transmitting coils 20 may be switched individually , this means that they may also be interconnected in groups , as is shown for the end device 32 . a discrete electronics unit may be allocated to each individual transmitting coil to be able to regulate parameters of power output per individual coil , including current phase , current amplitude , and current frequency . the electronics unit may also include a sensor that detects coupling effects with associated receiving coils to determine which end device is adjacent or whether an end device can even be activated via the specific transmitting coil ( determines a gap in the row of end devices ). the transmitting coils are depicted without a core , but a non - closed core with an air gap could be present at the location at which one of the end devices is disposed . however , a ferrite structure 21 is usefully arranged to the side on the holding device 1 to prevent parasitic induction from the transmitting coils , which could interfere from sides of the holding device . in addition , eddy current losses are minimized in the possibly metal holding device . at least some of the end devices house a flat coil 30 that works as a receiving coil with the closest transmitting coil 20 . the windings of the flat receiving coil 30 run in a helical shape , wherein “ helical ” shall also be understood to include wound in a rectangle , printed , or in some other configuration , as fig2 illustrates . the receiving coil 30 surrounds a central opening and defines a plane whose perpendicular plane runs parallel or nearly parallel to the longitudinal extension of the holding device 1 . the portion h 1 of the field lines that runs horizontal in fig1 therefore crosses the receiving coil 30 and induces a voltage or current flow that may be used for supplying electrical energy to the end device affected . such a current flow may be interpreted as a data signal in the same manner . the reverse flow of information is also possible : the receiving coil 30 may also be switched as a transmitting coil to transfer data from the end device to the transmitting coils switched as receiving coils . in doing so , so - called “ load modulation ” may be used in which the receiving coil represents a varying load , which may be detected on the transmitting coil . for the end device 32 , three individual transmitting coils 20 are interconnected by using joint activation to create a virtual larger coil in order to make a common magnetic field available for the end device 32 . this may be used for instance for higher current consumption or to supply devices whose width exceeds the fit of the narrower end devices 31 , 33 . the transmitting coil at the gap 35 is switched without current if no end device is disposed there . however , locations without a transmitting coil may also be provided , as for the end device 34 , which does not have any active connection to the system or represents a reserve site . the system is not active here . feed voltage , for instance , or even data information may be passed further along the holding device via a bridge placed in the carrier rail . the drawing in fig2 depicts how the device having primary coil p 1 and secondary coil 51 may be constructed for transferring energy inductively . the holding device 1 forms a top hat rail 10 to which the end devices may be clipped adjacent to one another in a row . the housings ( not shown ) for the end devices are embodied in a u shape at their attaching ends and engage around the transmitting coils 20 in order to keep the receiving coils 30 as close as possible to the associated transmitting coils 20 . to this end the housings have clips ( not shown ). the housings for the end devices each accommodate at least one receiving coil 30 . the ferrite structure 21 provided for shielding is arranged in the hollow space of the top hat rail 10 . attached to the ferrite structure 21 is the transmitting coil 20 that generates magnetic field lines h 1 , h 2 , h 3 , h 4 ( fig3 ). the magnetic field lines h 1 , which are parallel to the holding device , cause energy to be added to the receiving coil 30 . the energy is made available to an electronics unit 51 that may be attached to a circuit board 50 . from the drawing in fig2 it may be clearly seen that the end devices may each clip to different locations along the rail 10 ( which is depicted shortened for the purposes of the drawing ). thus the end devices may be positioned at any location along the rail 10 . however , the ability of the receiving coil to be freely positioned has the drawback of weaker coupling between transmitting coil and receiving coil . resonance effects between transmitting coil and receiving coil are used to attain better energy transfer . this is explained using fig4 . a transmitting coil 20 and two receiving coils 30 a , 30 b are arranged in an inductive coupling without using a magnetic core , which is indicated by a field line h 1 . the transmitting coil 20 has a longer longitudinal extension than the receiving coils 30 a , 30 b , which are embodied as flat coils , so that a plurality of these flat coils may be arranged along the elongate transmitting coil 20 . power is supplied to the coil 20 via an alternating input voltage 22 . the receiving coils 30 a , 30 b are each disposed in a separate module , each with a load 41 , 42 that receives the energy output by the coil 20 . typically these loads each comprise a rectifier circuit , a smoothing capacitor , and an electronic circuit attached thereto . the transfer of energy between the transmitting coil 20 and the receiving coils 30 a , 30 b is particularly efficient when the circuits including the respective coils are resonant at a suitable frequency of the input voltage . each transmitting circuit with transmitting coil 20 and each receiving circuit with transmitting coil 30 a or 30 b has a resonance frequency that constitutes the inductances of the specific coils and the capacitances 43 , 44 , 45 . the capacitances also include capacitive coupling effects between the coil windings . to match the resonances to one another , each of the circuits may have discrete capacitors that are arranged in a series or parallel to the respective coils . combinations of series and parallel circuits are also possible to match the resonances . with the alignment of the resonance frequency to the working frequency of the alternating input voltage 22 , the system may be operated at increased efficiency . in addition to the useful inductivity , which is indicated by the field line h 1 , there is stray inductance , symbolized by the field lines h 2 , h 3 , h 4 . the good efficiency may be explained in that the energy of the stray fields of the coils 20 , 30 a , 30 b oscillates somewhat between the coil inductances and the capacitances 43 , 44 , 45 and is ideally not consumed . from the perspective of input voltage , the consumers 41 and 42 include almost only ohmic portions . to really be able to use the resonance effects , a regulating device ( not shown ) is allocated to each transmitting coil 20 and controls the current phase , current amplitude , and frequency of resonance with the coupled receiving coil 30 .