the electrode 50 is usually in the range 1 100 pf such a change leads to a relevant change in the oscillator frequency for example to a change between 0 1 and 10 khz the evaluation device is constructed in such a way that it can detect the change in the oscillator frequency and thus it can recognize an approach of an object 60 particularly of a living being to the electrode 50 the approach of a living being 60 is schematically shown with a hand in fig1 where through the approach to the server electrode 50 the field radiated by this is partially absorbed by the object 60 which leads to a change in the capacitive environment of the server electrode 50 for example the evaluation device 40 can be constructed in such a way that the frequency change of the signal generated by the lc oscillator can be compared with a reference signal which for example is generated by a quartz stabilized oscillator the comparison of the frequency of the oscillator signal with the frequency of the reference signal can take place with various means known in the prior art however the quartz stabilized oscillator can also be used as a cycle for a counter in which the counter measures the frequency of the oscillator signal within a predetermined number of cycles with measurements following each other over time within several time intervals of equal cycle length it is possible to determine whether the frequency of the oscillator signal changes or not on the basis of the structure of the server circuit according to the invention with a generator and lc series resonant circuit temperature induced frequency changes in the server circuit can be efficiently.