When designing power electronic circuits often electromagnetic properties of layout and construction prevent a proper function. The Know-How for creating working circuits is up to now not well described in textbooks and has to be learned individually by all engineers starting with power electronics. Normally this is accompanied with costly design iterations and many prototypes that slowly lead to an increase in experience. This lab course is intended to give an insight into the underlying effects by directly carrying out experiments. By investigating the function of a badly designed circuit in the lab a feeling for common mistakes and measurement methods to point them out is given. There is the possibility to modify the circuits and to improve their performance directly. Different examples for good solutions are shown and finally every attendant has the chance to develop an own design that will be checked by the course instructors for electromagnetic quality. Examples from daily business are also welcome.