Abstract: The invention relates to an arrangement for implementing a planar magnetic circuit on a circuit board. The arrangement includes (a) printed circuit board (PCB), wherein a conductive wire pattern of an inductive circuit is formed as well as openings through the circuit board close to the conductive pattern, (b) two ferrite pieces, at least one of which can be fitted into the openings so that the pieces may be pressed against one another from opposite sides of the circuit board, and (c) a mechanical clamp which can be fitted around the ferrite pieces to lock them to each other, whereby the clamp extends around the ferrite pieces located on both sides of the circuit board.