Abstract: A method or apparatus for facilitating the construction of prototype electronic circuits using printed circuit boards, by providing a printed circuit board 1, with a plurality of through connection bores 15 arranged in rows and columns, and with a conductive pad 4 at each end of each hole. A group of parallel conductive tracks 3 is provided on one face of the board substrate, the tracks 3 extending through the columns of pads 4, and a second group of conductive tracks 12 is provided on the other face of the board substrate, the tracks 12 being perpendicular to the tracks 3. The tracks 3 and 12 are connected to selected ones of the pads 4. In addition, conductive planes 5,9 are provided between the said first and second faces of the substrate, these planes being connected with selected ones of the plated through connections 15. Certain of the connections 15 are used for the purposes of mounting the connector pins of components.