A reversed cube air filter assembly has a frame and filter media. The lower cap has a shaft to couple with a spiral spring coupled with a rotary barrel on the outer side by fastening to a tail end of it. In the seal ring region 106, there is formed a pn junction acting as a nonconducting part 104, which blocks conduction in a path from the logic unit, through the seal ring 105 to the analog unit 153. An associated method combines the functions of marking ball location and receiving golfing instruction, using the novel apparatus.