A simple planetary or epicyclic gear mechanism consists of a sun gear in the center, an internal or ring gear with a common axis with sun gear, and at least one planet gear. The planet gear is located between the sun gear and ring gear, and meshes with both the sun gear and the ring gear. If the ring gear is stationary, when sun gear rotates, the planet gear not only rotates about its axis, its axis also rotate around the axis of sun gear. In stead of employing the sliding motion between the ring and the brush in electrical slip ring, the current invention makes use of a plurality of conductive gears, particularly a planetary gear mechanism, to transfer electrical power, and/or signal(s) between relatively rotatable objects.