This paper deals with the size decreasing and the power decreasing of rotating-head. The head is the most important part of the developed data-transmission system and is installed on the rotating spindle. The size decreasing is achieved by three methods; the adoption of one-way data-transmission from the rotating head toward the stationary head, the realization of function of nine electric-IC-parts by a one-chip micro-controller and the adoption of digital-filtering process after data transmission accompanying no RC-hardware filter in the rotating head. As a result of the three methods, also the power consumption at the electric circuit in the rotating head is decreased to 40mW, and the coin-type battery system and the non-contact power supply system are developed. Characteristics and composition know-how of the electric-circuit including thermo-couple in the rotating head are experimentally analyzed in detail.