A tensioner for a traction drive to maintain a belt under tension includes a base part and a pivot arm connected to the base part for swinging about a rotation axis and having a free end for rotatable arrangement of a roller which is supported on the power transmitting member. The first to third rotation axes are provided for the main body, a hammer receiving portion is provided in an upper portion of the main body. The opposing electro-optical composite receptacle or electro-optical composite plug converts the electric signal to the optical signal and transmits to the optical fiber. The regulated power supply also includes a compensation signal generation circuit coupled to receive a switching signal representative of a switching of the switch in the switching power converter circuit.