A circuit board comprising an insulating substrate, via-holes made in the insulating substrate, and a wiring conductor having at least one layer disposed on the insulating substrate. The fuel injector comprises a valve group subassembly and a coil group subassembly. Each actuator is electrically connected to an amplifier unit. A resilient member is coupled to the base portion of the metallic pin-lock and to a mobile phone housing. First and second gear trains transmit torque between the rotary input and each grinding mechanism, with a one-way clutch provided in each gear train and an auxiliary gear allows both grinding mechanisms to rotate in the same sense.