The construction of a silent continuous sweep motion quartz clock is almost exactly the same as a regular "ticking" quartz clock. The only difference is in the frequency of Voltage supplied to the coil of the Lavet motor and the corresponding mechanical gear ratio. The seconds hand in the silent clock makes 16 little steps per second instead of a single tick per second, which is much more quiet and creates the impression of a continuous movement of the seconds hand. The coil of the silent sweep Lavet motor receives square wave AC Voltage at 8 Hertz instead of 0.5 Hz in the regular ticking quartz clock.
This seems a good idea for a silent running clock, however a typical alkaline AA battery normally expected to run a quartz clock for at least 12 months will die in about 3 to 4 months in a silent sweep clock. The reason is that the Lavet motor consumes more power as it makes 16 steps per each second instead of a single step. To compensate for the greater power consumption some manufacturers, like Seiko or Rhythm, use C or D size battery in their silent clocks.