Small high efficiency motors in order to produce large amounts of power must be operated such that they are running at high speed outside the desired vibration range for sexual stimulation. Accordingly, designs allowing for the appropriate gearing to allow heavy weights to be spun with small diameter and high efficiency whilst not increasing the outer diameter of an adult device are disclosed. Beneficial embodiments of the invention provide users with adult devices providing high impact (amplitude) vibration in a range of physical geometries compatible with providing internal and/or external stimulation which can also be offered at low cost and/or low manufacturing cost with extended operating life. Additionally, design flexibility via axial designs, non-axial designs, flexible drive designs, aperiodic drive designs, and linearly driven designs provide design solutions for implementing vibrators with low cost, high impact, targeted frequency characteristics, increased efficiency, and increased power.