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In a drilling operation fatique producing vibrational motion is produced in the drill string in the form of longitudinal and torsional load variations at the drill bit and throughout the bottom hole assembly. These load variations occur at least partially as a result of the irregularly shaped hole b

In a drilling operation fatique producing vibrational motion is produced in the drill string in the form of longitudinal and torsional load variations at the drill bit and throughout the bottom hole assembly. These load variations occur at least partially as a result of the irregularly shaped hole bottom which develops beneath the bit and which in turn cause the bit to rise and fall with rotation, and the bit loading to vary. In addition, the rotating drill string causes gyrations in the drill string which are transmitted to the bottom end of the drill string and drill bit in the form of load and torque variations. These variations in loading appear as longitudinal and torsional vibrations in the drill string. A dampening and shock absorbing mechanism is at least partially comprised of piezoelectric elements which are responsive to the vibrations of the drill string to produce electrical energy which is used to operate downhole electrical circuits.

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Apparatus for use in a drill string operating in a borehole, comprising: means for converting oscillating rotational and longitudinal motion occurring in said drill string into electrical energy; downhole electrically operated means; and means for transmitting said electrical energy to said downhole

Apparatus for use in a drill string operating in a borehole, comprising: means for converting oscillating rotational and longitudinal motion occurring in said drill string into electrical energy; downhole electrically operated means; and means for transmitting said electrical energy to said downhole electrically operated means.