shaft 13 b and is more preferably generally planar and includes a primary axis of rotation 14 b oriented substantially colinear with shaft 13 b and substantially perpendicular to the plane of platter 12 b switch 10 b is preferably positioned within platter 12 b but may also be attached externally thereto by any convenient means switch 10 b preferably extends generally radially outward from axis of rotation 14 b and more preferably does not intersect axis of rotation 14 b switch 20 b also includes a pair of spaced electrical contacts 28 b 29 b adapted to electrically connect the interior of distal portion 26 b to the exterior of switch 10 b switch 10 b further includes an electrically conducting fluid 30 b such as mercury or an aqueous electrolytic solution partially filling enclosure 20 b fluid 30 b preferably rests in proximal portion 22 b of switch 10 b when platter 12 b is at rest switch 10 b is preferably oriented such that distal portion 26 b is positioned generally radially outward from proximal portion 22 b relative to axis of rotation 14 b more preferentially switch 10 b is also oriented such that proximal portion 22 b is positioned below distal portion 26 b such that while platter 12 b is at rest gravity acts to retain fluid 30 b in proximal portion 22 b fig6 b illustrates the effects of rotation of platter 12 b on switch 10 b rotation of platter 12 b generates a radially outwardly acting force represented by arrow 36 b urging fluid 30 b into distal portion 26 b and into contact with the spaced electrical contacts 28 b and 29 b force 36 b is proportional to the rate of rotation of platter 12 b.