Abstract: Disclosed is a sensing device for monitoring the rotation of a shaft or other mechanical movements. A magnetic structure is positioned on the shaft for rotation therewith and provides a plurality of discrete magnetic poles about the shaft at uniform spaced apart locations. The magnetic structure is formed of flexible plastic, permanent magnet material cut in a castellated configuration to form a plurality of uniformly spaced apart magnetic pole elements.

Abstract: The embodiment of the invention disclosed herein is directed to a solid state seed sensor which includes a light-emitting diode for directing a quantity of light to a pair of photoresponsive transistors. The light-emitting diode and photoresponsive transistors are maintained within a housing structure wherein all electronic components are mounted, such housing structure being formed of two halves with interconnection between circuit portions being accomplished through sealed passages formed through the housing halves. The light-emitting diode and associated resistor are maintained in one housing half while the remaining electronic circuitry, including the photoresponsive transistors, are maintained in the other housing half.