bill and comparing it to a maximum thickness value the thickness is measured by two fingers 80 82 fig4 that are mounted on opposite ends of a rotating shaft 84 and are spring biased against surface ridges 83 85 by a spring 86 on shaft 84 as the bill is grabbed at the nip points between the fingers and the ridges the nip points are spaced above the curved surface 48 and pulled along the surface 48 the bill forces the fingers upward by a distance equal to the thickness of the bill as the fingers are pushed upward they cause a corresponding rotation of the shaft 84 the rotation causes a pair of metal paddles 89 fig1 only one paddle is shown the other being the same shape as parallel to and mounted in the same orientation on the other side of board 94 as paddle 89 the paddles are mounted perpendicularly on the shaft to rotate with respect to stationary metal elements 87 only one shown that are formed on the surfaces of a circuit board 94 fig4 which is fixed in an orientation perpendicular to the shaft the stationary elements on the board form primary and secondary inductance coils and the paddles provide a field path linking the coils the metal paddles are electromagnetically coupled to the stationary elements so that the amount of rotation of the shaft 84 can be precisely detected by circuitry 96 mounted on the circuit board a circuit board of this kind known generally as a rotary variable inductance transducer rvit is available from trw electronics of hampton va the circuitry includes an analog to digital a d converter which receives an analog voltage signal generated by the rotation of the paddles relative to the stationary elements the algorithm for determining.