Abstract: A sensing device determines whether the ferromagnetic properties of a standard acceptable coin are matched by a coin under test. The two are compared in a sensing device which consists of a pair of substantially identical sensing coils wound around tube chutes so that each coin becomes the core of its associated coil. The sensing coils are, in turn, placed within the windings of a larger exciting coil used to induce voltages in the sensing coils. All the coils are rectangular in shape and the coins are forced to remain in an endwise relationship within the sensing coils so that their planes are parallel to the axes of their associated coils. The sensing coils are connected in a series opposed relationship so as to be "bucking" one another. Their combined output is fed into suitable circuitry for determining whether this output goes to zero or a voltage near zero within acceptable limits. If it does, then the coin is accepted as valid. If not, the coin is rejected as invalid.

Abstract: A flexible electromagnetic shield is provided. The shield comprises interlaced filaments of at least one glassy metal alloy. The glassy alloy has a maximum permeability of at least about 25,000 and a coercivity of less than about 0.08 Oe.