Abstract: A coin handling apparatus contains a standard reference coin and a coin validation circuit that compares an inserted coin or slug with the reference coin as it passes through a chute toward a coin gate. The coin gate deflects the coin into a first path if the inserted coin is undersized and otherwise into a second path. The validation circuit produces a "valid coin" signal that indicates a match between the inserted coin and the reference coin, a "coin present" signal if any coin is being compared with the reference coin, and a photodetector output signal, all of which are applied as inputs to a surveillance circuit that analyzes those three signals and generates an output indicative of whether the inserted coin is being "strung", an output indicative of whether the inserted coin is a slug, and an "alert" signal that indicates whether either the coin is being strung or the inserted coin is a slug.

Abstract: An electronic coin verification mechanism includes first and second drive coils driven by complementary sinusoidal signals provided by an oscillator. First and second sense coils are disposed opposite the first and second drive coils and are inductively coupled thereto. A reference coin is removably retained between the first drive coil and first sense coil while a coin under test is guided along a predetermined path which passes between the second drive coil and second sense coil. A comparator coupled to the first and second sense coils compares the voltages inductively coupled thereto and generates an output signal when such inductively coupled voltages substantially equal one another for indicating that the coin under test matches the reference coin. The first and second drive coils and first and second sense coils are each planar and are advantageously provided by forming the same as spiral patterns of metal upon printed circuit boards.