Coin selector system which has a coin rolling track arranged to define a rolling path for a coin between: an entrance to the rolling track through which an inserted coin starts a path along the rolling track; and an end of the rolling track through which a coin exits the rolling path once it has travelled along said rolling path; the system comprising: - a light signal emitter element, arranged to emit a light signal incident on an edge of the coin and generate a reflected light signal; - a light signal receiver element, arranged to receive a light signal reflected by the edge of the coin; - means to process the filtered reflected signal to obtain a plurality of parameters from said signal and compare said parameters with corresponding parameters established for valid coins to determine if the coin is valid; wherein the emitter element and the receiver element are located on a line which is substantially parallel to the rolling track at a minimum distance from the rolling track bigger than the diameter of the coin with the biggest admissible size; characterized in that the emitter and the receiver are located and arranged and have a radiation diagram so that: - the distance between the emitter and the receiver is bigger than the diameter of the smallest admissible coin; - the axes of maximum radiation of the emitter and of maximum sensitivity of the receiver are perpendicular to the rolling track, such that there is no significant direct coupling between the emitter and the receiver if there is no coin in the area of analysis, the area of analysis of the coin edge being equivalent, at least, to the distance between the emitter and the receiver; - the emitter and the receiver have a radiation diagram approximate to the cosine law such that a quite planar output for the coupling between the emitter and receiver, due to the light signal reflected by the coin edge, is obtained during the entire path of the area of analysis. an entrance to the rolling track through which an inserted coin starts a path along the rolling track; and an end of the rolling track through which a coin exits the rolling path once it has travelled along said rolling path; - a light signal emitter element, arranged to emit a light signal incident on an edge of the coin and generate a reflected light signal; - a light signal receiver element, arranged to receive a light signal reflected by the edge of the coin; - means to process the filtered reflected signal to obtain a plurality of parameters from said signal and compare said parameters with corresponding parameters established for valid coins to determine if the coin is valid; - the distance between the emitter and the receiver is bigger than the diameter of the smallest admissible coin; - the axes of maximum radiation of the emitter and of maximum sensitivity of the receiver are perpendicular to the rolling track, such that there is no significant direct coupling between the emitter and the receiver if there is no coin in the area of analysis, the area of analysis of the coin edge being equivalent, at least, to the distance between the emitter and the receiver; - the emitter and the receiver have a radiation diagram approximate to the cosine law such that a quite planar output for the coupling between the emitter and receiver, due to the light signal reflected by the coin edge, is obtained during the entire path of the area of analysis.