Abstract: A coin discriminator system having a massive body integrally incorporated into one of the side walls of a passage channel for coins and which projects slightly outwardly form the level of the side wall towards the passage channel. The rolling coin strikes the transducer to produce mechanical vibrations which are transformed into electrical vibrations by a transducer and an electronic device. The massive body has a curved or spherical surface in relation to the projecting section of the wall. The base of the passage channel through which the coins roll has a slant so that the coins rolling along the channel abut against the side wall of the channel in which the massive body has been positioned.