Abstract: In an electronic watch, a sensor of the closed type which consists of an upper circular cover (10), a shell (20), a rotary turning disk (30), clamped between the upper cover and shell, the shell having a socket (23) on one side, a reed switch (50) enclosed in the socket, the turning disk forming a concave through (31), a pair of magnets (40) located laterally in the concave trough, an axial shaft, the shell having a first central orifice (21), the axial shaft being held in the orifice, a plier (32) extending from the side of the turning disk, the upper cover having a pair of lugs, the shell having a pair of second orifices on each side of the central first orifice (21), the lugs penetrating the second orifices, an external axial wheel, the plier (32) engaging the axial wheel.