How about a rhythmic light system that uses only one component? If you think this is impossible, it’s because you don’t know the “rhythmic” system yet. It is a system that uses a small rhythmic relay that is energized by the audio amplifier’s own output signal. The magnetization of the relay core attracts a blade closing the contact of an external circuit in which there is a lamp. The lamp will then accompany the opening and closing of the small relay to the rhythm of the music. The author of the project does not indicate the characteristics of the coil. 500 to 1 000 turns of enameled wire 28 AWG, or finer, requiring a power of at least 2 W. For its excitation, the shape for this coil as shown in the drawing can be a spool placed on a 4 cm thick screw in length and diameter between 3 and 5 mm. The blades are made of ferrous metal (steel, iron or brass) in order to be attracted by the magnetic field of the coil. for example, those obtained from relay contacts.
