Light organ

In the 1970s, light organs were a popular lighting effect used in discotheques and dance parties; and also during that period, the home entertainment manufacturer Morse-Electrophonic produced some of their stereo systems with a built-in light organ display (such as their "Stereo Bar").

The circuit of a light organ separates the audio signal into frequency bands and controls the light channels according to the average level of each band using dimmers.

Due to their simple structure, light organs were popular as DIY projects for electronics hobbyists in the 1970s and can still be found for sale on the internet.

In 1971, the Rickenbacker guitar company offered their 331LS "Lightshow" model (and matching bass, model 4005LS), the body of which contained a three-channel light organ (with a dimmer); each channel corresponded to the pitch of the strings being played.

The soundboard on these models was replaced with thin Plexiglas cutouts over a translucent moire diffraction material.