Long before the dawn of digital music, folks employed the power of the electric color organ (aka “light organ”) to add some synced visuals to their hi-fi experience. Schematics for building such a beast based on AC power and incandescent bulbs can be be found fairly easily on the web, but plans for comparable LED-based designs seem a bit harder to come by.
Adapted from Aaron Cake’s 3 Channel Spectrum Analyzer, I built my own analog LED Color Organ to enhance the aural experience. The circuit uses 4 operational amplifiers plus ultra-bright 5mm LEDs to respond visually for bass, mid, and treble frequencies. A parts bundle for building your own incarnation of the project is now available from Jameco.
Schematic updated 11/1/10, Larger size available here
In order to simplify the construction process, I drew up and printed a label specifying the pinout for quad op amp ICs. Those interested in printing their own can download the design here.
I’ll likely continue tweaking the design as I continue the unusually groovy process of testing this thing. I predict a second channel plus somewhat more dramatic display option may be in my future ;)