24 March 2017
BUILD IT YOURSELF
I've always had a fascination with
flashing lights — especially when
the lights are synchronized to
music. Long-time readers of Nuts &
Volts probably realized this about
me a while ago. Because of this
fascination, I have built more
varieties of color organs than I
should probably admit. If you are
unfamiliar with the term, a color
organ — also called a light organ —
is defined by Wikipedia as:
A circuit that separates the audio
signal into frequency bands and
controls the light channels
according to the average level of
each band. A typical party light
organ of the 1970s had three
spotlights — red, green, and blue —
for sounds in bass, medium
frequency, and high frequency.
By Craig A. Lindley
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Due to their simple design, analog color organs have been popular as DIY projects for electronics hobbyists for years, and can still be found for sale as kits on the Internet today.
(This proves I’m not the only one fascinated with flashing lights).
Unfortunately, most analog color organs don’t work very well, and
all of the colors end up flashing nearly all of the time regardless of
the music being listened to. What I was after when I designed this
color organ was to have good frequency selectivity so that the
color and brightness of the display LEDs are directly related to the
frequency content of the music; not just to its amplitude.
If one were to pull out the January 2008 issue of Nuts & Volts,
you would find an article I wrote about the design of the first
digital color organ I ever developed which used digital signal
processing (DSP) technology in place of traditional analog filtering.
I still get emails from people asking me if the design I presented in
that article has been updated because they are still interested in
Well, I have good news for those folks. In this article, I will
present an all new design for a color organ with features
unavailable in any other version I am aware of. Briefly, this new
1. Uses a string of 120 WS2812B RGB LEDs (also called
NeoPixels) for the lighting element.
2. Has a touchscreen LCD display which is used to configure
the color organ’s operation.
3. Has a built-in automatic volume control which allows the
color organ to respond correctly given changes in volume of the
input musical material.