- Put on some music.
That’s it! Watch the lights go on an off in response to the high and low
frequencies in the music. You can adjust the sensitivity of the LEDs by
turning the potentiometers.
Here are the obvious things to check out if you’re having a problem:Check that all the batteries are fresh and tight in the battery pack and
that all face the right direction.If one or two LEDs aren’t working, replace them.
If two LEDs in series with each other aren’t functioning, you might have
reversed the long and short leads of the LEDs; if so, just replace that pair
of LEDs.You are playing Brahm’s Lullaby. Brahm’s Lullabywill not light up a single
LED. Switch to Snoop Doggy Dogg or Motörhead.Taking It Further...........................................................................................
By now, you’re probably jumping and jiving to this cool light show, playing
every CD you have to see what they do, and still, you want more? Here are a
few different ways to take this project further:Obviously, you can change from a musical staff and notes to any kind of
shape you might want to define with your LEDs. You can have two stars
or a sun and moon, for example.You can use a band pass filterto add more layers of frequency. For exam-
ple, between your high pass filter and low pass filter, you could add two
more band pass filters to hit intermediate frequencies and have four sets
of LEDs going off in response to music.
You could miniaturize your circuit so you can pin it on your shirt or take
it with you to parties. A few steps would help you to get a smaller cir-
cuit. First, you could use smaller LEDs. (This project uses T-1^3 ⁄ 4 LEDs,
but you could use T1 LEDs.) You could also use a different method of
building the circuit called a dead bug circuit.Imagine an IC turned on its
back with its little prongs sticking up on the air, and you get an idea of
what we mean. This method doesn’t involve a breadboard but makes
connection directly to the LED. Check out http://www.arrl.org(American
Radio Relay League online) for some ideas about using the dead bug
approach to building circuits.Chapter 5: Making Light Dance to the Music 113