OK, so the intro was a little over the top.
I'm not a big fan of bling, but I adore shiny lights. This instructable will tell you how to build an egg-shaped sound-reactive mood light thingy, with all the glitz and glamour of a real Faberge egg. It also has plenty of tiny fiddly painstaking work, also like a real Faberge egg.
What does it do? Quite simply, it's a 48-LED chaser circuit attached to a microphone. When it hears a loud noise (like a clap), a pulse is sent through the chaser circuit. All the while, changing colours illuminate the egg from the inside. This project requires absolutely no programming, but you will need elite ninja soldering skills. The Electric Ovaloid is made up of two basic circuits:
The LED Chaser
Take a look at the schematic for this one. It looks ridiculously easy, and it is! It's simply six inverters strung together in a chain, with an LED at each step. The trick is the resistor and capacitor at each stage. When the leading inverter changes state (high to low, low to high), it passes that along to the next inverter. However, that state is delayed by the need to charge up or discharge the capacitor. The charge time is determined by the RC time constant of the resistor (1.8 megohms) and the capacitor (0.1 uF) - about 0.18 seconds. If the initial state applied to that first inverter stays constant long enough, then the entire chain of LEDs will eventually turn all high or all low. However, by sending a pulse through the chain, we can cause a "wave" equivalent to the length of that pulse to travel through the chain of LEDs!
Note that the Electric Ovaloid uses eight groups of six inverters (each stage uses six inverters in a single 14-pin package) -- but yours can be of any length. Theoretically the chain could be hundreds of inverters long!
The Sound Pulser.
Do you remember The Clapper? That's basically what this is! When the microphone picks up a loud enough sound, it's amplified by the 741 op amp. It's then sent to the 555 timer which is configured as a "one-shot" timer. The inverter at the end formats the pulse for the chaser circuit. The sound, no matter how brief, is stretched out by the timer to a certain minimum value. In this case, it's the time needed to illuminate at least two LEDs in the chaser circuit. The number of illuminated LEDs (the period of the wave) is determined by the RC time constant of R8 and C4. The sound pulser schematic is a modified version of the one I found here
Want to make yours faster or slower? Just remember that the "speed" the wave travels through the LED chain is determined by the RC time constant - reduce the value of the resistor or the capacitor to increase the speed. The minimum number of illuminated LEDs (the period of the wave) is determined by the RC time constant of the Pulser circuit. Easy enough? Let's get building!