This is my Magical Music Box which converts music into a light show. When i was daydreaming what to make for my final project, i wanted something that would make a light show for any song simply by hearing it.
8x 1k ohm resistors
5x 10k ohm
7x 560 ohm
3x 150 ohm
1x really really really big potentionmeter. so big its basically an on/off switch….
4x RGB LED’s
8x .1 uF capacitors
2x LM358N op amps
1x LM386 op amp
1x microphone sensor
2x 9v batteries with battery holders
approx 2 miles of wire
some kicking music to show off with
Real simply, i used a microphone circuit for input, amplified it, ran it threw a potentiometer so i could control how senstive it was to ambient noise then split it into 3 band pass filters to tune out other frequencies then used that as an input for my arduino. A simple conditional based on that input controlled 6 digital out pins with each pin connected to a single input on 2 separate red, green, blue LED’s. So since each LED has 3 inputs, thats 6 pins to control 4 RGB LED’s.
I ran everything off of 2 nine volt batteries, one as +9v and the other as -9v. Here is a simple power schematic to be used in conjunction with the schematic above. I used the arduino for all my grounds.
Now for the gritty details. I used the PDF titled Op Amps for Everyone, which i have included a copy of at the end of this post, to learn how to make a band pass filter. Specifically i used the Sallen Keys band pass filter located in section 18.104.22.168
For more detail: Nick Smith – Magical Music Box