Watch the video to see the device in action!
Step 1: Supplies
1 Arduino Uno
1 5v power source to power the Arduino (I powered it through USB from my laptop)
1 Electret microphone
1 Green 10 LED bar graph (individual LEDs will work too)
1 Red 10 LED bar graph (individual LEDs will work too)
1 Orange LED (or any other color)
1 NPN Transistor 2N3904 or similar
2 0.1uF capacitor
1 100k ohm resistor
2 10k ohm resistor
13 220 ohm resistor (Or whatever will run your LEDs at 5v)
1 CD player
2 Big ol' speakers
I ran out of outputs with the Arduino Uno so my volume meter only uses 2 of the red bars. An Arduino Mega would provide more outputs and make a better volume meter.