My next door neighbors have recently been playing their music really loud so that I can hear it through the walls. I’ve gotten tired of having to bang on the walls each time to get them to quiet down, so I decided to automate some payback. The premise is that my device will listen for loud music playing through the wall, and when the volume breaks a pre-defined threshold and hears sustained music for 10 seconds it will start playing a CD player with annoying music and blast it back at them. After playing for a certain period of time it will pause the music and go back into monitoring mode. If the neighbors are still loud it will blast the music again and again indefinitely.
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.
Step 2: Setting Up the Circuit
You can download the Fritzing file of the circuit I set up.