This Instructable will show you how to make a LED Controller that can be directly wired to a car sub woofer amplifier or standard speaker output. It is constructed entirely of recycled parts and may cost you nothing.
I chose to make this Instructable as I was unable to find a device similar to this available for purchase
A Video of it in action is attached as it takes too long to convert. You probably need Quicktime or VLC.
The controller uses a 12V SLA battery and a transistor to control when the lights should be active by monitoring the speaker output. It works best when wired to a subwoofer as it only activates the lights when a beat is present.
You will need:
A box to put it in (I used an old Pioneer home theater speaker)
A Heavy Duty Transistor( The transistor I used was a ST W14NC50 from an old Compaq power supply unit)
A soldering iron
A switch (optional)
3 Speaker input ports(don't know what their actually called)
A 12 Battery. (Make sure the voltage isn't to high over 12V as you may blow the LED's)