Don't know what a transistor is? Don't know how to code an Arduino? Don't worry! This instructable will show you how to tie LED fixtures to flash with the beat of your music. A few things to point out is that, based on this setup the lights will flash mostly to the bass line of the music. Is this the best way to go about flashing lights with music? No, it's relatively crude but it has lasted me a full year of use and only costed $40.

You will need:

-LED fixture from this link (and found at any autozone)
http://www.autozone.com/autozone/accessories/Type-S-4-pcs-blue-LED-undercar-kit/_/N-25ve?counter=0&itemIdentifier=204999_0_0_

-Wire strippers

-Electrical tape (or shrink wrap tubing)

-A bass speaker you want to have the lights react with

Step 1: Buy the LED's

Like I said they can be found at autozone and look like this:
http://www.autozone.com/autozone/accessories/Type-S-4-pcs-blue-LED-undercar-kit/_/N-25ve?counter=0&itemIdentifier=204999_0_0_

I haven't tried this with other LED's from autozone, but they should work because all of them are supposed to be regulated from a 12V DC source (aka a car battery)

Step 2: Attach LED's

Literally all you have to do is put the two wires coming out of the LED into the two speaker terminals on a speaker. Strip the plastic off of the wire with the wire strippers so you can twist it with the speaker wire. You'll notice that the LED illuminates with each music beat. The louder the song, the brighter the LED. I had said earlier that my setup had lasted me 1 year. This is because I played my music loud constantly in my car and this eventually burned out several LED fixtures.

NOTE: The Speaker terminal in the picture shows only the speaker wire, not the LED wire running to it

Step 3: Project Time

http://www.youtube.com/watch?v=0NPDyF5uI7Y&context=C3b09949ADOEgsToPDskL0mfMEZYUN4-c-YTsQZ-M6

These can be used with just about any bass speaker. Here are a couple project I've made with them.
Check out what they look like at a low volume:

(sorry about the quality)