DIY Music activated LED controller

i decided to make a instructable on this since i couldn't find one when i needed it. This is a very simple DIY project. first of all your going to need a TIP 31 transistor, 12V power source, breadboard, wire, and L.E.D's. you don't need the breadboard necessarily i made my own PCB for this project. I've also included a very easy and cheap method of PCB etching.

Step 1 Gather Your Parts!

1 TIP31 Transistor 
12 VDC Power source
Breadboard (optional)
Wire
L.E.Ds

If you are going to etch your PCB you're going to need some Ferric Chloride, all i could find was the etching solution they sell at Radioshack. PCB board, also purchased from Radioshack. A plastic container, latex gloves, and a sharpie Marker.

Comments

[rageous]

Those lights you have were bought from Toys r us..... I bought the same ones for my son.... They already have a built circuit to sync the L.E.D.'s with music and it also has a microphone built in to sync the L.E.D.'s with voice.

What did you build? I'll post pictures of the lights I have.

at least explain what your talking about!!!

[duggerpato]

This is all pretty vague, buddy.

So did you make the lights shown, and where is their power source coming from?

Other than the PCB etching comments, this doesn't really show how to do what you did, you know? It's your first one, so keep trying.

[Andale_The_Great]

Ok. This is really generic so I thought I'd ask what's goin on.
You have a power supply for the LEDs.
Your (+) input I would think is your headphone output. ???
The (-) is tied together with the LED power supply's (-). Ummm, is that safe?
The switch seems to just be there as an on/off.

So if I'm understanding this right you are using the headphones output to control the transistor which works as a switch/dimmer for the LED's power supply which can be as big as necessary for the amount of LEDs you're using.

Am I right? Does that really work? I'm a little worried about the negatives being tied together.