Listening to music on my PC (proudly using WINAMP), I was wondering how it would be to have some LEDs blinking with the sound that came out from the P2 connector. So I decided to make a simple circuit to do that. It worked pretty well, so I decided to write a post with step-by-step instructions on how to do it. Hope you enjoy it!

Material and Equipment:

4 LEDs (any color)

P2 plug

2 position switch

TIP31 component

Box to put all the stuff (if you want)

Soldering iron and accessories

Cable

This project will work like this: you connect 4 LEDs in the +12V from your computer, they are soldered to a 2 position switch that will connect to a component called TIP31. This component gets the intensity transmitted by the P2 connector, and with that, makes the LEDs blink with the music.

You can follow this schematic (there are 3 different ones to help you understand it).







For this project, I decided to install everything inside a small black box I had here and made 6 holes in it. Four in the top for LEDs and one on each side for the switch and cables. You can follow the pictures:





With the box ready, it’s time to connect everything. I started with the LEDs, soldering one small cable connecting each one, so it would be easier to arrange them inside the box after.

After connecting all of the LEDs, you must connect the cable coming from the LEDs to the center pin of the switch. One side of the switch goes to the middle pin of the Tip31 component, and the other one goes to the ground cable.

Now it’s time to make the P2 connector. You can see that the P2 connector has 3 pins, they are, left channel, right channel and ground. So you have to decide if you want the left or right channel and then connect it with the left pin from the Tip31. Remember that if you connect the P2 using the left channel, only the right is enabled on the computer and this circuit won’t work. Usually the ground pin is the bigger one, and the others are small and similar. You have to connect the ground from P2 connector to the right pin of the Tip31 (right pin from Tip31 is ground)

On the other pin from the switch, you must connect it to the ground from Tip31. If the switch is closing the circuit with the Tip31, the LEDs will only blink if there is a signal coming from the P2 connector, and if it’s in the other direction, the LEDs will always be ON.

Now it’s time to put everything together in the box. As you can see in this picture, it’s not very organized, but after closing the box, it’ll look much better.

Job is done!!



I’ve recorded a video with my first test of the blinking LEDs. You can find it here.

Obs: In this video, I made it with just one LED to see if it would really work.

You can download the video of the final job HERE.

Here is the video of the finished project:

I don’t know if I was clear enought in this HowTo, I will re-check this in some time.

If you liked it, have any corrections or advice, please leave a comment!

Thanks for reading!