1 LM386 IC
1 TIP31 Transistor
1 3.5 mm auxiliary cable (I made my own for this
1 3.5 mm stereo jack (optional depending on how you want to build yours)
1 1K potentiometer (I used a trimmer)
1 10k potentiometer (I again used a trimmer because I control the volume from my phone)
1 470uF capacitor (I would have used a 220uF but did not have one)
1 22uF capacitor
1 .47uF capacitor
1 1.5 million ohm resistor
3 5mm LEDs (your choice in color)
And of course a power source (I recommend 8 AAs)
Step 2: The LEDs...
First We need to connect the ground from the 3.5mm cable or jack to the right pin on the TIP31 transistor.
Then connect either the right or left lead from the 3.5mm cable or jack to the left pin on the transistor.
Connect the negative power to the ground pin on the transistor.
The LEDs will be set up in series, so the long leg on the led will go into the same rail as the negative on another LED and so on.
Connect the middle pin of the transistor to the negative leg of the LED. And connect the positivd leg of the LED to your positive power source.
That's all that's needed to make the LEDs respond to music, now we need to be able to hear the music right? I'll show you how to do the LM386 next...
Step 3: The Audio Amp...
Next connect the positive power source to pin 6 and the negative power source to pin 4.
Now connect either the right or left (whichever you didnt connect to your transistor) from the 3.5 mm aux to pin 3.
I connect a 1.5 million ohm resistor from pin 3 to pin 8 to reduce the bass because my speaker has a terrible bass response.
The .47uF capacitor is not polarized and doesn't matter which way it goes in. Connect the capacitor from pin 8 to the negative power supply.
Connect the positive leg of the 470uF capacitor to pin 8 and the negative leg to the right pin of your 10k potentiometer and the middle pin to the postive lead of your speaker (This is your volume control). The negative lead of your speaker connects to your negative power supply.
If you have any questions feel free to ask, I've been having some trouble uploading this instructable so I hope it uploads ok... Be creative and happy prototyping! ;)