Introduction: Sync LED to Music

This is a very basic circuit for syncing LED's to music.

There are several issues:

1. You do not need a 9volt power source, I have used 3volts and it worked

2. Depending on your speakers system setup you will have turn the volume up very loud
       - I have connected this to a Latte Ipearl mp3 player, the volume (0-32) had to be a 26    to  get the LED to start to blink.

3. Make a amplifier to correct problems with volume having to be very loud.

4. I could not get this work using headphones; it did not work because I could not get the enamel of the headphone wires, so I cut open the headphone jack and connected my own wires.

5. If you have an equalizer you can adjust the different frequencies to and the LED will blink accordingly.

Step 1: Connect and Enjoy.

Materials: (scavenge electronics if you can)

Power source - 3volts to 9volts should work
Resistor          -  220ohm, though I have used 150k and it worked
TIP31 NPN Transistor  (Negative Positive Negative)


1. Connect the resistor to the power and the positive side of the LED
2. Connect the negative (look for the flat side) of the LED to the center pin (collector) of the transistor
3. Connect the positive side of your audio signal to BASE on the transistor
4. Connect the negative side of your audio signal the Emitter of the transistor
5. Connect the negative side of your power source Emitter of the transistor
6. Turn on your power source, turn on you audio, turn up the volume and experiment with a equalizer (VLC player has one built in to the software and it is free)

Step 2: Placement of TIP31 NPN

you may use a bread board or simply soldier each step

Step 3: Be Positive

Connect positive pin of LED to center pin of transistor.

Step 4: 220ohm Resistor

connect one end of  resistor to negative pin of LED connect other end of resistor to power.

Step 5: You're Grounded

Connect emitter (E) pin to ground

*ground is the negative of your power source or battery

Step 6:

Connect base (B) pin of transistor to positive line in audio.

Step 7: You're Grounded Again

Negative from audio to ground on circuit

Step 8: And Again

Negative of battery/power source

Step 9: Something Positive

connect positive of battery/power source to circuit.

always good to connect power last so not as to fry anything.

Step 10: View From a Different Angle

Step 11: Enjoy

I made a few changes before making the video, in the video the blue wire is negative from audio and the white/blue wire is positive from video