Sync LEDs to Music




Introduction: Sync LEDs to Music


Here's a link to the wiring schematic that was removed

In this Instructable, I'll show you how to sync LEDs to music. I know this have been done before multiple times but this time I'll try to do it as clear and easy as possible. My camera is bad so please bare with me.

I've also made a video tutorial!

Step 1: What You Need

*This is what you need to make 1 channel. Double the quantity of this part if you want stereo.

9 volt battery
9 volt battery clip
*TIP31 (Or other NPN transistor)
*2 LEDs
*220 ohm resistor
audio cable or old headphones


If you have a breadboard you only need:
a knife or scissors
(optional) 3 alligator clips

If you want to make it permanent you'll need:
Soldering iron and solder
on/off switch
(optional) project enclosure

Step 2: Assembly

Everything will be done step for step in the pictures below as well.

1 Making it with a breadboard:

Start with connecting the 9v battery to the bus lane. Then put the TIP31 vertically somewhere near that bus lane.
Hook up the cathode (shorter lead) of the first LED to the collector (middle) pin of the transistor. Then connect the cathode of the secound LED to the anode of the first. The secound LED's cathode goes via 220 ohm resistor to positive voltage.
Connect the emitter of the TIP31 to ground on the bus lane.
Connect an alligator clip to a jumper wire and connect that jumper to the base of the transistor.
The other end of the alligator clip goes to left or right channel in the audio cable.
Connect another alligator clip to a jumper wire and hook it up to ground.
The other end goes to the power in the audio jack, there might be several power cables inside, any of them will do.
Copy everything if you want two channels.

2 Making it permanent (Both channels)

Solder both resistors to the positive end of the battery clip.
Solder 3 wires to the negative end of the battery clip.
Solder the anode (Longer lead) of one LED to the cathode of the other one.
Repeat above step.
Then solder the anode of the 2nd LEDs to the resistors
Solder two of the cables to ground to the emitter pins of the transistors.
The collector pins are soldered to the cathode of the two LEDs
The base pins are soldered to respectively the right and left channels in the audio cable.
The third cable to ground goes to the power cable in the audio cable.
If you want a switch solder the positive voltage to pin 1 on the switch and the
continiuing cable on the secound pin.

Step 3: And How Does It Look?

Well there is only one answer to that!



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    123 Discussions

    I did this project exactly
    I couldn't get anything from a phone or a mp 4 but got it with my audio mixer that sets out 20v
    After about 10 secs the wires at the battery started melting
    Is it because the mixer has too much power ?
    If so what do i do???????

    1 reply

    I have not tried this yet, but will be receiving my Bachelors in Electronic Engineering this weekend. From what I've gathered, you didn't "do this project exactly." If the wires melted, then YES, you have given too much power through the mixer, which probably has destroyed some (if not all) of the components used. The idea proposed is not the best way to produce the effect, but I have tested it virtually, and it does work with a .5V output (say from an MP3 player on max volume).

    im a newbie, i tried this circuit, and its doing fine, but when i use Y-splitter to hear the sound, LED became dim.. any suggention for a newbie.. thanks help help help

    can i use 12v 5amps battery to make this project with 4 leds (3v) and TIP 31c transistor.


    Please reply fast.

    Hi Guys, Can anyone help me with this little project. I made this work on 3.5 audio jack but I wanted to replace audio source to mic. Is this possible? can anyone send me a working photo/video of this schematics ( Please be advised that I have no electronic background. I learn from what I saw on youtube :D cheers. TIA


    hi made this circuit like this project i used 4 led but the circuit doesnt work like stereo...can u help me about that?

    Hello guys i want to make my 12v led strip flash to music so if you could please confirm if it would work i would make and test it but i have ordered the parts which will take 2-3 weeks to come and i don't want to waste any parts i also want it to be stereo
    here is the diagram

    Nobody cares. And I suspect that wasn't the very first time someone made sound reactive lights. Again, nobody but you should care.

    Video of my Working Prototypes! i maked 4 DIFFERENT WAYS!

    How strong an amp did you hook this up to? I built this circuit earlier today and at first it would not work. I double checked it, and it seemed the circuit itself was fine. It turns out it did not work because I had it hooked up to my headphone plug. The power from it is just not strong enough. I hooked it to an amp torn out of old crappy speakers and it worked OK. It would only work on high volume, and even then the response was not that great. Nowhere near your video, certainly. I'm wondering what your amp is so I can get an idea of how strong it needs to be to get good performance.

    8 replies

    For me it works even with an iPod. I use simply an audio output on my pc in the video. I do not describe properly how you solder audio cables in this instructable. (Not taking the colored stuff off will block all weak signals that is trying to pass through I think)

    Hmm.... I just used gator clips to connect the circuit as in your diagram. I re-did it today to double check and got the same results as before. I just realized I got a TIP31C, and you used a TIP31. I'll try to get a TIP31 tomorrow and see if it makes a difference.

    I have tried it with TIP31C too and it works just the same for me. Are you sure your battery is fully charged?? (The circuit works with almost all NPN transistors!)

    1. can i hook up a whole strand of about15 leds to this?
    2. or do i have to wire them in parallel?
    3. i am using a computer power supply.

    As long as you have enough voltage you can attach as many LEDs as you wish to this, however there are some things you should take into consideration:
    Depending on the voltage the transistor(s) might get hot, look into using a heatsink if this is the case. Make sure the mA wont fry the LEDs, make sure to use proper resistors for your circut. You wire them in series, as I do in the instructable but with more than two LEDs. (Per channel if you're planning on a stereo setup)

    I'm using BC547 and it is also a NPN transistor.. My input would be 4.8v. But it's glowing very dim. I've tested with my Sony Walkman and Laptop, i get the same problem. I've tried out with White LED

    This instructable could clearly be a lot better, as many seem to be having the same problems. However, your problem MIGHT be your power supply, remember that volt isn't the only factor in making this work, you have to have proper mA (Milli amperes) and also direct current. (DC as opposed to Alternating Current/AC).
    Does it blink faintly in rhythm, or just glow faintly? If the latter is the case you might have a short or an improper grounding.

    I would go for "Blink faintly in Rhythm" . In simple words it's overall performance is low.. I barely see the difference during morning times.. Should i amplify it? Will it damage the LEDs? Rite now i'm using 4 RED and 4 BLUE LEDs connected in parallel with two 220k resistors from Batt +