Blinking LEDs to Music

This is a fairly simple project for anyone with some electronic skills.
Plug this circuit into an audio source and the LEDs will blink to the rhythm of the music. All it is really is using the voltage from the audio input to activate a transistor and turn on the LEDs.
This is circuit is very customizable. The setup of the lights is really up to you. The main thing to consider when choosing layout for the LEDs is your audio source and the power supply you will be using.
For this particular one I choose to make it run off a 9v battery and use an IPod for input.

Step 1: What You Need

Depending on the configuration of you setup you may need to modify the number of parts below.
Parts:
Superbright LEDs, the number and color is up to you (I used 4 blue ones).
2 x TIP 31 NPN Transistor, the heart of the project.
Audio cord (a headphone cord will do or just an 1/8 inch jack)
case (I used a spare thick cardboard box)
9v battery clip (or the power supply you are using)

Tools:
Soldering iron
Wire cutters/Strippers

Comments

[SabrinaReedz]

could you post the full part number of the transistor please?

[jjmaia]

Hope you can help me.
I have done everythimng as you said and it wont work.
This is the result: http://youtu.be/9Ro8YOpZgzw

[solid nrg]

how would you get sound if your audio cord is going to your ipod and to the led blinking box were would the sound come when the audio cord is in the ipod it thinks that is connected to a audio device or somthing no sound thogh dont you need a Y cable audio splitter for it?

[kewiss]

ok so let's clear something up first... I'm a complete noob, i've never done any electrical circuits or anything...all i know about electricity is from my highschool basic physics course. PERIOD!

BUT.... i'm pretty positive i can do this... WHY?... coz i love my car

so, here's the deal: i want to apply this same idea to my car stereo but instead of:
1- leds - led strips (12V)
2- 9V battery - car battery (12V)

Will these transistors work? will the whole idea work?

when i tried to connect them directly to the speakers, no light at all but i didnt try at high volume (pure imagination: based on the voltage drop i notice at high volume, aka all car lights slightly blink to the beat at high volume, i think it might light up just a bit) will this system work even at relatively low volume? (about 70% of the volume)

and should i connect it to the amplifier or speakers? or doesn't matter?

thanks in advance

[bunso]

can it use any players? like chine mp4 or mp3?

[ARJOON]

can i add a pot at the gate of each transistor to adjust sensitivity?

[ARJOON]

better use LED strips and a 12V power supply

[alastairflindall]

Hey, I want to buy what you've made, I'm awful at making these things, no patience and I'm afraid that it wouldn't pass the PAT test at my university, and it needs to be finished for 3 weeks time. Is there any chance you know where I can get this or in fact buy yours?

[sin3kveer]

My plan
11 LED
32V DC power supply
so need of registor..
I had placed LEDs on a plastic stripe accurately.
Did i use Transistor. TIP31 for this circuit

[pete54321]

Hey guys. Great tutorial. I just bought a 5 meter strip off eBay with 300 LEDs in it. Would it be possible to hook that many up to this? If so what sort of stuff would I need? I plan to plug it into my receivers audio output, which is already hooked up with circuit breakers and resistors so I don't think that they'll be nessesseary.
Any help is appreciated!
Thanks everyone :)

[megadethfan3000]

I need to know, would such a circuit be functional (See picture below) Considering this is supposed to be 6 LEDs for left and 6 LEDs for right, would it actually work?

Thanks in advance for any helpful advice :)

[cowarrior]

hey what is that object which is joined with tip31 transistor?

[megadethfan3000]

the 9volt battery?

[cowarrior]

you must have used resistors for this experiment. The diagram above is not an ideal one..but it was a good try..

[megadethfan3000]

It does, tried it, works great...

[Anoopsingh50]

Hey i made this just like the guide said but my LEDs are flashing but they are very dim.

Please help, thanks.

[samalert]

my leds are also flashing so dim its jst ridiculous to see those of mine also my left and right set of leds blink the same is there a way i did wrong

[cowarrior]

i think its because of the low voltage battery/power supply/adapter/transformer...

[Scratch17]

Is there a way to alter this circuit to force a current through the LEDs to keep them at a dim light level, then they grow brighter as sound is introduced, instead of going from off to bright?

[bobdan]

One way to do it is put a bypass resistor across the collector and emitter. I ran a circuit simulation with a 2N2222A npn, two diodes in parallel(unlike his in series), and the two resistors. The R(emitter) was around 80 ohms and R(collector to ground) was about 500 ohms. It allows normal current flow while there is a signal on the base, and cuts the current way down when there would be no sound. There are better ways of doing but it would take redesigning.

[drobbins2]

Would be neat to use this with a mic and Musical Equipment

[redlizard5]

what about the ground cord from the headphone cord

[redlizard5]

can you use two diffeerent transistors

[tcarlson2]

The 7805 devices are +5V voltage regulators and cannot be used as a transistor. The tab is ground, one pin is an input (voltage greater than +5v) and the other will be a steady +5V output. Replace the 7805s with the proper transistors and it should work.

[tcarlson2]

Hot glue is okay unless you leave the box in a hot environment, like a car (car dash in particular). Then the glue will melt and parts will move. For hot environments, once everything is tested and working as desired, use epoxy to secure the LEDs, switch, etc. in the box.

[tcarlson2]

You have left/right reversed. A TSR connector usually has tip as the left channel, the middle as the right channel, and the bottom as ground. That is standard for the audio world.

[hsarode1]

Can we use any NPN Transistor.

[cjiménez4]

Ey thankyou, very good explanation.

[MichielB]

Hi, great instructable, wow! ;) I'm planning to make something simular.

I added a picture of a schematic, will this work like this?

1) Can I use the BD243B in order of the TIP31?

2) I want 2 series of leds in parallel. One serie for the left audio channel and one for the right. With the pot I want to regulate the reaction of the leds when I turn the volume up or down. Is the correct place for it like in the picture, or has there to be one in the "Audio left" and "Audio right" line?

3) I also want to add a switch, to turn the LED's on without the audio-option. Where do I have to place it then?

Thanks in advance, and sorry for my bad english ;) I'm from Belgium.

[Hola_Amigo]

Will it work if I use TIP 107 transistors? or only TIP 31? because mine isn't lighting up at all.

[JONN123]

if only use 2 leds what kind of battery shoulg i use

[Jedrokivich]

Where did you get those transistors? Did you order them online?

[rawuol]

so i tried to make the same thing. in my area no one stocks electronic components or at least none that Ive been able to track down. So I made the entire unit as described in the instructable. Soldier is tight. Connections solid. No shorts. All new components. My issue is when I turn the unit on, the lights come one and stay on, even when its not plugged into an audio jack. No blinking, just on. Nice and bright I may add.
So where may I have gone wrong?
I suspect 1 of 2 things...
1.The cable I used is ring/sleeve/tip, but came from a camcorder a\v cable. Thats a stereo 3.5mm to 2 rca jacks(yellow and black).
2. The transistors I used were the only ones on the shelves available. They are 3 pin voltage regulators: 7805 - +5VDC - 1A.
Aside from that I used 4 leds, a 9V, and a hobbie box.

Lemme know if you can help, thanks!

[pearhart]

I know it might be a little late, but i had the same problem. If anything connected to the circuit touches the back of the transistor it can do that.

hope it helps

[Beduk]

you require tip 31 transistors.You cannot use any other transistors.

[RoninVj]

you can use similar NPN transistors if you connect with the right leads.

[jayeshshinai]

HAHA my leds lighting up according to the music in ur video!! :D

[FatRider]

Hi. Love your post and I want to do a similar thing.

Exept I don't have a 9V power supply but 12V.
What type of resistor or something like that i need to use?

Sorry my english and I'm new with this ^^

[axeman911]

here's a link to one music leds in which it uses twelve volts-http://www.instructables.com/id/Music-LED-Light-Box/

[qwertz0]

volt / amper = Ohm
12=0.02 (20 mA/LED) =600 Ohm

600 Ohm MINIMUM!