Introduction: Sound Reactive Led

Picture of Sound Reactive Led
This instructable shows how to modify a pair of speakers to also pulse an LED (or multiple leds, you choice) to the beat.

Step 1: Parts

Picture of Parts

For this project you shouldn't even need to buy anything

You need:

A pair of speakers (or one, whatever you want)

1 bright led (I chose red because I think it worked the best, plus it's my only bright LEDs on hand)

wires for permanent installation, or alligator clips for demonstration.

Step 2: Open the Speaker

Picture of Open the Speaker

Open up the speaker. Usually all the screws come out except one, so you just pull the case apart and it'll pop out.

Step 3: Locate the Speaker

Picture of Locate the Speaker

see that big metal thing? That's a speaker. If any wires are coming off of it (like another speaker) that's easier to reach, then just use that. I think mine was hook up to a tweeter? I'm not an audio guy, so I'm not sure.

Step 4: Attach

Picture of Attach

attach either a wire or aligator clips to each connector. connect the other ends of the wire or aligator clip to your led. Even though it's an led, polarity doesn't matter for this application since it's ac. No resistor is needed either.

Step 5: Crank It

Picture of Crank It

turn you speakers up and play music until the led is reactive. It starts being reactive at about 25%, but then (for me) it was best at half as loud as the speakers can go.


autokhin010 (author)2012-02-24

thank you so much!

wazzup333 (author)2009-05-01

Does anyone know if this will work on my 5.1 surround sound as I'm concerned about the voltage on the main bass speaker.... On the back it says 240 volts (This will blow the LED right?) and 50hz even though i don't think hertz matter..

marselsipod (author)wazzup3332009-05-09

yes it will. a regular led will need 3V, 3.5V max, and the absolute maximum commertial LED that i have seen was 24V

wkuace (author)marselsipod2009-06-12

wazzup333 do you have a meter? even a main bass speaker probably isn't getting 240v. the circuit driving the system probably just runs on 240. if you can find out what the speaker gets and then combine several led's in series it should work. for example if the speaker gets 12v then 4x 3v leds in series should work. I've never connected to speakers before so i'm not sure. also it seems like a speaker would be more of a current driven device then a voltage driven one. meaning it may step-down the 240v to a low voltage high current system. if that is the case be very careful be cause high amps can kill!!! to everyone who wants to try to contradict me. Yes its the amps that kill not voltage. people often build up tens of thousands of volts walking on carpet. but that is only pico-amps worth of charge. even 1.5v like in a AA battery can kill with enough current. it only takes about 50-60 mA across the heart to kill a person.

froggyman (author)wkuace2010-09-03

Technically its a combination of the both volts and amps... .5 amps at 1.5volts isn't going to do you any harm, but that same .5 amps at say 10,000volts will kill you quite easily and quickly assuming it is able to be ran through your heart.

wkuace (author)froggyman2010-09-06

Voltage makes it easier for the current to travel through the body, at 1.5 volts it would be impossible for 5 amps to kill you, it would probably take 1,000 or 10,000 amps at 1.5 volts to do the job but it could happen, though it is highly unlikely that you'll ever find 10,000 amps at 1.5 volts, you'll be most likely to find a high voltage low amp system

bobrigewitch (author)wkuace2011-11-21

Actually the voltage doesn't matter. 50mA (0.05A) across your heart will stop it from beating. Be it at 0.1V or 500,000V (although there's more fireworks at 500KV) it is possible to kill someone with a 1.5V battery, although not easy, it is possible.

wkuace (author)bobrigewitch2011-11-21

a 1.5v battery can't supply enough current to kill a person through their skin, or else it would happen all the time, (it may be possible if you insert electrodes into the veins and attach those to a AA battery it might be able to kill you). The problem is that the human body has an extremely high resistance (usually 500Kohm) Ohms law states V=IR or I =V/R at so 1.5/500K =0.000003 amps that can pass through your body from a 1.5v battery. Its way to small to kill you or even cause a slight tingling sensation which you start to feel at 0.001A

bobrigewitch (author)wkuace2011-11-22

With electrodes yes. I never said it was easy to, just possible.

hoihoi151 (author)2009-01-03

B very careful. if u have a post amp from ur music player 2 ur speaker this is very bad. if u r outputting more than 5volts 2 ur speaker then u can blowup the led. just putting in a caution

i like things that go BOOM!

LED's don't boom, they burn out, like light bulbs, but I like them too

bkjkhker (author)Ben The Builder2010-09-05

Actually, the day before yesterday me and my friend were hooking up some LED's and accidentally sent a straight 9v current through a 3v LED and after about 2 seconds it popped completely in half and launched across the room. It was pretty sweet haha :P

nodoubtman (author)bkjkhker2011-09-14

thats why you need a resistor :o)

Ben The Builder (author)bkjkhker2010-09-06

It must have been High Current, just a nine volt battery will semi melt the inside, rendering it useless, if it was a higher current battery like a large lead acid battery, it'll blow up anything you connect it to

superrust (author)hoihoi1512011-08-15

sorry i'm new to electronics. could this danger be avoided by adding a resistor to the led?

froggyman (author)2010-09-03

Hooking the LEDs up to the speaker directly shortens their life by a considerable amount because that sound current coming from the amp circuit/to the speakers is in AC. LEDs don't like AC current and it shortens their life. Instead you want to build a simple bridge rectifier out of 4 diodes (or you can buy a small pre-made one) to turn the current into DC so the LEDs will be happy and last longer. They aren't very hard to make. Wikipedia does a good job of explaining it and showing a simple schematic of the Diodes.

marc00703 (author)2010-06-06

I tried hooking up an LED to my speaker, but it wouldn't turn on until the volume was at it's maximum... I'de like to know how I can make this mod work without having to put the volume at it's maximum because it's WAY too loud :D

Chowmix12 (author)marc007032010-06-06

Be careful, but try and remove the resistor or lower the resistance...

Goalie1 (author)2010-05-11

Perfect instructable!! It works awesome for me!!

szechuan53 (author)2008-06-13

awesome, but can you make an LED ball or something and post it? (thats a dare)

Goalie1 (author)szechuan532010-05-09

Can that LED be a 5mm?

pescados666 (author)2009-08-13

Would it be possible to use a microphone connected to a preamp with the output from the preamp going to LED lights? Also, you might get better results if you didn't connect the LED to the tweeter because it is connected to a filter (the little capacitor) that only lets it receive high pitched sounds. It would be better to connect it in the wire before the midrange speaker and connect it to an inductor on the positive line so that it only lights when the bass hits. You would have to tune it with different sizes of inductors, and there's different levels for the filters that involve using a capacitor on it, but shouldn't be needed just for a light.

ScubaSteve (author)2009-07-30

Also, would this be any diffrent for a home stereo unit? i have a zenith ZA575M 47 Watt stereo system.

ScubaSteve (author)2009-07-30

how exactly would i make the LEDs more sensitive/responsive?

marselsipod (author)2009-07-02

i already tried to do this on two different pairs of speakers, still doesnt work. >.< please help

david422 (author)2009-06-30

This is how we do it in Sweden!!!! ;) Great instructable many thx!!

david422 (author)2009-06-30
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david422 (author)2009-06-30

Nice Instructable. But will this work with a LEDdimmer??

planelover93 (author)2009-06-21

I did this way before his tutorial, and it was a bit more complicated. It used an audio receiver, and a bulb i bought from Home Depot. I Put it in an emergency light casing.

I applied the concept on a smaller scale onto my Subwoofer

Then My Monitor...

Ive now got it on my Custom Computer too, but i bought the Cathodes.

But now im working on a bigger project, my whole Rooms ceiling line is going to have BLUE LEDs connected to a 2 Channel sound sensitive outlet. So my whole room will now beat to the sound of my 5.1 system! Im getting a new house, so i wont be seriously "modding" my room. But when i move into my new home. I plan for Sound sensitive LED backlit Translucent ceiling.

npa4863 (author)2009-06-04

I did the same instructable but i used some portable ipod speakers... i also used 2 red 12v leds for mine, in parallel with led holders and mounted it in the casing so no lose wires... i like my set cuz I'm drawing so much power that the power led goes slightly dim when i crank it its funny.... so any way i'm going to post a link to this instructable in case i happen to pick up any on looking to do up some PC speakers and maybe you could put up a link to mine for any one wishing to do ipod speak's, if you want...

thefonz13 (author)2009-05-27

could you do this with a black light?

unibomb bk (author)2009-04-12

freak'n awesome that solved alot of problem! way too freak'n cool

mattripsurfaceoff (author)2009-04-08

How would you add more leds but with the same hook up?

just put them in parallel

Jodex (author)mattripsurfaceoff2009-04-10

Just put (nearly) as many as you want to those alligator grips.. I think it woild work then

Ben The Builder (author)2009-04-03

One thing you guys could try, and I'm not 100% how it works, since I don't have one to test it with, but I think you put the output from a headphone jack (Headphones would work) and then you put however many volts your LED takes and if you hook it up right, the electricity from the speaker increases or decreases the voltage flowing from the + lead to the - lead thus proportionally varying the brightness of LED, there's an instructable on it somewhere

-Aj- (author)Ben The Builder2009-04-08

yeah that is the best way, it requires a transistor. you have a separate power supply for the led, then the signal from your audio controls the transistor and varies the power to the led proportionally. im sure there is an instructable lol

-Aj- (author)2009-04-08

if you have a lead that goes from headphone to rca it would be easy as you could just clip the leads straight onto the center pin and the outside. there are better ways to do this but for just making an led respond to sound you cant get much simpler.

instructables_user_4783 (author)2009-03-28

cool instructable but you need to turn up the volume on the speakers really loud for the LEDs to work. If you use this circuit and you have PC speakers with a built in volume control you can control the volume without turning off the LEDs. I have a video of it, the audio was relaid because my camera does not do a good job of recording audio.

geeklord (author)2009-03-04

it wouldn't hurt to put a small value resistor in line with the LED. 10 ohms maybe?

hoihoi151 (author)2009-01-03

in standard "crappy" speakers they use only a mid range spkr. if u had 2 spkrs in the one case the smaller is the tweet and the bigger is the mid. 3 spkrs and the big one is the low end, medium is middle and small is tweet. in the case of 4 the smallest is the Horn, but horns r very rare in desktop spkrs and r usually found only in stage shows. a megaphone is an example of a Horn.

bored_14 (author)2008-03-02

do u think any1 could make instructible on how to make alot of these and mayb hook them up to a guitar/bass amp? that would b sick alothough in the video it looks liek it only works the beats from the drums or w/e

viacin (author)bored_142008-08-23

It'll work with anything really, It's just hooked up to the bass speaker in this instructable (I'm assuming.) Try hooking it up to the larger speaker and see if it flashes. I'de suspect it would flash too much though.

GreenDay (author)viacin2008-12-02

The bass speaker would be the larger one, this is hooked up to the tweeter.

Davvik (author)bored_142008-09-23

The only reason it was working just for the drums or bass is because that is when it has the most current running through the wires and also the most jump in the speaker coil. So if you're playing 5th chords or just anything with a lot more volume it will make the LED work. But I'm not sure if you would need a resistor for like a 100Watt speaker or anything.

elvisjer (author)2008-11-22

Hey i love it and how simple it is. "Anyone can do this" is a great compliment, not something bad! I'm going to ad this in a positive way before someone trys to sound cool and smart and rude, but LEDs actually can induce distortion. I've built many guitar pedals and LOTS of lower line pedals, especially danelectro models use simple LEDs in the circuit to make them clip. Will it always add distortion, NOPE! But it can. For this project....if it sounds good....then rock on! Propz!

creech2009 (author)2008-11-11

Would it be possible to use head phones and just cut them off and connect to the LED?

Gamernotnerd (author)2008-11-03

On stronger it would make a nice metronome.

wolf555hound (author)2008-08-31

zomg(1337) I have to comment on the first and second song. for both, you're a genious, and have really good taste! ill post more when i actually read the ible...

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