In this Instructable I will be showing you how to create a light reactive LED system. In this clip, I used a single color LED strip, but you you can use a single LED, multiple LEDs wired together, single color or RGB LED strip, it just depends on what you are trying to build. The set up is fairly simple, the component list is fairly basic so if you are a tinkerer you should already have the majority of the materials laying around. If not, I will post links to the components I used so you can order parts and get to work! 

In the following link you will see the entire setup. Obviously you may arrange it anyway you would like, I just kept everything close and compact for the sake of an easy video. 


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Step 1: Components

Picture of Components
For this project you will need the following:

1) LED  ~$20 (with shipping) 
- For this project I used a solid blue LED strip which I purchased on amazon. These 5 meter SMD 5050 strips can run around $70 in retail stores so I though I would be taking a chance purchasing something priced under $20, but I was not disappointed in the least. I'm sure there are better quality lights out there, but if you plan on cutting these up and have no real game plan you wont feel any guilt putting these through the ringer.

2) Mini breadboard  $5

3) Arduino Uno  $30

4) Solid core wire  $2.50
- For anything involving breadboarding, do yourself a favor and stay away from any stranded wire. It will just end up getting frayed and hard to manage. Solid core is the way to go. I also like to choose at least two different colors for my wire to keep grounds and powers visibly separate. It makes troubleshooting and wiring easier in the long run when dealing with a lot of components.

5) USB A to B cable  $4
- This will be used to upload your Arduino LED code to the Arduino Uno board

6) Wire cutter/stripper $5
7) Parallax Sound Impact Sensor $10

8) Wall Adapter Power Supply - 9VDC 650mA $6

Total cost will be a bout $80 but keep in mind, all of these components are completely reusable. You can recycle them into a multitude of projects in the future so try not to worry about the cost. Think of it as building up your technical tool box :)
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Dashie Pony20 days ago
Hi I cant seem to get the arduino code to work with my uno r3. When compiling it comes up with various errors such as led strip was not declared in this scope and invalid preprocessing directive #DEFINE and in function 'void setup () '. Please reply as this looks likable an awesome project!
tdang1121 days ago
Say I wanted to use this set of RGB LED strip

How would I set everything up?
JasonG31 month ago

Hi, I really like your project and I've built it, but I need so help with contextualizing. I am doing this for a class project, and I wanted to just add a PIR motion sensor as an on and off switch for the reactive leds. Would appreciate any help.

ro8erts57 months ago

So I'm really new to electronics and I am attempting to do this with 1m tricolor LEDs from RadioShack. However my LEDs have 3 leads at the end to plug into my Arduino's ports. Also I can't see any noticeable reaction from my sensor, even when I replaced the strip with a single LED in the breadboard as was shown in the picture of the circuit. Any suggestions as to what might be going on?

cobdor7 ro8erts53 months ago

Try connecting your sensor to analog instead of digital. Then replace the word digital in the code, with analog. Make sure to change your setup accordingly as well. As for the tri color lights you will notice that they wont listen to the sensor. This can be solved by putting a 0 in void send_1M_pattern(const unsigned long data[0][10], int pattern_no, int frame_rate).

coolmuggy3 months ago

Ok, I made this project and I got it to work only with USB power.. if i plug in my DC power the project doesn't work (light stays on all the time - blinks very little with the sound). something wrong with my Arduino?

oxSiMoNxo3 months ago

i am having some troubles the sound sensor is not picking up anything and i was wondering if it has anything to do with the sensor, it´s the following

noah.stahl3 months ago

Is there anyway to program it to only pick up bass frequencies? From 10Hz to 300Hz?

JohnnyRoelofs3 months ago

From the video, it looks like it's programmed so that the LED is always on, and then during big bass moments it cuts the light off. Is there a way to program it so that it can be the other way around (the LED only illuminates during the bass hits)? This is my first arduino project- thank you for the inspiration!

GraziCNU (author)  JohnnyRoelofs3 months ago

Thanks for the feedback man! To get the behavior you are looking for, just swap the following instances in the code:

analogWrite(LEDstrip, 255);

analogWrite(LEDstrip, 0);

255 is the highest pwm value (essentially just a binary "on" at this point) and in my example I set that as the starting state. 0 is a binary "off" which I set as the behavior for when the impact sensor sends out a signal. Just make the initial state 0 and the trigger state to be 255. Let me know if you have any questions!

Awesome- thanks so much!

dallas20004 months ago

Does this project use the breadboard at all? It's not included in the schematic.

GraziCNU (author)  dallas20004 months ago

It does, I just made an assumption people knew how to wire the breadboard with my description. I can make another schematic with the intermediate bread board connections though!

I understand how the breadboard works, and I'm assuming that the arduino's ground and vin connect to the breadboard, and the LED connects to the breadboard as well, taking the arduino's vin. Is this correct?

GraziCNU (author)  dallas20004 months ago

You got it :)

jkalna229 months ago

very misleading. You show a rgb led strip in your main picture but then fail to explain how to set it up. You explained the concept well though.

GraziCNU (author)  jkalna224 months ago

Actually, I only own a single led strip haha (the single blue strip that was pictured throughout this tutorial). Am I missing something?

Anth0ny9 months ago

How can you let the led strip work because when i made it the led's doesn't work. The scematic is for 1 led and not for a led strip who needs 12 volt. Can somebody help me with this problem ??

GraziCNU (author)  Anth0ny4 months ago

The LED Strip should have LEDs internally wired in parallel. I just used the single led to minimize clutter. The connections with the strip should be the same, one power one ground. The LEDs will be dimmer with the 9V supply I used, but they are rated for 12V. Does this clear anything up?

Raitis Anth0ny9 months ago

There are plenty of tutorials and probably instructables that describe hooking up led strips to Arduino. Simply put: use a transistor as a switch for the LED strip.

i need that kind of answer also :S

nr0025419 months ago


I am having problems. When i connect the led ground to the output of the sensor this works fine but when the arduino is connected the leds just stay on. Do you reckon i have a dodgy arduino or is there something wrong in the code others have had issues with?

GraziCNU (author)  nr0025414 months ago

Would you be able to tell me what GPIO pin are you plugging it into?

theViTALiTY9 months ago

Wait i dont get it, how does the LED strip get enough power since its 12V, and we are powering arduino with only 9V. Can this thing be done without arduino, just a plain connection from parallax to led strip?

GraziCNU (author)  theViTALiTY4 months ago

It is just dimmer with 9V as opposed to 12V. It can be done without an Arduino if you wish.

rharrison29 months ago

How many LED strips can you control with one sounds impact sensor?

GraziCNU (author)  rharrison24 months ago

As many as PWM pins you have access to.

schwaigor7 months ago

Great post man. I am no way educated at tech things, and I am wondering how this would work for what I have in mind. I originally was going to buy RGB light strips for the insides of my drums that pulse or strobe, etc. Seeing this thread though gave me a much better idea. How exactly does it work. For instance, could I program this to cause the light to activate every time I strike a drum?

GraziCNU (author)  schwaigor4 months ago

You can use this exact set up for that. The sound impact sensor has a sensitivity dial. If you put it in your kick drum, just decrease the sensitivity so it only picks up the kick head and not any tom or cymbal noise.

BryceN5 months ago

So to be honest, I cant entirely be bothered with learning the Arduino code, could someone copy and paste a code that will look sweet? Cheers (y)

GraziCNU (author)   BryceN4 months ago

With a functionality other than what this project defined?

I have the code in text that you can copy and paste in step 6 if you wish to use that.

Matkezi4 months ago

Nice man :) However, is 9VDC 650mA really enough to power 5M LED strip. As I read through the net I come up with 12VDC 5-6A power supply is needed? Thanks :)

GraziCNU (author)  Matkezi4 months ago

The Arduino Uno works up to 20V. I just had a 9V wall it was a work with what you have scenario haha. The lights were a little dimmer at the lower voltage but it got the point across :)

mgarland29 months ago

Super easy to follow, GREAT detailed instructions and videos, a solid project for a beginner. Thanks!

GraziCNU (author)  mgarland24 months ago

Thank you for the feedback! I really appreciate it!

megadarkwood8 months ago

would it be possible to do this but have a 3.5mm input and output? so you can use headphones?

GraziCNU (author)  megadarkwood4 months ago

The lights can be triggered from a 3.5mm audio jack as opposed to sound impact sensor (its actually more accurate than this method but I just haven't tried on my own). I'm sure if you use a headphone splitter you could get the signal to the LED and listen to the actual audio track.

notjohn138 months ago
Is it possible to not use a breadboard in this project
GraziCNU (author)  notjohn134 months ago

Absolutely! I'm actually planning on moving this set up into a pumpkin head to wear around for halloween. The light will be triggered by my voice.

schristie57 months ago

Great instructable. Easy to follow. I'm new to the whole arduino and coding . I made this with just a simple rgb led but only used the red led to follow along with your tutorial. How would you go about coding the other to outputs into the sketch.

Eventually I want to get it to fade between the colors while it reacts to sound.

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