Sound Reactive Light




Hi, I will show you how to build sound reactive mood light using only Arduino Uno, RGB LED strip and a few common electronic components.

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Step 1: Materials Needed

  • Arduino Uno
  • RGB LED strip (common anode)
  • breadboard
  • LM358
  • 12V DC power supply
  • 9V battery
  • power cable for arduino (9V battery connector, power jack plug, cable)
  • 3.5mm stereo jack plug
  • 3.5mm jack splitter
  • wires
  • solder


  • 3x BD139 or similar (for longer strips you should use more powerful transistor + heat sink or RGB LED strip amplifier, you can edit the cirquit and use MOSFET too)


  • 2x 10 uF
  • 1x 47 uF
  • 1x 47 pF


  • 1x 33 kΩ
  • 2x 100 kΩ
  • 1x 1 kΩ
  • 3x 150 Ω
  • 3x 5.1 kΩ

Step 2: Wiring

For wiring up components on a breadboard just follow the schematic. For transistors I've used universal PCB, because mine have too strong connections.

Signal is connected to the left channel contact of the jack connector, but you can use right instead. Ground is connected to the ground of the connector.

As a source of 12V you can use some 12V DC power supply or lead-acid battery, but keep in mind that 1 meter of RGB LED strip can consume up to 15 watts.

Arduino onboard LED indicates limitation, if it is flashing, you should replace R1 with resistor with less resistance (10 kΩ).

Step 3: Programming Arduino

It is using Arduino FHT library, just download it, unzip into Arduino libraries folder (Documents\Arduino\libraries\) and restart Arduino IDE.

After library installation you can upload the programm.

If you want, you can change speed of the fade effect by modifying DELAY constant.

I am using blue for low tones, green for midtones and red for high tones, it can be changed by swapping LED_R, LED_G and LED_B in setup function.

Step 4: Completed Project

Now you can connect power to arduino and LEDs. After that LED strip should light up and react to a signal comming from the audio jack.

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    2 Discussions


    4 years ago on Introduction

    The reactivity is very subtle, yes? I didn't see any red tones. Still a very pretty and soothing light and music. Thanks for sharing! I hope to see more Instructables from you in the future!

    1 reply