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Music Rhythm LED

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This simple circuit will make LED diodes flash as music plays....

It supports stereo. There are two diodes, one is for LEFT INPUT, secondary is for RIGHT INPUT.

What you will need?

  • 1x Stripboard or something where you can assembly this circuit (I assembled it on piece of cardboard - I'll make tutorial later how to make PCB on piece of cardboard)
  • 2x or more - any color bright LED ( I used 2V green bright LED's)
  • 1x - 562Ω resistor (Or min 400Ω)
  • 2x - Any general purpose NPN transistor should do the trick.
  • 1x - STEREO Audio cable with 3.5mm jack
  • 1x - STEREO Audio 3.5mm output jack

R1 - 562Ω

D1 - Green bright LED

D2 - Green bright LED

Q1 - NPN General purpose

Q2 - NPN General purpose

I used 8050 transistors for Q1 and Q2.

If you want to increase or decrease LED's brightness, increase/decrease value of R1. Also you can put variable resistor:

- R1 should be 50Ω then. This is needed to prevent LED's damage if variable resistor is on minimum resistance.

New circuit will be: |+5 to +12VDC|-----------|R1|-------|VARIABLE RESISTOR|

How it works?

Q1 and Q2 are NPN transistors, connected to act as switches.

Their bases are connected to the AUDIO IN.

When an audio signal rises, they allow current to flow through them.

How much power will they allow to flow through them depending of audio signal intensity.

R1 is here to prevent damage to LED's if current is so high. Also it protects Q1 and Q2 from begin damaged.

Here is the scheme:

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And here is two ways to add more diodes:


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Warning: If you add more diodes, higher current will need to flow through transistors, if they are not rated to that current, they may get hot and even worse, damaged.

Transistors max current depends on LED-s ratings.

R1 - You may need to adjust it's resistance, depending on input voltage, LED-s connection (parallel or serial) and LED-s ratings.

Plug it in on any DC power supply which have ratings between 5-12V, for maximum enjoyment use 12V because LED's will be brighter..

After all, plug it in on your computer, and plug in your speakers into 3.5mm audio out on your new circuit.

Play some music..... Notice LED's flashing in music rhythm :P

Enjoy :dribble:

Feel free to ask me if you need help.

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Is nice to find this kind of information here, i m engineer i just finished the college, your circuit is nice and simple:)  Also you can use a breadboard if you don`t know how to handle a ledcon

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