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LEDs Sync To Music

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by FreeTrial, Jun 6, 2006.

  1. audioguru

    audioguru Well-Known Member Most Helpful Member

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    The parts are $15.00 at RadioShack but are less than $5.00 at a proper electronic parts store.
     
  2. FreeTrial

    FreeTrial New Member

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    and what would be classied as a "proper" store??? I dont have much aruond here except for radioshack, and a hobbytown usa?
     
  3. audioguru

    audioguru Well-Known Member Most Helpful Member

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    www.digikey.com and www.newarkinone.com for starters. There are many more "proper" online electronic parts distributors.
    Look in your phone book for electronic parts or surplus stores near you.
     
  4. dave

    Dave New Member

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  5. headcracker

    headcracker New Member

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    hey audioguru

    can u furnish some details abt ur project......me trying to create a led network controlled by music (like music lights) for a project.....

    i mean it wud be a light decoration kind of a thing which wud vary light intensityaccording to the intensity of sound

    i read ur posts and thought that ur project wud be really helpful in mine
     
  6. audioguru

    audioguru Well-Known Member Most Helpful Member

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    What details? My circuit here is just a little power amp IC with DC biasing so that its output voltage without a signal is zero, and a rectifier followed by a pulse-stretching capacitor.

    The circuit I posted here works well controlling the intensity of LEDs with the loudness of pop music. Classical music has a very wide range of loudness and would need a much more complicated circuit.
    The little LM386 amp can drive about 18 LEDs each with a series current-limiting resistor. A power amp IC designed for a car would be able to power hundreds of LEDs. A power amp IC designed for a home would be able to power about one-thousand LEDs.
     
  7. headcracker

    headcracker New Member

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    thanks mate
     
  8. ferrari99

    ferrari99 New Member

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    hey,

    I built this circuit and i must say, it works great. I did a couple modifications to it though, i used a 100uF cap instead of the 220uF from the schematics because i found a bit of a delay with the light the sound (no idea if thats what affects the delay but it worked) and i also completely took out the 10K pot from the audio input.

    My question is though, i noticed the LED is only sensative to high pitched sounds (claps, singing etc.), I've tried many many songs on it and have come to that conclusion. How would I be able to tune it to be senstive to the bass instead of higher pitches? what part of the circuit affects that aspect. Thanks, any help is appreciated.

    Corey
     
    Last edited: Jun 26, 2006
  9. audioguru

    audioguru Well-Known Member Most Helpful Member

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    The circuit has nothing to cut its bass response. Make a lowpass filter with a series 10k resistor from the music source to the input pin 3 of the LM386, and a 0.1uF capacitor at pin 3 to ground.
     
  10. ferrari99

    ferrari99 New Member

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    thanks audioguru it worked great,

    just one thing though, im testing it on my mp3 player and put a splitter in the headphone jack so i could connect my headphones and also see the LED working to the music. When i connected the LED a first nothing happened until i shorted the left and right audio output to go into the audio input of the device. If i do that then i can only hear from one ear of the headphones. I guess the LED needs a stronger input. Is there a way of getting a stronger input and also being able to listen through my headphones? And also, since im preparing this for a stereo, and since stereos have a much higher output than small devices, how will i be able to take an output from the stereo and adapt it to the right input for this device. Thanks

    Corey
     
  11. audioguru

    audioguru Well-Known Member Most Helpful Member

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    The input of the LM386 can be connected to either channel's output and work fine. Maybe you connected the input of the LM386 to one channel's output and the ground of the LM386 to the other channel's output.

    The gain of the LM386 can be increased 10 times by adding a 10uF capacitor between its pin 1 and pin 8, positive at pin 1. The headphones should work fine if everything is connected correctly.

    A 22k resistor from the L channel and a 22k resistor from the R channel and their junction has a 560 ohm resistor to ground and is the input to the circuit. Then the level is reduced to about 1/20th.
     
  12. catcat

    catcat New Member

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    EUREKA!

    (this is an accidental invention.)
     

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  13. audioguru

    audioguru Well-Known Member Most Helpful Member

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    It is accidental, all right!
    The 1st 3 transistors don't do anything and the 4th transistor isn't biased correctly. The 3300uF capacitor has such a high value that the 4th transistor has a frequency response down to .05Hz. Only 3.3uF to 10uF is needed for audio.
     
  14. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    It looks like an 'mstechca' design - throw a random collection of bits together and see what happens :D
     
  15. ballpoint

    ballpoint New Member

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    hey audioguru does this look like a good little circuit? it seems to work but i need someones opinion http://www.runtimeerror.net/blinky/index.html i dont know if you'll even get this.. but if anyone does can you tell me if it might work or not, thanks!
     
  16. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Hi Ballpoint,
    This circuit is nearly as bad as the other one.
    1) If the music source has a coupling capacitor, then the LED is on without music.
    2) Music causes the transistors to be rectifiers that switch the LED off for each half-cycle of sounds.
    3) The LED doesn't get brighter when the music is louder then dimmer when the music is softer.
    4) The input of the 1st transistor is like a dead short to the music source.
     
  17. ballpoint

    ballpoint New Member

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    He had a video of it working on there though.. you're saying it wont work at all?
     
  18. audioguru

    audioguru Well-Known Member Most Helpful Member

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    It follows the music, sometimes.
    The LED is lighted when there is no sound.
    Sometimes sounds turn it off, sometimes they turn it on.
    The circuit doesn't know if it is coming or if it is going.

    In my circuits the brightness of the LED is the same as the loudness of the sound. Very short duration sounds are lengthened so that their loudness can be seen.
     
  19. ballpoint

    ballpoint New Member

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    yours did sound like a good circuit, but i couldnt follow what you were all saying.. im just a kid and dont know anything really yet but im trying. I looked at your circuit and it just confuses me.. this guys seemed simple and easy enough for me to understand. I can sort of make out what yours is doing but i dont understand most of it..
     
  20. audioguru

    audioguru Well-Known Member Most Helpful Member

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    My circuit simply converts the loudness of sounds into current for the LED.

    This is my Sound Level Indicator project with its 20 LEDs that display the volume of sounds and it has a microphone and a rechargable battery. It can pickup the sound of a pin dropping on the floor on the other side of the room, or a very loud bass beat. The 20 LEDs can be switched to turn on in a bar, or in a dot as shown here:
     

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  21. ballpoint

    ballpoint New Member

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    Thats cool.. but probably alittle too advanced for me right now, i was just bored and thought about geting some leds to pulse to music for fun.. i found this site and then read all that has already been posted. ill see what i can do, thanks for your help!
     

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