Sync Leds with music

Discussion in 'The Projects Forum' started by cree247, Nov 2, 2010.

  1. cree247

    Thread Starter New Member

    Sep 1, 2010
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    I have 2 parallel led strands that I am trying to connect with the left and right channels of an audio source. Each strand has 100 leds in parallel with each other, they also have a 330Ω resistor in series with each led. The leds run on a 5 vdc source. Does anyone have a circuit that I can connect to one strand for the left channel and another for the right so that the leds move with the music?
     
  2. R!f@@

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    Do u want to move 100 leds
     
  3. Bernard

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    Aug 7, 2008
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    Might try using a full wave bridge rectifier on the 4 Ω amplifier output. Connect + led string to cathodes, - to anodes. Will need about 10
    W max.
     
  4. Wendy

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    Mar 24, 2008
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    LEDs, 555s, Flashers, and Light Chasers

    Chapter 12

    [​IMG]

    You can not use a single strand with 100 LEDs. That works out to 250V for red LEDs, and 360V for white. I strongly recommend you read chapter 1 and 2.
     
  5. thatoneguy

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    Do you have a schematic of the 100 LED strand?

    The way you describe it, there are 100 resistors in it? That seems a bit... inefficient..
     
    Last edited: Nov 2, 2010
  6. R!f@@

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    Oh boy,Oh boy,Oh boy,Oh boy,..OP's gonna need lotta LM3914 or 3915's
     
  7. Wendy

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    Nope, the circuit I put up there would work. He's gonna need a lot of resistors though, the MOSFET can drive them all if it is a decent unit (different part number than Radio Shack sells). For 99 LEDs it would be 33 resistors and 33 legs.
     
  8. R!f@@

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    Hey is tht a full wave rectifier...the all band ....no loss kinda ckt.
    If so. which is it, Log or linear..
     
  9. Wendy

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    He may have wanted a bargraph, it isn't completely obvious. I was thinking color organ.

    The OP can use a LM3914/LM3915. They are designed to be chained together, so he could have a 100 LED string.

    At this point we're just going to have to wait for a response from the OP.
     
  10. cree247

    Thread Starter New Member

    Sep 1, 2010
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    Don't have a good schematic of the circuit, just made one in paint. It has 100 leds and resistors all connected in parallel like this. Runs fine on 5 volts dc.[​IMG]
     
  11. cree247

    Thread Starter New Member

    Sep 1, 2010
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    Yeah I was thinking of doing something like a color organ, 1 strand for high frequencies and the other for low.
     
  12. Wendy

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    Then all you would need to add to the one I provided (example B) is audio filters and you should be good to go. The link I provided explained how to do it in several chapters, you need something PWM for best efficiency.

    I also draw my schematics in Paint. You can download my templates on my blog here on AAC.

    Bill's Index

    Introduction and PaintCAD
     
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  13. jimit

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    Oct 28, 2010
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    i can help you try this i also used this for my lights
    [​IMG][​IMG][/URL]%20%20Uploaded%20with%20ImageShack.us[/IMG]
    do this twice for both left and right
    That transistor is a tip31.
     
  14. jimit

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    Oct 28, 2010
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    try this circuit i made my lights with this one only
    http://yfrog.com/6xmusicledp
    just do it twice both for left and right in one audio jack
    That is a tip31 transistor
     
  15. Wendy

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    That will definitely beat with the music, which may be all the OP wants. It doesn't modulate well with the intensity though (more of a on/off, with minor in between), and there are some key parts missing from the schematic, such as the base resistor.

    It has the advantage of brute simplicity. It also won't be able to drive 100 legs by itself. If each leg is 0.02A (a standard current for LEDs) 100X that is 2A. It will get hot, very hot (PWM tends to run a lot cooler).

    Looking at the TP31 datasheet it is a low gain transistor (as in not a Darlington), it will require around 200ma drive input for the transistor to cover the full range. Did I mention it will get hot?

    If you read the article in the link I gave you have some idea what is involved with LEDs in general. Higher voltages for the power supply is better, 12V-15V will simplify things a lot, and reduce the total current (a good thing, less heat, less input drive).
     
  16. cree247

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    Sep 1, 2010
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    I did try the circuit with the tip31 already, but it didn't give enough power to the lights so they were sort of dim when the music played.
     
  17. R!f@@

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    I see tht OP is getting no where...

    OP, what is it exactly tht u want?
     
  18. thatoneguy

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    Do you have a schematic of the circuit you tried with a TIP31 with sub-optimal results?

    There are several designs existing, some created and tuned in just the past two weeks.
     
  19. Wendy

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    Mar 24, 2008
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    Pretty much as I described. If all you want is a blinking LED then a transistor by itself will work, but for performance you need the extra circuitry.

    The old color organ of the 60's didn't just blink full on and off, it had intensity according to the sound level. This could be done with a op amp and a single BJT transistor (such as the TIP31), because of the shear number of amps you are going to need gain.

    I'll see what I can come up with that is simpler.
     
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