LED Flashing w/audio

Discussion in 'The Projects Forum' started by randname, Nov 14, 2008.

  1. randname

    Thread Starter New Member

    Nov 14, 2008
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    First off, I'm new to everything, so forgive me for not being very specific.

    I'm trying to set up an audio system with a ton of LEDs that flash with the music. I tried running the LED's in a series connected to my stereo but the volume needs to be way loud and I can't have as many LEDs.

    What I want to do now is create a near stand alone device that will flash the LEDs with the music, but is connected to its own power source, that way I can use all of the LEDs that I want.

    Is there any way that I can run the speaker wire into a device that that will not stop the music but will be able to detect voltage changes and open another switch to the LEDs?

    If not then does anyone have any other ideas?
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    You want just to turn on all the leds with the bass beat or turn on some leds each time depending on the sound volume?
     
  3. randname

    Thread Starter New Member

    Nov 14, 2008
    2
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    All at once is all I need.
     
  4. mik3

    Senior Member

    Feb 4, 2008
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    63
    Take a comparator IC (op-amp specialized to work as comparator) and connect its inverting input to a potentiometer. Also, connect one output of the stereo to a half way rectifier with a resistor in parallel with a capacitor on its output. Then connect the output of the rectifier to the non-inverting input of the comparator. Finally, use a power transistor on the output of the comparator to drive your leds (the power of the transistor depends on the number of leds).

    Note: the output voltage which drives the speaker may be high for the comparator and it will destroy it. I suggest you to use a voltage divider after the output of the rectifier to reduce the voltage down to safe levels and a zener diode on the non-inverting input of the comparator to protect it.

    Also, with the potentiometer you will be able to adjust the flashing depending on the volume of the stereo system.
     
  5. Dellash04

    New Member

    Dec 2, 2008
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    Hi i need some help modifying this circuit below. It flashes ok when it is on different power supples, but is in my car so it runs or the same. So when i connect it the sound stops coming through the speakers. Is there any thing i can add to stop that. because i probly have the same problem as above.



    Thankyou
     
  6. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    Its because you take the audio signal from the headphones plug. When you put the headphones plug into the radio there is a switch inside which makes the speakers stop playing and just hear from the headphones. Look if the radio has RCA outputs at the back side and use them. There is an RCA to normal audio plug converter, just a simple wire nothing special.
     
  7. Dellash04

    New Member

    Dec 2, 2008
    3
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    sorry for not being clear enough. but the circuit is conected to the rear speakers of my car. that is the problem the back speakers stop and the front are still proudcing sound when i conect the circuit.

    Thanyou
     
  8. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    If your circuit input is connected directly to the speaker then maybe a short causes the speakers to stop playing (most of the current flows through the short).
     
  9. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Modern car amplifiers drive both wires of each speaker. You probably connected one wire of a speaker to ground at the input of the LED flasher circuit.
    Connect only the live input and do not connect the input ground to a speaker. Instead, connect the input ground of the LED flasher circuit to 0V.
     
  10. Dellash04

    New Member

    Dec 2, 2008
    3
    0
    Thankyou for your help.
     
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