making lights blink to music in car

Discussion in 'The Projects Forum' started by jdub1, Jul 28, 2010.

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  1. jdub1

    Thread Starter New Member

    Jul 28, 2010
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    ok guys, i've been struggling with this for two days, and i think i need some help. I am trying to get a 12V LED strip to blink to the beat of my sub woofers. This is my first post on this site, and first attempt at making my own circut like this, so bear with me. This is what i have:
    http://i233.photobucket.com/albums/e...chematic-1.jpg
    My problem is that my subs seem to only be getting direct current. They are pushing out way farther then they usually do or if i switch the leads off the amp, they suck in. The light illuminates with the music as it should, but i'm worried about the subs and amp.

    What's wrong? as simple as you can put it if you could [​IMG]

    (just for clarification, the negative AC off the rectifier is going to the amp, and the negative DC is going to the voltage regulator.)
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    Truth to tell, I would never use my amp speaker outputs to drive LEDs. There are no real ups for it, and lots of downs (such as extreme distortion, and the possibility of damaging the amp itself). I would use a powered module to drive the LEDs that goes between your amplifier output (which is also the speakers) and the LEDs. I've designed such modules.
     
  3. Audioguru

    New Member

    Dec 20, 2007
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    Your amplifier has DC on its outputs because your nightmare of a circuit has blown it up.

    Your "schematic" is un-readable.
     
  4. t06afre

    AAC Fanatic!

    May 11, 2009
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    Using a Color Organ in your Vehicle. Especially while driving is probably Illegal and definitely distracting. Try to google "12 volt light organ" it should at least give you some pointers to start with. Also read this http://forum.allaboutcircuits.com/showthread.php?t=40361. If your thread get closed, you will still be welcome to post on the forum. Just as you know it ;)

     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
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    How big is that LED strip?
     
  6. t06afre

    AAC Fanatic!

    May 11, 2009
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    A good question. If you have big LED strips blinking in the back of your car while driving it may be interpreted as brake lights from other drives. And hence cause unwanted situations. You should consider your plans
     
  7. beenthere

    Retired Moderator

    Apr 20, 2004
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    Exactly the point. It becomes a distraction and a safety issue.
     
  8. campeck

    Active Member

    Sep 5, 2009
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    could you use an opamp connected to the output of the amp as a voltage follower and input that into an lm3914?
     
  9. jdub1

    Thread Starter New Member

    Jul 28, 2010
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    The amp is not blow up, because when i disconnect the circut it is fine. I didnt post this for ridicule, the point is to get help and suggestions on my FIRST circut.

    its a blue 12V strip about 12 inches long.

    It's under my dash. no one willl see but but the people in the car. I have it wired to a switch and they are on at night all the time. Guys, i didnt come for a safety lecture, i knew that its illegal, and a "distraction" if you could even call it that. I just want to know how to design such a circut.
     
  10. jdub1

    Thread Starter New Member

    Jul 28, 2010
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    What is an opamp? where could i get one?
     
  11. jdub1

    Thread Starter New Member

    Jul 28, 2010
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    how do you design one of these? do you have a schematic? or is it something i buy?
     
  12. campeck

    Active Member

    Sep 5, 2009
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    http://talkingelectronics.com/projects/OP-AMP/OP-AMP-1.html

    Radioshack.

    Basically I am talking about using an opamp as a buffer. hook it up as a voltage follower. the output feeding directly back into the inverting input. and the non inverting hookup connected to the positive output of the amp. Since opamps are high impedance it shouldn't affect the amps or subs. Then hook the output up to a transistor that turns on the LED bar.

    Ill draw a schematic.

    Also what is the current and forward voltage of your LED bar?

    BUT FIRST! DON'T BUILD THIS UNTIL BILL OR AUDIOGURU CHIMES IN.
    I AM NOT RESPONSIBLE FOR THE DESTRUCTION OF YOUR AMP. YOU HAVE BEEN WARNED
     
  13. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Wow, welcome to AAC. Did you read the sticky notes?

    John
     
  14. Audioguru

    New Member

    Dec 20, 2007
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    What happens to the input of your opamp when the 200W (or more) sub-woofer amplifier feeds it plus and minus 40V peak (or more)?
    Your opamp might melt and become a dead short to the amplifier.
     
  15. campeck

    Active Member

    Sep 5, 2009
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    I thought it looked too easy. Is the voltage just too much for the opamp?
    What does the wattage have to do with it? I thought that's just a calculation based on the load resistance and current?
     
  16. beenthere

    Retired Moderator

    Apr 20, 2004
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