Increase LED rope brightness on small intervals

Discussion in 'The Projects Forum' started by sklide, May 6, 2014.

  1. sklide

    Thread Starter New Member

    May 6, 2014
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    0
    Hi everyone! I'm new here and getting back into circuits. I'm working on an LED light organ. I attached the schematic, it's pretty simple. It hooks up to a 3.5mm audio input and flashes some LEDs when the bass in the song hits. I'm using LED strips from this website here for my lighting

    I've got it working just fine, with only one minor problem. Since the bass hits are so brief, the lights don't become very bright. They only make it to about 20% of the brightness compared to when a constant 12v is hooked up. How do I make the LEDs reach their full potential in such short bursts?
     
  2. #12

    Expert

    Nov 30, 2010
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    Add a capacitor somewhere in the detector circuit to make the, "on" time last longer.
    You can't just jack up the voltage because, some day, somebody will have a lot of bass playing and the LEDs will smoke.
    You can get inside the detector and change the timing or add a pulse stretcher between the detector and the light string.
    Got schematic?
     
  3. sklide

    Thread Starter New Member

    May 6, 2014
    4
    0
    Hi! Thanks for the reply, I thought I attached it but it looks like it dissapeared. You can download it here.

    Would it be the 22uF one that I would need to increase? Any suggestions on a good value?
     
  4. #12

    Expert

    Nov 30, 2010
    16,343
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    Yeahbut...the 2.2 uf (C10) at the output of the op-amp has to pump the current that the 22 uf (C13) stores and it has to get rid of the current through the 39k resistor (R12). Then there is no limiting resistor on the base of the transistor so the current that does get pumped has no limit escaping through the transistor.

    I'm thinking more like this:
    Edit: This is designed for 20 times as much "on" time. If it holds too long, you can add a dump resistor in parallel with the 470 uf capacitor. Somewhere in the neighborhood of 500 to 1500 ohms. If you're a hobbyist, you can mess about with smaller capacitors.
     
    Last edited: May 6, 2014
  5. sklide

    Thread Starter New Member

    May 6, 2014
    4
    0
    Thanks so much for your help! It took me a while to get the parts in, but I got it working with your help. 470uF turned out to be too much. With both of the capacitors set at 47uF it works like a champ! Well at least when the audio is at a certain level. I posted a new thread here if you have any ideas on leveling out the audio input.
     
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