Audio Responsive LED Circuit Modification for Electret Microphone

Discussion in 'General Electronics Chat' started by McCaw, Dec 15, 2010.

  1. McCaw

    Thread Starter New Member

    Dec 15, 2010
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    I'm building a mask for a DJ that has LED lights embedded in it. These lights respond to audio input that is currently coming directly from a laptop.

    I need to modify the circuit (which operates on 9V) so the input is coming from a small mic instead of a computer. I was wondering if it was as simple as hooking up this kit into the circuit:

    http://www.canakit.com/electret-microphone-amplifier-kit-ck009-uk009.html

    Does this device have a spot to put a 3.5mm audio cord into it? I can't really tell from the photo. I'm assuming the kit can share power from the 9V battery that's running to the LEDs at the moment.

    Thanks for the help!
     
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    What you are looking for, I believe, is a "light organ" circuit, which lights up different LEDs depending on what frequencies the mic is receiving.

    They are comprised mostly of op-amps as an amplifier for your mic, and as active filters for the different frequencies. Add in transistors to drive the LEDs and it is complete. There are many variations of this.

    Another option is using a microcontroller, but that gets pretty advanced quickly if you aren't familiar with programming.
     
  3. Wendy

    Moderator

    Mar 24, 2008
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    You mentioned you already have the LED flickering. It might help if you show us what you have.
     
  4. McCaw

    Thread Starter New Member

    Dec 15, 2010
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  5. McCaw

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    Dec 15, 2010
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    oops, i meant: "will the transistors I have right now still work
     
  6. thatoneguy

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    Feb 19, 2009
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    The light organ /multi-channel circuit would be quite a bit more complicated than the one shown above. The amplifier you linked above should have enough output to run the TIP31, the LM386 will drive a small speaker, so it should perform at least as well as your video shows.

    Another thought, if this is for a knit cap, you may want to use "magnet wire" and SMD LEDs, if your soldering abilities are very good. They wouldn't really be visible unless on then, especially if embedded in the weave, but that would take a great deal of patience and time.

    Come to think of it, are you wanting to use the microphone to make the cap "wireless"/not tethered to the mixing board? The power source would need to be included, depending on required runtime, it might not be the most comfy for long run times.

    I'm basing ideas from Bill's circuit (single channel color organ) near the bottom of This Page
     
  7. McCaw

    Thread Starter New Member

    Dec 15, 2010
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  8. McCaw

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    Dec 15, 2010
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    and the power source is a 9V battery. I'll be testing everything to make sure it lasts long enough for my friend's music set
     
  9. thatoneguy

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    Feb 19, 2009
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    That kit would work fine.

    3 sets of LEDs wouldn't last over 20-30 minutes on a 9V battery, they are typically only around 150-300mAh. I'd suggest 6 AA batteries in series instead to get the 9V, or 8 AAs for 12V. A AA battery is usually upwards of 2000mAH.

    If this is at a fixed position and wires can be used, then a wall-wart power supply. If weight is a concern, look into Li-Po Rechargeable Lithium cells, they are relatively flat and have very high power density.
     
  10. McCaw

    Thread Starter New Member

    Dec 15, 2010
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    Thank you so much for your help!
     
  11. McCaw

    Thread Starter New Member

    Dec 15, 2010
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    If i'm looking into rechargeable AA batteries, will the voltage be the same, or will I need a different number of batteries? From what I can tell, the voltage is going to be pretty similar...
     
  12. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    For the first part of the discharge, the voltages will be within 0.1V or so. For the last bit, NiMH drop by 0.2-0.3V more than an alkaline would, but still function.
     
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