Color Organ

Discussion in 'The Projects Forum' started by jlangho, Feb 7, 2012.

  1. jlangho

    Thread Starter New Member

    Oct 22, 2011
    Found a thread similar to this here that pointed me to the same schematic I've got, here:


    Probably going to order the IC's i need off of digikey and give it a whirl here sometime soon.

    Couple things I'm planning on doing though:

    1) microphone as audio source
    2)eq style light bars

    I'm thinking for (1) that I'll be able to wire in a MIC to the input pins but I'm not sure how much (if any) amplification of the mic will be needed. There really were no application notes in the datasheet. Here's the one i have picked out: MIC

    (2) is a little more complicated. I'm hoping that I'll be able to use a LM3914 to drive LED's like light bars instead of the 2n3904 driving LED's as shown in the circuit. I'm just not quite sure of the output of the circuit. I'm guessing its a logic high/low output which in that case i would not be able to use the driver. I just haven't had enough time lately to simulate it and see, was wondering if anyone could shed light on it.
  2. SgtWookie


    Jul 17, 2007
    1) That is an electret mic, and you'll need an amplifier specifically for it.

    Here is a link to such an amplifier that you can build:
    One change: Replace VR1 with a 500k pot (you probably won't find a 470k pot).

    2) The LM3914 output is a current sink. You'd remove the 2N3904 transistor below the LED's. Don't plan on sinking a lot of current using the LM3914; if you want to go over ~10mA or so, you should use one PNP transistor per output to source current to your LEDs; have the LM3914 sink the current from the base. You will need base return resistors on the PNP transistors.
  3. jlangho

    Thread Starter New Member

    Oct 22, 2011
    using the PNP's is something that i anticipated needing. However my main concern was the output of the filter circuits. If it would be something that the LM3914 would be able to use.