Adding LEDs to this Color Organ

Discussion in 'The Projects Forum' started by Jacketfan89, Feb 11, 2012.

  1. Jacketfan89

    Thread Starter New Member

    Feb 11, 2012
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    So, I've just began working with circuits, and I want to build this color organ. It is powered by a 12v source. Audio signal comes in and is split through 3 filters then each of the 3 signals (high, mid, and low) go to a transistor which powers 3 different color sets of LEDS. It looks like a pretty cool project, but I had one question. Would there be a way to add more LEDs? I know from the calculator I could easily get 27 if I had 9 rows of 3 in a series and broke them up into 3 blocks of 9 instead of the original blocks of 4?

    I just dk if the 12 volts are split up to 4, 4, and 4 into each transistor, which would not allow for a larger square array or if the 12 volts run through the whole circuit, if I would need to change anything (transistors or power supply) to increase the number of lights?
     
  2. Jacketfan89

    Thread Starter New Member

    Feb 11, 2012
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  3. Audioguru

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    Dec 20, 2007
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    Each 2N3904 transistor can turn on a power P-channel Mosfet that can drive hundreds of LEDs.

    The filters are very poor. They have a narrow peak.
    I simulated the bass filter. It gives a useable response from 130Hz to 230Hz so deep bass sounds will not light the LEDs.

    The mid frequency filter has a useable response from 700Hz to 1200Hz so most mid frequency sounds will not light the LEDs.

    The high frequency filter has a useable response from 3kHz to 5kHz so most high frequency sounds will not light the LEDs.

    I think the bass filter should be a lowpass filter so its output has ALL bass frequencies.
    I think the mid frequency filter should be a highpass filter and a lowpass filter so its output has ALL mid frequencies.
    I think the high frequency filter should be a highpass filter so its output has ALL high frequencies.

    The virtual-ground opamp is not needed since the opamp (+) inputs have extremely high resistances. It can be replaced with two 10k resistors and a 47uf capacitor.
     
  4. Jacketfan89

    Thread Starter New Member

    Feb 11, 2012
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    Wow! Thanks for the help. I'm really glad I came here now. I figured with a little help, I could make this thing a lot better.

    I am going to do some research on the low pass and high pass filters.

    Did you watch the video on the project page? If you scroll to the last minute you can see their's in action. I was wondering if the narrow peak on the filters is what gives it that almost pulsating look?? If so, that's kinda what I'm going for.

    I'm afraid if I use only lowpass and high pass filters the lights won't move with the music quite as well. I could be wrong though. Using the broader filters may still give the same effect.
     
  5. Jacketfan89

    Thread Starter New Member

    Feb 11, 2012
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    Also would I just connect each transistor to its own MOSFET and then that to however many LEDs I decide on for each channel? Also what is the best way to calculate resistor sizes since each block of lights has a different voltage?
     
  6. Audioguru

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    Dec 20, 2007
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    I simulated a mid frequency filter which uses a highpass and a lowpass. It responds to mid frequencies from 300Hz to 4khz. A lowpass filter will respond to bass frequencies below 300Hz and a highpass filter will respond to frequencies above 4khz.

    They selected "music" that was pulsing hammering sounds. The very simple filters will perform poorly with real music.

    A good circuit will show what the music is doing.
     
  7. Audioguru

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    Dec 20, 2007
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    1) Select a P-channel Mosfet that can handle the current (most can).
    2) Add a 1k resistor from the gate pin to the source pin of the Mosfet to turn it off.
    3) calculate the current-limiting resistor for the series'd LEDs.

    You use simple arithmatic with Ohm's Law.
     
  8. Jacketfan89

    Thread Starter New Member

    Feb 11, 2012
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    300 hz is perfect for the bass. I am trying to calculate a bandpass filter for the mids to keep it between 300hz and and 1.5 kHz. And then highs > 1.5k I want to make sure the highs lights go crazy too, and I'm not sure if there's a lot of 4000 hz tones in music? You're the audio guru though. My goal is to improve this project by adding and rearranging/mounting the LEDs on some kind of reflective surface. If you think I'll get enough action outta the highs starting at 4kz let's do it!
     
  9. Audioguru

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    Audio is from 20Hz (a very low pitch) to 20kHz.
    Right now I played 300Hz then sang as high a pitch as I can and I can barely reach 300Hz with my highest voice. Bass sounds go down one octave to 150Hz, down another octave to 75Hz (the lowest pitch I can sing), down another octave to 37.5hz that my hi-fi can produce but my little pc speakers cannot then down almost another octave to 20Hz.

    Right now I played 4kHz and it is a fairly high pitch. I can whistle as high as about 2kHz. One octave above 4kHz is 8kHz which is a very high pitch and up another octave to 16kHz which is an extremely high pitch that my pc speakers cannot produce or maybe I can't hear that high anymore because I am an old geezer.
     
  10. Jacketfan89

    Thread Starter New Member

    Feb 11, 2012
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    Haha not old, just wise. I listen to a lot of classic rock and classic metal. I want the drums and bass to activate the low lights, the vocals and rhythm instruments for the mids and the higher pitched instruments/guitar solos to activate the highs. Would you say my ranges listed in the last post are feasible? Also, what program are you using to simulate these filters? I would like to use something as such. Many of the calculators call for variables that are unknown to me such as Q, and RL.
     
  11. Audioguru

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    Dec 20, 2007
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    I use the free simulation software LTspiceIV from Linear Technology.
     
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