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LED Spectrum Analyzer Wall - College Project

Discussion in 'LEDs and Optoelectronics' started by scruffy3011, Feb 2, 2014.

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  1. scruffy3011


    Feb 2, 2014
    Hi all,

    I am currently building a LED wall that projects a spectrum analyzer for my college project.
    The wall will have approximately 200 LED's (20 Columns, 10 Rows) but can be altered.

    Please can people educate/advise me. My logic says it will be something like this:

    Input signal from 3.5mm jack
    20 Band pass filters to get the required frequencies for each column
    10 LM3915(Bar display drivers) for the LED's

    is there an IC to replace 20 band pass filters?
    lm3915 has a 0-30db range, is 30db high enough?

    ANY advice id appreciate, or links that may help me.

    Thanks in advance,
  2. BobK


    Jan 5, 2010
    Or, for a lower cost alternative, use a 44-pin dsPIC to run an FFT algorithm and multiplex the 200 LEDs.

  3. whiterabbit


    Sep 14, 2013
    This morning I've been looking into building some sort of display such as this for my home studio. I'm interested to see where this thread goes.

    I was also considering building a three-part display (left/right/sub) so I can keep an eye on all the outputs without having to fiddle around in my DAW too much :p I should probably start simple though...

    Out of curiosity, how big are you trying to make this? When I say 'big' I mean physical size, as opposed to # of LEDs. Have you found any reference material so far that you've been looking at?
  4. OLIVE2222


    Oct 2, 2011

    If allowed for your college project the Bob way will be indeed lower cost and moreover closer to what you can find in modern product.
    For the "old school way" yes 20 BP filters (maybe a LP for the first one and a HP for the last one) . Don't think that dedicated IC's are available. The LM3915 can be mapped as you want is a matter of how many db you want per led but a 30dB range looks OK

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