Purely Analog Audio Spectrum Analyzer - Help.

Discussion in 'General Electronics Chat' started by erezMASTER, May 7, 2013.

  1. erezMASTER

    Thread Starter New Member

    Jan 11, 2012
    Hello guys,
    I am willing to build a LED based Music spectrum analyzer
    that will be based on a MCU.

    The idea is to do it purely Analog,
    simply because I dont know what is FFT at all.

    I am going to build it using Active filters, Peak Detector and an ADC.
    I'm going to address one at a time each row of the led matrix by turn and activate the required amount of LEDs according to the ADC output.

    Question is:
    Is it possible and worth the time?
    May you please give me some tips?
    (Note that I am a beginner.)

    Simple idea picture is provided.
    Thanks a lot :)
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    Here is the chip you need to do just that.

    Although it is called a Graphic Equalizer Chip, it only monitors incoming signal, filters for a specific frequency range, detects peak, outputs peak value, then indexes to the next frequency range, detects peak and outputs (repeat until top frequency range is exceeded and starts over).

    All you need is an 8 channel multiplexer, seven LM3915 / LM3914 chips to convert the output signal level their respective 10-Segment LED display. Seven bands of spectrum. Not bad for under $30 of chips.

    On the other hand, you might be able to pick up an old-school graphic equalizer at a second-hand store for $30. That graphic equalizer could do the same thing plus has adjustable filters for each band.

  3. Meixner


    Sep 26, 2011
    You should continue with the threads you already started, That way everyone will know what has already been done.
  4. erezMASTER

    Thread Starter New Member

    Jan 11, 2012
    Thanks for your reply.

    Thing is,
    the MSGEQ7 does all the work, I prefer to go a bit deeper that why I want to use an MCU.
    another reason is that this IC can drive up to 7 LED bands, while I intend to do a 16x20 Matrix.

    My older threads were confusing and went a bit off-topic, so this one will be oraganized. :)

    More replies are most very welcome.*