RMS to DC Converter

Discussion in 'General Electronics Chat' started by Sparky49, Sep 16, 2014.

  1. Sparky49

    Thread Starter Active Member

    Jul 16, 2011
    834
    417
    Hi all,

    I've been thinking about making a nixie tube graphic equaliser in my head. It would make sense that the scale displayed on the nixie bar graph would be log, or than is how our ears perceive loudness. I did a bit of research, and came across RMS to DC converter ICs, which seemed to do this quite well, however, they also cost quite a bit, especially when you consider buying one for each nixie tube.

    Is there a means by which one can make an RMS to DC converter cheaply (<$5)? Or is there perhaps another way that could achieve what I am after?

    Many thanks for your time,

    Sparky
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,136
    1,786
    I don't think RMS is what you want. I think you transformer couple the audio signal, rectify it and peak detect it with a fast attack and a slow decay. Think of the opening to the 9th Symphony. Three staccato attacks followed the decay. In RMS it will look like mush.
     
    Last edited: Sep 17, 2014
    Sparky49 likes this.
  3. Lestraveled

    Well-Known Member

    May 19, 2014
    1,957
    1,215
    I agree, RMS is not what you want. A good peak detecter with an adjustable decay would work well for your application. A search for "op-amp peak detector circuit" will give you a lot of examples and even a youtube video or two.
     
    ScottWang and Sparky49 like this.
  4. Sparky49

    Thread Starter Active Member

    Jul 16, 2011
    834
    417
    Perfect, many thanks guys.

    Peak detector it is. :)
     
  5. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    Don't forget the bandpass filters. You'll need a bunch of them too.
     
  6. bertus

    Administrator

    Apr 5, 2008
    15,645
    2,344
    ScottWang likes this.
Loading...