White and Pink Noise Generator

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BJT noise rev2
BJT noise rev4
40106 Experimenter Board


Super simple transistor based white and pink noise source.

Board image looks like this:

While Schematic is as such:

I have tested this version and it works. White noise outout is a bit low.

Files to download:

  • Eagle schematic file can be downloaded here
  • Eagle board for REV2 is here.
  • You can read either and make a gerber using Autodesk Eagle.

    About the REV2 design

    Like so many old noise boards, this one depends on noise inherent in a NPN transistor between E and B and amplifies it. I set things up so you can put test leads on the "Transemt" and "Transbase" test points and clip it to your 2N2222 or whatever transistor. Hook the output up to your amp and monitor and try out transistors until you like the way the white and pink noise sound. Once you have a winner, solder the "winning" transistor into the T1 location if you want.

    I can't remember where this design came from, I thought I saw something like it in an old tom henry design, but he might have swiped it from Electronotes? Anyway this is pretty much the "classic" way to get a good and truly random analog noise source.

    For the build I ended up using, I tried a whole bunch (I mean, many, many) transistors.The one I ended up using had really good sounding pink and white noise, but the white was about 12DB too soft, stange because P2P was about the same, about 2v, when viewed on a scope. If I was building this again I'd take the unused op amp and put it in series with the white noise out so if you don't want to gain the WN up, just make it into a buffer; if you do, add some resistors to get x DB of gain.

    Some of the things to mess with: R5 and R6 set the overall level for the pink noise. R10 and 11 for white. R1 and R4 set overall gain, you can set this for too much gain and get bad sounding noise. You can also cap couple the output--throw a 10uF cap on each output to make sure the noise centers around 0V P-P.

    REV 4 of the Transistor Noise Board

    This is a pretty minor revision, and I have NOT tested this working (yet). I added a 6dB boost via op amp on the white noise side. I am pretty sure I got this right....I just took one more unused stage of the TL074 and used it to boost the White Noise gain.

    FILES FOR DOWNLOAD again REV 4 isn't tested yet....

  • PDF of the REV4 board schematic is here.
  • You can get a PDF of a wiring diagram (not much for this circuit!) here.
  • Eagle schematic is here
  • Eagle file for the board layout is here.
  • I will not post gerbers yet until I test this board, but since REV2 worked and this is just one more op amp it should work fine I figure. Somewhere down the line I'll create the gerbers and send this off to fab, we'll see how it sounds.

    40106 based CMOS experimenters board

    I have been reading up on the work of Stanley Lunetta --interesting guy. In his honor I fabbed up a quick board you can use for 4x VCO's, LFOs or whatever.

    As a proof of concept I created a quad VCO using surplus optocouplers and wired up FM for 3 of the 4 stages. tests working! Turned into a useful and dare I say fun module. Don't expect smooth linear 1V octave tones or whatever, that is not possible from the 40106 which is highly sensitive to temperature as well as bad breath. Good for pitch sweeps, to feed other FM ins, and so on, the 40106 CMOS chip puts the modular in modular DIY. The FM ins are really interesting, you can get all sorts of geeky FX out of those. You can read more about this on my blog if you want.

    Here's the 40106 experimenter board:

    Schematic looks like this:

    You can get a zip of the Eagle Schem and Board layouts here.

    For both of you out there who want gerbers for this design here you go.