[sdiy] Noise-generating ICs

[Ray Wilson]

Re: [sdiy] Noise-generating ICsHi Grant

Not at all, I appreciate your input. I did not consider that R5 would
attenuate the signal but rather only intended it to hold the high input
impedance non-inverting input from floating about. The frequency content of
the noise should improve (have more low end) with a larger R so I changed it
to 1M. I'll bet anything up to 10M would probably work as well.

Thanks for your observations.

Ray
  -----Original Message-----
  From: Grant Richter [mailto:grichter at asapnet.net]
  Sent: Monday, September 01, 2003 12:33 PM
  To: Ray Wilson
  Subject: Re: [sdiy] Noise-generating ICs


  Are you sure you want R5 at 4.7K? Perhaps a typo for 4.7M?

  As drawn, the circuit is feeding a 4.7 MEG source impedance into a 4.7K
receiver. Seems like it would form quite a voltage divider for the zener
noise signal.

  Nice circuit, sorry to be a butt-in-ski.


    From: "Ray Wilson" <rayw at csd.net>
    Date: Mon, 1 Sep 2003 08:47:53 -0600
    To: <synth-diy at dropmix.xs4all.nl>
    Subject: RE: [sdiy] Noise-generating ICs




    Robot Boy (Your AOL box is full) regarding noise...

    You want noise... Go here:

    http://atlas.csd.net/~rjwsoft/multinoisemodule_exp.html

    Ray

      -----Original Message-----
      From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Robotboy8 at aol.com
      Sent: Sunday, August 31, 2003 7:43 PM
      To: synth-diy at dropmix.xs4all.nl
      Subject: [sdiy] Noise-generating ICs

      Hi, I think this is my first post but I've been lurking for months
now.
      I'm looking to build an electronic drumset using a noise source split
into several identical channels, filtered, and mixed back together.  The
trouble is, the book I'm getting the basics out of (Build your Own Low-Cost
Signal Generator, by Delton T. Horn) lists two ICs for noise generation, the
MM5837N and the S2688, but a Googling shows that neither are easily
available.  Can anyone here point me towards another suitable IC?
      As background, I'm building a simple drum machine as a first sdiy
project (not very synth, i guess, but a good start).  I haven't purchased
many components yet because I want to make sure they're all available - so
far, that's the only one that's not.
      Also, are there any reasonable alternatives to optoisolators for
voltage-controlled resistors?  How is voltage control usually handled in
synths? (this one's been bugging me for a looong time...)
            -eric




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