[sdiy] Noise-generating ICs

[James Patchell]

I am not familiar with the S2688, but the MM5837 I am well acquainted with 
(I even have one...I think)...This is not a great noise generator.  When 
you listen to it, you can literally hear the pseudo random sequence 
repeat.  It is, in fact, not even subtle.  It sort of hits you over the 
head like a two by four.  You can build a pseudo random noise generator 
fairly easily out of four 74HC164 shift registers and a 74HC86 XOR gate.  I 
am sure other list members can even point you to circuits.

http://www.silcom.com/~patchell/synthmodulesII/200-1021.pdf

Is the prelim schematic of one I started.  Better hurry, however.  Tonight, 
in theory, is the last night my web page is going to be up.  I turned off 
that account a couple of months ago, and tonight is the last night.


At 09:43 PM 8/31/2003 -0400, Robotboy8 at aol.com wrote:
>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

         -Jim
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