MM5837?

[Magnus Danielson]

From: patchell <patchell at silcom.com>
Subject: Re: MM5837?
Date: Sat, 02 Sep 2000 12:22:18 -0700

>     All I can say is, good luck.  In one of my home made synths, I am pretty
> sure I have one of these things.  You might be able to talk me out of it as a
> last resort (I personally don't really care much for it, you can hear it
> repeat, if you listen really carefully).  These went out of production a long
> time ago.  Keep me posted if you can't find one.
> 
>     -Jim
> 
> Romeo Fahl wrote:
> 
> > Hello,
> >
> > I'm looking for an MM5837 ("Chugga Chugga") pseudo-random noise IC to do
> > some experimenting with.  Does anyone have a spare or know of a source for
> > one?

Do you really require the MM5837? It is not too complex to cook up a noise
source out of standard CMOS or TTL. If you go to the archives (Oh, I never
thougth I would refer to them!) you will find a thread on the subject, I recall
being part of it, I even posted a ASCII schematic in there...

If you really want a a 17 stage noise source it should not be too difficult to
make an equalent schematic, but a longer shifter is better. A 4006, a XOR gate
of choice and some clock generator (two of the XOR gates could be used for
that) and you have an equalent.

The MM5837 is a 17 bit shift register with feedback at the 14th tap. The MM5837
also has an internal oscillator which changes frequency with the supply power
(obviously!). Getting something equalent should not be too hard. Actually,
a 17-tap shift register is a bit too short... it will beat too obviously.

Anyway for some more info, check out:
http://www.vego.nl/8/18/8_18.htm
http://www.io.com/~ritter/NOISE/NOISRC.HTM

Cheers,
Magnus