A viable solution[Was]Re: MM5837?

[patchell]

    Here I am listening to my chugga chugga (I found it, didn't even have to do so by
inspection, I just listened to it, it is a whole lot worse than I remember), and a good
solution to this problem is staring me right in the face.

    If you would all please turn to page 147 in the good book (Digikey-July-Sept 2000),
you will notice that the XC9536-15PC44C is only $3.30 in unit quantities.  It would be
entirely posible to put a 32 bit shift reg and XOR feedback into one of these little
suckers.  I just have to dig up the article I have stashed somewhere that shows which
cells to tap.  About a half hour at Xilinx Foundation, and I should have a hex file.
(Although, I will not be back at work until this Wedensday).  I would post the hex file
and schematic (and encourage others to post it on their site).

    Anybody interested?

    -Jim

Harry Bissell wrote:

> Likewise I have a schematic for one that I adapted from Popular Electronics.... and
> used
> in the Prophet V to replace the... (gawdawful) ... chugga chugga unit ! will send
> scan to
> any who requests...
>
> H^) harry
>
> Magnus Danielson wrote:
>
> > 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

--
 -Jim
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