[sdiy] Digital Noise, FYI

[Graheme Wilson]

There is a good circuit in a book called Practical Oscillator Circuits
by A Flind.

I have built it and it works really well.

It uses two CD4006 shift registers and a 4070 XOR.It is clocked at
1.4mhz. The circuit is a 33 stage register with a tap at stage 20. He
takes the tap and XOR's it with stage 33 and feeds it back into the
input.The sequence runs for over two hours before it repeats.


Graheme


On Wed, 2011-02-16 at 08:38 -0500, Harry Bissell wrote:
> hmmm...
> 
> When I got my ProphetV, it used the dreaded (and feared) MM5837 noise source.  I tried to make an exact
> replacement with analog techniques, but could not get the 0>15V "all or nothing" voltage swing. I suppose
> with my superior skills these days, a comparator would have done the trick...
> 
> A CD4006 based solution was exactly what the doctor ordered, it did not mess up the factory presets in the least, but
> removing the MM5837 did eliminate the (your choice) <ticking time-bomb> <roaring freight train> <chinese water torture>
> from the sound...
> 
> The digital techniques have their place. I don't really care about 'random'... a repeat every few hours or so doesn't
> get too much of my attention :^)
> 
> H^) harry
> 
> 
> 
> ----- Original Message -----
> From: karl dalen <dalenkarl at yahoo.se>
> To: Synth DIY <synth-diy at dropmix.xs4all.nl>, Matthew Smith <matt at smiffytech.com>
> Sent: Wed, 16 Feb 2011 05:31:46 -0500 (EST)
> Subject: Re: [sdiy] Digital Noise, FYI
> 
> If you replace that CPLD *thing* with an analog one FET based S/H
> and one NPN based noise source you end up with a cheaper and 
> simpler and better sounding result.
> 
> Did i mention Moog Source envelopes?
> KD
> 
> 
> >Matthew Smith <matt at smiffytech.com>:
> 
> > ...
> > >> 555 -> CPLD -> 10-bit parallel load DAC
> > 
> > I actually got that a bit wrong - it's a 12-bit DAC, the
> > MX7541, which is just a Mexican version of the AD7541 ;-)
> > (Not really, it's the Maxim version. Just my silly joke.)
> > 
> > > That's an awesome circuit, from an awesome book. 
> > It's high on my to-do list
> > > as well.
> > 
> > I'd recommend Lancaster's books to anyone in this field -
> > he's a really good teacher, it's just a shame he never
> > published more. I have the TTL Cookbook, CMOS Cookbook,
> > Active Filter Cookbook.
> > 
> > To address Dave Manley's question, yes. String of flipflops
> > with some XOR gates. (Photo of relevant page mailed to
> > Dave.)
> > 
> 
> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
> 


-- 
Listen to Paladin by Vicia Faba
http://viciafaba.bandcamp.com