[sdiy] LFSR digital noise source

Ben Stuyts ben at stuyts.nl
Mon Nov 11 01:03:08 CET 2019


That link points to the mil-spec version which is $15 each at 100 pcs. :-D

Ben

> On 11 Nov 2019, at 00:43, rsdio at audiobanshee.com wrote:
> 
> It’s not really a complex shift register. All you really need is a set of Exclusive OR gates and a simple shift register of the desired length. If you can’t find a shift register that is long enough for your needs, you can simply cascade shorter shift registers. The only disadvantage of a discrete logic design is size. You can certainly tweak the taps if you have the shift registers and XOR gates as separate components.
> 
> Note that Texas Instruments lists their CD4006 product as Active.
> 
> http://www.ti.com/product/CD4006B-MIL
> 
> Of course, this can be simulated in software, but that seems like serious overkill given how simple the basic gates are. I enjoy using processors for processing, but it’s way more fun to use discrete logic gates for pure logic functions.
> 
> No matter which option you choose, I think that the signal conditioning from raw digital to analog would be a critical part of the design considerations.
> 
> Brian
> 
> 
>> On Nov 10, 2019, at 6:41 AM, bbob <fluxmonk at gmail.com> wrote:
>> anybody know of a digital noise circuit (similar to th ETI/Ken Stone design, http://www.synthpanel.com/modules/cgs31v10_digital_noise.html) that does not use the out-of-production CD4006?  Seems like you should be able to cobble together a complex shift register like that out of other still-available chips, but i'm not savvy enough on digital logic to do it myself.
>> 
>> b
> 
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