[sdiy] SMT transistor for white noise?

[Jonatan Liljedahl]

A 32-bit maximum length LFSR gives a sequence of 2**32-1, which at a sample
rate of 44.1kHz repeats after 27 hours! :)

/Jonatan
http://kymatica.com


sön 14 dec. 2025 kl. 01:53 skrev Jay Schwichtenberg via Synth-diy <
synth-diy at synth-diy.org>:

> I've used the EDN noise circuit at least 3 times and it has worked just
> fine. I always socket the noise transistor and select it. I bought a bag
> of 500 2N3904 transistors (for 1 cent each) about 15 years ago.
>
> Thing about LFSRs is they are usually pseudo random. They typically
> contain small sections of noise that repetitive. In most case that is
> good enough but not truly random. In order to get truly random noise
> digitally it can be somewhat complicated.
>
> Jay S.
>
> On 12/13/2025 1:05 PM, Mike Beauchamp wrote:
> > On 2025-12-13 09:35, Brother Theo via Synth-diy wrote:
> >> I switched to the 2 transistor noise circuit and have had zero issues
> >> since. The Future Retro 777 re-release uses that circuit.
> >
> > Hi Timothy, doing some duckduckgo-ing, I found a few...
> >
> > https://www.edn.com/simple-white-noise-generator/
> >
> >
> https://www.nutsvolts.com/magazine/article/bipolar_transistor_cookbook_part_5
> > (figure 20)
> >
> >
> > The EDN article is interesting. Seems like the second transistor is
> > just the amplification stage and the increased noise level is because
> > of the addition of C1. I don't understand the function of C1.. time to
> > get out the breadboard.
> >
> > Mike
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