[sdiy] SMT transistor for white noise?

[Jay Schwichtenberg]

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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