[sdiy] SMT transistor for white noise?

[Mike Bryant]

Too true 🙂   A large percentage of the world's small signal transistors now come from a huge fab in Chongqing and they just brand them to whatever their client wants.

Small power devices may be your best bet for more consistent noise as they are larger area and so will have a few more defects in them.
________________________________
From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Gordonjcp <gordonjcp at gjcp.net>
Sent: 13 December 2025 10:32
To: synth-diy at synth-diy.org <synth-diy at synth-diy.org>
Subject: Re: [sdiy] SMT transistor for white noise?

On Sat, Dec 13, 2025 at 12:55:30AM -0500, Mike Beauchamp wrote:
> I'm noticing my latest batch of MMBT3904 by ONSEMI are barely creating any
> white noise, requiring about 8000x gain to get up to +/- 5V.
>
> Previous batches of the MMBT3904 only required about 500x gain to get up to
> +/- 5V. When I was using TH 2N3904, I think the gain required was only about
> 200x.

I'm guessing you've got cheap Chinese ones this time round. They're far too high quality to use as noise sources.

You need to pay a bit extra to get American-made dodgy counterfeit components for this.

--
Gordonjcp
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