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<p>Hi All,</p>
<p><br>
I'm reminded of "ChaosKey" a design that Keith Packard and Bdale
Garbee put together to create entropy for the random number
generator in the Linux kernel. It's based off a pair of
transistors biased up at something like 20V and fully open
source. <a class="moz-txt-link-freetext" href="https://altusmetrum.org/ChaosKey/">https://altusmetrum.org/ChaosKey/</a></p>
<p><br>
</p>
<p>Might be of interest?<br>
<br>
</p>
<p>Cheers,<br>
Hugh</p>
<p><br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 15/12/2025 07:38, Mike Bryant wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CWLP265MB7132BB62D7C982EE6D01F746DBACA@CWLP265MB7132.GBRP265.PROD.OUTLOOK.COM">
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style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
I think you'll find the LM194 and its clones are the only
monolithic ones left now. There were others a few years ago
but most others are now two very well matched but separate die
in the same package.</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif"
style="font-size:11pt" color="#000000"><b>From:</b> Synth-diy
<a class="moz-txt-link-rfc2396E" href="mailto:synth-diy-bounces@synth-diy.org"><synth-diy-bounces@synth-diy.org></a> on behalf of Ian Fritz
via Synth-diy <a class="moz-txt-link-rfc2396E" href="mailto:synth-diy@synth-diy.org"><synth-diy@synth-diy.org></a><br>
<b>Sent:</b> 13 December 2025 19:53<br>
<b>To:</b> Gordonjcp <a class="moz-txt-link-rfc2396E" href="mailto:gordonjcp@gjcp.net"><gordonjcp@gjcp.net></a><br>
<b>Cc:</b> <a class="moz-txt-link-abbreviated" href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</a>
<a class="moz-txt-link-rfc2396E" href="mailto:synth-diy@synth-diy.org"><synth-diy@synth-diy.org></a><br>
<b>Subject:</b> Re: [sdiy] SMT transistor for white noise?</font>
<div> </div>
</div>
<div class="BodyFragment"><font size="2"><span
style="font-size:11pt;">
<div class="PlainText">Do they have these in monolithic pair
packages?<br>
<br>
Ian<br>
<br>
> On Dec 13, 2025, at 12:27 PM, Gordonjcp
<a class="moz-txt-link-rfc2396E" href="mailto:gordonjcp@gjcp.net"><gordonjcp@gjcp.net></a> wrote:<br>
> <br>
> On Sat, Dec 13, 2025 at 11:11:54AM +0000, Mike
Bryant wrote:<br>
>> 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.<br>
>> <br>
> <br>
> Many years ago I bought a bag of something like 500
of the cheapest Chinesiest BC548-wannabes from Some Dude
In Shenzen On eBay, expecting to maybe hand-match a couple
of sets of a dozen reasonably close ones for filters.<br>
> <br>
> Nope.<br>
> <br>
> Any two you pulled out of the bag at random would
have the same Vbe down to *microvolts*.<br>
> <br>
> So that was a quicker evening than I anticipated.<br>
> <br>
> --<br>
> Gordonjcp<br>
> <br>
>
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<pre wrap="" class="moz-quote-pre">________________________________________________________
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</blockquote>
<pre class="moz-signature" cols="72">--
I am slowly moving to <a class="moz-txt-link-abbreviated" href="mailto:hugh@blemings.id.au">hugh@blemings.id.au</a> as my main email address.
If you're using <a class="moz-txt-link-abbreviated" href="mailto:hugh@blemings.org">hugh@blemings.org</a> please update your address book accordingly.
Thank you :)</pre>
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