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<div class="moz-cite-prefix">On 20.06.2025 23:15, david walker via
Synth-diy wrote:<br>
</div>
<blockquote type="cite"
cite="mid:1719148185.1465325.1750454148874@mail.yahoo.com">
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<div dir="ltr" data-setdir="false">hello taking about JFET,s can
any point out any were on line that show you how to use JFET,s
in oscillator circuits ? <br>
</div>
</div>
</blockquote>
<p><br>
</p>
<p>A prominent example is the SEM1a from Oberheim:</p>
<p><br>
</p>
<p>JFET as high-Z buffer in the VCO <br>
</p>
<p><a class="moz-txt-link-freetext" href="https://synthfool.com/docs/Oberheim/Oberheim_SEM1A/Oberheim_SEM_1A_Schematics.pdf">https://synthfool.com/docs/Oberheim/Oberheim_SEM1A/Oberheim_SEM_1A_Schematics.pdf</a></p>
<p>Two JFETs (Q2/Q3) are used in a source follower configuration to
buffer the main integration cap with high impedance. <br>
</p>
<p>Today we would probably find a jfet opamp instead.</p>
<p>(JFETs are also used in the SEM filter.)<br>
</p>
<p><br>
</p>
<p>Another example:</p>
<p>JFETs as discharge switch</p>
<p><a class="moz-txt-link-freetext" href="https://schmitzbits.de/vco3.html">https://schmitzbits.de/vco3.html</a></p>
<p>This one used two FETs, but they don't need to be matched. And
you can do this with a single FET as well.<br>
</p>
<p><br>
</p>
<p>I've only used once a dual JFET where good matching was required
(in fact this was a 2SK389), but this circuit was never published.
<br>
</p>
<p><br>
</p>
<p>FETs have large unit to unit variations, good for one-off
hobbyist or space mission work, but </p>
<p>annoying to show-stopper for mass production. So you'll not see
them that often in the wild. <br>
</p>
<p><br>
</p>
<p>Cheers,</p>
<p> René<br>
</p>
<p><br>
</p>
<p><br>
</p>
<p><br>
</p>
<blockquote type="cite"
cite="mid:1719148185.1465325.1750454148874@mail.yahoo.com">
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style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:13px;">
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<div> On Friday 20 June 2025 at 21:58:12 BST, Mike Bryant
<a class="moz-txt-link-rfc2396E" href="mailto:mbryant@futurehorizons.com"><mbryant@futurehorizons.com></a> wrote: </div>
<div><br>
</div>
<div><br>
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<div>
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<div
style="font-family:Aptos, Calibri, Helvetica, sans-serif;font-size:12pt;color:rgb(0, 0, 0);"
class="yiv6462849909elementToProof">
LSK389 is hardly new. Been around for a long time,
although availability varies.</div>
<div
style="font-family:Aptos, Calibri, Helvetica, sans-serif;font-size:12pt;color:rgb(0, 0, 0);"
class="yiv6462849909elementToProof">
But the price never seems to vary. </div>
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style="font-family:Aptos, Calibri, Helvetica, sans-serif;font-size:12pt;color:rgb(0, 0, 0);">
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<hr style="display:inline-block;width:98%;">
<div id="yiv6462849909yqt21681"
class="yiv6462849909yqt2765363805">
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<div
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<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 Tim Parkhurst via Synth-diy
<a class="moz-txt-link-rfc2396E" href="mailto:synth-diy@synth-diy.org"><synth-diy@synth-diy.org></a><br clear="none">
<b>Sent:</b> 20 June 2025 21:34<br clear="none">
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</a> DIY
<a class="moz-txt-link-rfc2396E" href="mailto:synth-diy@synth-diy.org"><synth-diy@synth-diy.org></a><br clear="none">
<b>Subject:</b> [sdiy] Dual Matched N JFET from
Linear</div>
<div style="direction:ltr;"> </div>
</div>
<div style="direction:ltr;">Hey, Analog Hounds, </div>
<div style="direction:ltr;"><br clear="none">
</div>
<div style="direction:ltr;">Linear Systems is
promoting a new Matched Dual JFET, and you might
even be able to get a sample or two. Useful? Not? </div>
<div style="direction:ltr;"><br clear="none">
</div>
<div style="direction:ltr;"><a
rel="nofollow noopener noreferrer" shape="rect"
id="yiv6462849909OWA85e0fa77-bd94-762d-ba62-8725d79bbc76"
target="_blank"
href="https://www.linearsystems.com/post/why-engineers-choose-the-lsk389-for-high-precision-analog-design?utm_campaign=d2b0395f-db24-487d-8e02-adcff714e7a8&utm_source=so&utm_medium=mail&cid=a05ef50a-a9c5-473d-950b-37f3f1a2d83d"
class="yiv6462849909OWAAutoLink"
moz-do-not-send="true">https://www.linearsystems.com/post/why-engineers-choose-the-lsk389-for-high-precision-analog-design?utm_campaign=d2b0395f-db24-487d-8e02-adcff714e7a8&utm_source=so&utm_medium=mail&cid=a05ef50a-a9c5-473d-950b-37f3f1a2d83d</a></div>
<div style="direction:ltr;"><br clear="none">
</div>
<div style="direction:ltr;">Tim (define "useful")
Servo<br clear="none">
---<br clear="none">
"Imagination is more important than knowledge." -
Albert Einstein<br clear="none">
<br clear="none">
<br clear="none">
<br clear="none">
</div>
</div>
<div
style="font-family:Aptos, Calibri, Helvetica, sans-serif;font-size:12pt;color:rgb(0, 0, 0);">
<br clear="none">
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<hr style="display:inline-block;width:98%;">
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<div
style="direction:ltr;font-family:Calibri, sans-serif;font-size:11pt;color:rgb(0, 0, 0);">
<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
Tim Parkhurst via Synth-diy
<a class="moz-txt-link-rfc2396E" href="mailto:synth-diy@synth-diy.org"><synth-diy@synth-diy.org></a><br clear="none">
<b>Sent:</b> 20 June 2025 21:34<br clear="none">
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</a> DIY
<a class="moz-txt-link-rfc2396E" href="mailto:synth-diy@synth-diy.org"><synth-diy@synth-diy.org></a><br clear="none">
<b>Subject:</b> [sdiy] Dual Matched N JFET from
Linear</div>
<div style="direction:ltr;"> </div>
</div>
<div style="direction:ltr;">Hey, Analog Hounds, </div>
<div style="direction:ltr;"><br clear="none">
</div>
<div style="direction:ltr;">Linear Systems is promoting
a new Matched Dual JFET, and you might even be able to
get a sample or two. Useful? Not? </div>
<div style="direction:ltr;"><br clear="none">
</div>
<div style="direction:ltr;"><a
rel="nofollow noopener noreferrer" shape="rect"
target="_blank"
href="https://www.linearsystems.com/post/why-engineers-choose-the-lsk389-for-high-precision-analog-design?utm_campaign=d2b0395f-db24-487d-8e02-adcff714e7a8&utm_source=so&utm_medium=mail&cid=a05ef50a-a9c5-473d-950b-37f3f1a2d83d"
moz-do-not-send="true">https://www.linearsystems.com/post/why-engineers-choose-the-lsk389-for-high-precision-analog-design?utm_campaign=d2b0395f-db24-487d-8e02-adcff714e7a8&utm_source=so&utm_medium=mail&cid=a05ef50a-a9c5-473d-950b-37f3f1a2d83d</a></div>
<div style="direction:ltr;"><br clear="none">
</div>
<div style="direction:ltr;">Tim (define "useful") Servo<br
clear="none">
---<br clear="none">
"Imagination is more important than knowledge." -
Albert Einstein<br clear="none">
<br clear="none">
<br clear="none">
<br clear="none">
</div>
</div>
</div>
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<pre class="moz-signature" cols="72">--
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