<html>
<head>
<meta content="text/html; charset=windows-1252"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
Someone on the MW forum did recently do a very short run PCB -
before Christmas, I think - maybe there'll be more?<br>
Around here:
<a class="moz-txt-link-freetext" href="https://www.muffwiggler.com/forum/viewtopic.php?t=81990&start=250">https://www.muffwiggler.com/forum/viewtopic.php?t=81990&start=250</a><br>
<br>
I've never really looked much into transistor matching, but wondered
if the Peak Atlas testers may be any good?<br>
I recently got one of their Capacitor ESR testers and it is very
quick and convenient.<br>
The company had some reconditioned units (of various different
tester models) available via Ebay at considerably less than the
standard prices..<br>
[Had a quick check now, but couldn't find their particular
listing..]<br>
<br>
<br>
<div class="moz-cite-prefix">On 09/01/2016 20:52, Mattias
Rickardsson wrote:<br>
</div>
<blockquote
cite="mid:CAP92RBXcAezAiR8L+gaCEj3TT-mWmvYMeR5xmAKexW6g2Gvmww@mail.gmail.com"
type="cite">
<p dir="ltr">I have a spare set of matched transistors for the
TTSH supplied by Thonk, if somebody needs them. Contact me
privately if interested.</p>
<p dir="ltr">Speaking of transistor matchers, are there any DIY
PCBs for them? I'd love to not have to build a temporary one on
a prototype board next time. :-)</p>
<p dir="ltr">/mr</p>
<div class="gmail_quote">Den 9 jan. 2016 5:30 em skrev "matt
holland" <<a moz-do-not-send="true"
href="mailto:matt@mattholland.org">matt@mattholland.org</a>>:<br
type="attribution">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Hi All,
<div><br>
</div>
<div>I'm in the process of helping a buddy build a TTSH and
as a result am being thrust into the world of transistor
matching. I could just get on with it and breadboard one
of the handful of circuits out there but instead I've been
staring at the Moog circuit linked to here [1] and trying
to understand the theory behind it. The non DUT transistor
is a current soruce, with the op amp giving the ability to
set the current without having to bother biasing it with a
precise Vbe. The two resistors on the non-inverting input
bias the inverting input to -5V, which enforce a 98uA
(~100uA) emitter current through the 51k resistor through
the magic of negative feedback. </div>
<div><br>
</div>
<div>It doesn't seem like the current value is even
important at all so long as it stays the same from one DUT
bjt to the next (i.e. temp is same from one measurement to
the next for the tester as well as the DUT). Then we
measure the Vbe across the DUT which is sort of a proxy
for measuring Is (Vb = Vt*ln(Ic/Is) since it Is that
models all the physical parameters that vary from one bjt
to the next and is the temp dependent parameter that gets
cancelled out in the expo converter to the extent that
they're identical.</div>
<div><br>
</div>
<div>The bit that I'm still having trouble with is the 10k
resistor. It's there in the NPN tester but not in the PNP
tester. I've seen this described as a "flaw" in the PNP
tester but I'm not sure what it's doing int the NPN
tester. I threw together a spice sim that steps the value
of it from 0 to 10k with absolutely no meaningful change
in the measured Vbe.</div>
<div><br>
</div>
<div>Apologies if this has been covered before and
appreciate any help.</div>
<div><br>
</div>
<div>mh</div>
<div><br>
</div>
<div>[1] <a moz-do-not-send="true"
href="http://www.musicfromouterspace.com/analogsynth_new/TRANSISTORMATCHER/images/moogmatchersmall.gif"
target="_blank">http://www.musicfromouterspace.com/analogsynth_new/TRANSISTORMATCHER/images/moogmatchersmall.gif</a> </div>
<div><br>
</div>
<div><br>
</div>
</div>
<br>
_______________________________________________<br>
Synth-diy mailing list<br>
<a moz-do-not-send="true"
href="mailto:Synth-diy@dropmix.xs4all.nl">Synth-diy@dropmix.xs4all.nl</a><br>
<a moz-do-not-send="true"
href="http://dropmix.xs4all.nl/mailman/listinfo/synth-diy"
rel="noreferrer" target="_blank">http://dropmix.xs4all.nl/mailman/listinfo/synth-diy</a><br>
<br>
</blockquote>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Synth-diy mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Synth-diy@dropmix.xs4all.nl">Synth-diy@dropmix.xs4all.nl</a>
<a class="moz-txt-link-freetext" href="http://dropmix.xs4all.nl/mailman/listinfo/synth-diy">http://dropmix.xs4all.nl/mailman/listinfo/synth-diy</a>
</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
BugBrand LTD
UK company No. 07199808
VAT No. GB 988 2629 57
1 Ninetree Hill
BRISTOL BS1 3SB
United Kingdom
<a class="moz-txt-link-abbreviated" href="http://www.bugbrand.co.uk">www.bugbrand.co.uk</a></pre>
</body>
</html>