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<p>The good new is with through hole you can try different amps to
see which one does the trick.</p>
<p>--Timbo<br>
</p>
<br>
<div class="moz-cite-prefix">On 8/15/2018 10:37 AM, David G Dixon
wrote:<br>
</div>
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cite="mid:2445B289B3BA48128D23C5FE2C76409F@galvanox01">
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<div dir="ltr" align="left"><span class="248123117-15082018"><font
size="2" face="Arial" color="#0000ff">Thanks for the great
response, Roman.</font></span></div>
<div dir="ltr" align="left"><span class="248123117-15082018"></span>�</div>
<div dir="ltr" align="left"><span class="248123117-15082018"><font
size="2" face="Arial" color="#0000ff">Possibly stupid
follow-up question:� </font></span></div>
<div dir="ltr" align="left"><span class="248123117-15082018"></span>�</div>
<div dir="ltr" align="left"><span class="248123117-15082018"><font
size="2" face="Arial" color="#0000ff">Why would ESD have an
effect on a JFET-input opamp?� I thought that only CMOS was
susceptible to ESD, because of the oxide gate insulator, but
not JFET.� The LF444 should be no more susceptible to
handling issues than TL074.� The handling would have to have
been unbelievably abusive to damage the chips, I would have
thought.</font></span></div>
<div><span class="248123117-15082018"></span>�</div>
<div><span class="248123117-15082018"><font size="2" face="Arial"
color="#0000ff">If I'm wrong about this, please disabuse me!</font></span></div>
<div dir="ltr" align="left"><br>
</div>
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<div dir="ltr" class="OutlookMessageHeader" align="left"
lang="en-us">
<hr tabindex="-1"> <font size="2" face="Tahoma"><b>From:</b>
Roman [<a class="moz-txt-link-freetext" href="mailto:modular@go2.pl">mailto:modular@go2.pl</a>] <br>
<b>Sent:</b> Wednesday, August 15, 2018 9:10 AM<br>
<b>To:</b> David G Dixon; <a class="moz-txt-link-abbreviated" href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</a><br>
<b>Subject:</b> Odp: [sdiy] low input bias current opamps<br>
</font><br>
</div>
<div>The answer to A) is no, because of 1)<br>
</div>
<div>Recently I made some THT design and was just so happy about
it until I found how many parts that I freely use in SMD are
simply not made in THT, so the choice usually comes to one
part if any.<br>
</div>
<div><br>
</div>
<div>The answer to B) is usually Mouser, but they have sometimes
errors in describing parameters, or take different values to
the table, like "typical" for one part and "minimum" for the
other part. Sometimes I use DigiKey, mostly because they seem
to have more refined parameters to search and I can type the
quantity of interest, and then sort by the price. Mouser sorts
only at qty 1 which is useless.<br>
</div>
<div>And obviously all manufacturer's websites contain
parametric search, which is the most accuratre, but still I
prefer Mouser because it gives me guidance of the price and
availability.<br>
</div>
<div><br>
</div>
<div>And if it's for some S&H, why don't you stick with
TL0xx? Are you sure your switching key has lower leakage than
bias of TL0xx opamp? Or try LF347 maybe but it's inferior to
LF444 in this application anyway.<br>
</div>
<div><br>
</div>
<div>Give LF444 a chance, get new ones, maybe they were handled
very badly and inputs were damaged by ESD because of bad
storage. They would still work but bias may be in range of nA
instead of pA.<br>
</div>
<div><br>
</div>
<div>Roman<br>
</div>
<div class="nh_extra">
<p>Dnia 15 sierpnia 2018 05:48 David G Dixon
<a class="moz-txt-link-rfc2396E" href="mailto:dixon@mail.ubc.ca"><dixon@mail.ubc.ca></a> napisa�(a):<br>
</p>
<blockquote style="BORDER-LEFT: #999 2px solid; MARGIN: 0px;
PADDING-LEFT: 8px" class="nh_quote">
<div id="gwp3c8fd2db">
<div>Hey Team,<br>
</div>
<div><br>
</div>
<div>I'm looking for opamps with the following properties:<br>
</div>
<div><br>
</div>
<div>1) Through-hole<br>
</div>
<div>2) Quad opamp<br>
</div>
<div>3) 14-DIP package<br>
</div>
<div>4) High power range (+/-18V, say)<br>
</div>
<div>5) Low input bias current (10 pA or less typical)<br>
</div>
<div>6) Pin-compatible with TL074, etc.<br>
</div>
<div>7) Not LF444 (cuz they all seem to be defective)<br>
</div>
<div><br>
</div>
<div>So, basically, I'm looking for a suitable alternative
for LF444.<br>
</div>
<div><br>
</div>
<div>So, here are my questions:<br>
</div>
<div><br>
</div>
<div>A) Do you know of such a thing<br>
</div>
<div>B) How does one go about finding such a thing,
generally?<br>
</div>
<div><br>
</div>
<div>Thanks in advance!<br>
</div>
<div>Dave (Floating VCA) Dixon<br>
</div>
<div><br>
</div>
<div>_______________________________________________<br>
</div>
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<div><br>
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<br>
<pre class="moz-signature" cols="72">--
--Tim Ressel
Circuit Abbey
<a class="moz-txt-link-abbreviated" href="mailto:timr@circuitabbey.com">timr@circuitabbey.com</a></pre>
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