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<DIV dir=ltr align=left><SPAN class=322542018-26042018><FONT color=#0000ff
size=2 face=Arial>Hey Oren,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=322542018-26042018><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=322542018-26042018><FONT color=#0000ff
size=2 face=Arial>The typical IBC for CA3140 is 10pA, which is the same as LF444
(presuming they actually work). LF444 is cheap as chips and is a
"standard pinout" quad. Hence, I'd stick with it (presuming I could
actually get some that weren't garbage).</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=322542018-26042018><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=322542018-26042018><FONT color=#0000ff
size=2 face=Arial>The CA3130 is twice as good, with typical IBC of 5 pA.
However, again, it is only a single opamp. I need a quad (I'm not going to
completely redo the layout).</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=322542018-26042018><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=322542018-26042018><FONT color=#0000ff
size=2 face=Arial>Any good quads (better than LF444)?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=322542018-26042018></SPAN> </DIV>
<DIV dir=ltr align=left>
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<FONT size=2 face=Tahoma><B>From:</B> Synth-diy
[mailto:synth-diy-bounces@synth-diy.org] <B>On Behalf Of </B>Oren
Leavitt<BR><B>Sent:</B> Thursday, April 26, 2018 10:02 AM<BR><B>To:</B>
synth-diy@synth-diy.org<BR><B>Subject:</B> Re: [sdiy] Happenin' new
opamp<BR></FONT><BR></DIV>
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style="BORDER-LEFT: #0000ff 2px solid; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV></DIV>
<P>Not bad! I happen to have a few tubes of TL06x sitting around - a use for
'em!</P>
<P>CA3140/3130 are still today some of the best for S&H circuits with just
a few pA of input current<BR></P>
<P>- Oren<BR></P><BR>
<DIV class=moz-cite-prefix>On 4/26/18 11:42 AM, David G Dixon wrote:<BR></DIV>
<BLOCKQUOTE cite=mid:6FC3CF2E745C4488B29EC1209B52F016@galvanox01
type="cite"><META name=GENERATOR content="MSHTML 8.00.6001.23588">
<DIV dir=ltr align=left><SPAN class=803582516-26042018><FONT color=#0000ff
size=2 face=Arial>Agreed, and agreed.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=803582516-26042018></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=803582516-26042018><FONT color=#0000ff
size=2 face=Arial>I have made a (somewhat well known) version of the CGS
analog shift register for quite a few people, with a number of improvements
over the original. I had traditionally used LF444 for the S&H
buffers because of its low input bias current (typically 10 pA).
However, recently, I bought a number of them from a local shop (they had
been sourced from Digikey), and they turned out to be defective (or
counterfeit -- I'm not sure, they just don't work). Out of
desperation, I ended up using a TL064 instead (typical IBC 30 pA, compared
to 65 pA for TL074) because that was the next best thing I had in my stores,
and it worked like a dream. Very little S&H drift, even in "loop"
mode (where the same three stored voltages are looped around the ASR outputs
over and over). I use 0.1uF caps in these S&H circuits, so 30 pA
generates very little drift (about 300 uV/s, which I guess I can live
with).</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=803582516-26042018></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=803582516-26042018><FONT color=#0000ff
size=2 face=Arial>So now, TL064 is my standard opamp for those
buffers. Maybe one of these days I'll look for a relatively
inexpensive quad with really low IBC (1 pA or less) -- anybody have any
suggestions?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=803582516-26042018></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=803582516-26042018></SPAN> </DIV>
<DIV dir=ltr align=left>
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</DIV>
<DIV dir=ltr align=left><FONT size=2 face=Tahoma><B>From:</B> Synth-diy [<A
class=moz-txt-link-freetext
href="mailto:synth-diy-bounces@synth-diy.org">mailto:synth-diy-bounces@synth-diy.org</A>]
<B>On Behalf Of </B>Mattias Rickardsson<BR><B>Sent:</B> Thursday, April 26,
2018 2:54 AM<BR><B>To:</B> Michael E Caloroso<BR><B>Cc:</B> SDIY
List<BR><B>Subject:</B> Re: [sdiy] Happenin' new opamp<BR></FONT><BR></DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #0000ff 2px solid; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px"
dir=ltr>
<DIV dir=ltr>
<DIV class=gmail_extra>
<DIV class=gmail_quote>On 25 April 2018 at 06:15, Michael E Caloroso <SPAN
dir=ltr><<A href="mailto:mec.forumreader@gmail.com" target=_blank
moz-do-not-send="true">mec.forumreader@gmail.com</A>></SPAN> wrote:<BR>
<BLOCKQUOTE
style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex"
class=gmail_quote>The input offsets - hence CV error and drift - are
temperature<BR>dependent. A substrate quad is going to generate
more heat than a<BR>single or dual.<BR><BR>There's a reason you see
single opamps on the input stages of VCOs.<BR></BLOCKQUOTE>
<DIV><BR></DIV>
<DIV>Ah, thanks for pointing that out.</DIV>
<DIV><BR></DIV>
<DIV>Speaking of CV and favourite op-amps, I prefer using TL064 for CV
multiplexing. They are quad, but <SPAN
style="TEXT-TRANSFORM: none; BACKGROUND-COLOR: rgb(255,255,255); FONT-STYLE: normal; TEXT-INDENT: 0px; DISPLAY: inline; FONT-FAMILY: arial,sans-serif; WHITE-SPACE: normal; FLOAT: none; LETTER-SPACING: normal; COLOR: rgb(34,34,34); FONT-SIZE: small; FONT-WEIGHT: 400; WORD-SPACING: 0px; font-variant-ligatures: normal; font-variant-caps: normal; text-decoration-style: initial; text-decoration-color: initial">low-power</SPAN> -
so they keep cool.</DIV>
<DIV><BR></DIV>
<DIV>When I come to think of it... I also very much prefer quads due to
them having the outputs on the corner pins. Very easy to probe and measure
on. It's a pity that the dual op-amps got the pinout they got, with an
output on pin 7. :-)</DIV>
<DIV><BR></DIV>
<DIV>/mr</DIV>
<DIV><BR></DIV></DIV></DIV></DIV></BLOCKQUOTE><BR>
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