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<DIV dir=ltr align=left><SPAN class=089292502-28012018><FONT color=#0000ff
size=2 face=Arial>Yes, you simply cannot use 5532 in filters. We learned
that the hard way. Their input currents are just too large -- so large, in
fact, that the opamp "golden rules" really don't apply to
them.</FONT></SPAN></DIV><BR>
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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>Guy
McCusker<BR><B>Sent:</B> Saturday, January 27, 2018 9:02 AM<BR><B>To:</B> Tim
Ressel<BR><B>Cc:</B> SYNTH DIY<BR><B>Subject:</B> Re: [sdiy] Filter
problems<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV>
<DIV dir=auto>Are you really using 5532s there? Does it behave the same way
with a FET op amp (e.g. TL07x or similar) instead? I would have thought the
input bias current of a 5532 made it unsuitable for use as an integrator at
all, and especially with a device like a 2164 which I understand is fussy
about its current output. </DIV>
<DIV dir=auto><BR></DIV>
<DIV dir=auto>Guessing really...</DIV><BR>
<DIV class=gmail_quote>
<DIV>On Sat, 27 Jan 2018 at 16:30, Tim Ressel <<A
href="mailto:timr@circuitabbey.com">timr@circuitabbey.com</A>>
wrote:<BR></DIV>
<BLOCKQUOTE
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class=gmail_quote>Hi,<BR><BR>Filters can be a pain. I've got one that is
misbehaving. Here is a link<BR>to the schematic:<BR><BR><A
href="https://www.dropbox.com/s/acjvwb17nmuok1n/PrismFilter.pdf?dl=0"
rel=noreferrer
target=_blank>https://www.dropbox.com/s/acjvwb17nmuok1n/PrismFilter.pdf?dl=0</A><BR><BR>At
low CVs it filters fine, but as the freq cv hits around 2 volts
the<BR>behavior gets odd. I start seeing a rising DC bias on all the
outputs.<BR>At about 3 volts all the outputs rail positive.<BR><BR>Any help
is appreciated. Thanks for playing!<BR><BR>--<BR>--Tim Ressel<BR>Circuit
Abbey<BR><A href="mailto:timr@circuitabbey.com"
target=_blank>timr@circuitabbey.com</A><BR><BR>_______________________________________________<BR>Synth-diy
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