<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1">
<title></title>
</head>
<body text="#000000" bgcolor="#ffffff">
Hah! I should have figured it wasn't a new idea. Looking at the
features of theOMNI filter, yours is a lot fancier - like the voltage
controlled "morph" feature.<br>
I'll try inverting the BP feedback, thanks.<br>
<br>
Grant Richter wrote:<br>
<blockquote type="cite" cite="midBBA5E92A.3EA31%25grichter@asapnet.net">
<pre wrap="">Congratulations, you have reinvented the Wiard Omni-Filter!
You will be wanting to add another set of switches to invert the feedback
phase for bandpass mode.
And no doubt adding allpass (phase shifter) mode when you realize it's just
half the LP switches on with the HP switches, which puts a variable
resistance in parallel with the cap... (don't ground the cap for this mode
of course).
Robert Rich complained because it didn't sound MORE like a CEM3320...
</pre>
<blockquote type="cite">
<pre wrap="">Just what we need - another filter circuit. Anyway, I've always liked
the CEM3320 filter chips, which has 4 transconductance stages which can
yield any of the standard filter response (HP, LP, BP, and All Pass) in
4th order, depending on how you interconnect the stages. I hit on the
idea of using analog switches to do the interconnecting and build a
switchable (not simultaneous) multimode filter. I previously built one
with a CEM3320 that yielded BP and LP functions. The new circuit
contains no CEMs but is built with LM13700 OTA's and MAX413 analog switches.
The HP and LP functions work perfectly, just as I expected. The BP
however doesn't seem to respond to the resonance settings as well as it
should (and certainly not as well as the CEM3320 BP).
Maybe some of you geniuses can take a look a make suggestions (make
suggestions even if you don't consider yourself a genius!).
I've got to break down and build me another case. I've got a box full of
loose modules without a home.
<a class="moz-txt-link-freetext" href="http://home.comcast.net/~sbernardi/elec/og2/og3_4pmultimode.html">http://home.comcast.net/~sbernardi/elec/og2/og3_4pmultimode.html</a>
--
Scott Bernardi
<a class="moz-txt-link-abbreviated" href="mailto:sbernardi@comcast.net">sbernardi@comcast.net</a>
</pre>
</blockquote>
<pre wrap=""><!---->
</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Scott Bernardi
<a class="moz-txt-link-abbreviated" href="mailto:sbernardi@comcast.net">sbernardi@comcast.net</a></pre>
</body>
</html>