<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Don’t you mean <a href="https://patents.google.com/patent/US4514704A/en?inventor=Douglas+R.+Curtis" class="">https://patents.google.com/patent/US4514704A/en?inventor=Douglas+R.+Curtis</a> ?<div class=""><br class=""></div><div class="">I only say that because this is a filter and the one you posted is a “linear/logarithmic analog multiplier”</div><div class="">Anyway, cool stuff.</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">Mark</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Nov 2, 2023, at 1:07 PM, René Schmitz <<a href="mailto:synth@schmitzbits.de" class="">synth@schmitzbits.de</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" class="">
<div class="">
<div class="moz-cite-prefix">On 02.11.2023 11:15, Andrew Simper via
Synth-diy wrote:<br class="">
</div>
<blockquote type="cite" cite="mid:CAAxOnzZG_ZQOsJZL6nKDXij3+GE9GHq28PF1dGoJ06bg64pmzw@mail.gmail.com" class="">
<meta http-equiv="content-type" content="text/html; charset=UTF-8" class="">
<div dir="ltr" class="">I've already done detailed modelling on the SSM2040
and posted a video to youtube on this model being matched to the
LA67 Maca filter that uses the SSI2140.
<div class=""><br class="">
</div>
<div class="">Can you please post links to the internals of the CEM3320?</div>
</div>
</blockquote><p class=""><a class="moz-txt-link-freetext" href="https://patents.google.com/patent/US4004141A/en">https://patents.google.com/patent/US4004141A/en</a></p><p class="">Its different from the 2040 in so far that it has logarithmic
shaping before an OTA. ("linearising diodes")<br class="">
</p><p class="">The OTA core is very similar to the arrangement in the 2040. But
the control and audio inputs are realized differently. <br class="">
</p><p class="">I've been pondering about this: How can this be patentable, if
this is so similar in its working principle, and all the parts had
been used elsewhere.<br class="">
</p><p class=""><br class="">
</p><p class="">Best,</p><p class=""> René<br class="">
</p><p class=""><br class="">
</p>
<blockquote type="cite" cite="mid:CAAxOnzZG_ZQOsJZL6nKDXij3+GE9GHq28PF1dGoJ06bg64pmzw@mail.gmail.com" class="">
<div dir="ltr" class="">
<div class=""><br class="">
</div>
<div class="">Cheers,</div>
<div class=""><br class="">
</div>
<div class="">Andy</div>
</div>
<br class="">
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Thu, 2 Nov 2023 at 16:44,
Neil Johnson <<a href="mailto:neil.johnson71@gmail.com" moz-do-not-send="true" class="moz-txt-link-freetext">neil.johnson71@gmail.com</a>>
wrote:<br class="">
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">Hi,<br class="">
<br class="">
Andrew Simper wrote:<br class="">
><br class="">
> And a few patents referenced in the articles:<br class="">
><br class="">
> Embley:<br class="">
> <a href="https://patents.google.com/patent/US3532868A/en" rel="noreferrer" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://patents.google.com/patent/US3532868A/en</a><br class="">
><br class="">
> Buff:<br class="">
> <a href="https://patents.google.com/patent/US4341962A/en" rel="noreferrer" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://patents.google.com/patent/US4341962A/en</a><br class="">
><br class="">
> Blackmer:<br class="">
> <a href="https://patents.google.com/patent/US3714462A/en" rel="noreferrer" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://patents.google.com/patent/US3714462A/en</a><br class="">
> <a href="https://patents.google.com/patent/US4403199A/en" rel="noreferrer" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://patents.google.com/patent/US4403199A/en</a><br class="">
<br class="">
If you're hunting for patents to understand the SSM2040 then
you could<br class="">
start with the original patent:<br class="">
<a href="https://patents.google.com/patent/US3969682A/en" rel="noreferrer" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://patents.google.com/patent/US3969682A/en</a><br class="">
<br class="">
For fans of the SSM2044:<br class="">
<a href="https://patents.google.com/patent/US4404529A/en" rel="noreferrer" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://patents.google.com/patent/US4404529A/en</a><br class="">
<br class="">
Neil<br class="">
</blockquote>
</div>
<br class="">
<fieldset class="moz-mime-attachment-header"></fieldset>
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