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<p><span style="font-size:12.0pt;color:black">Here's an overkill solution but it gives you much flexibility: Get an MCU with an ADC and DAC and easily implement your rule in software.<o:p></o:p></span></p>
<p><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
<p><span style="font-size:12.0pt;color:black">JJS<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="color:black">From:</span></b><span style="color:black"> Synth-diy <synth-diy-bounces@synth-diy.org> on behalf of Lloyd Abbott <lloydabbott94@gmail.com><br>
<b>Sent:</b> Wednesday, June 20, 2018 8:30:30 AM<br>
<b>To:</b> Guy McCusker<br>
<b>Cc:</b> synth-diy@synth-diy org<br>
<b>Subject:</b> Re: [sdiy] In search of a reasonably precise comparator output</span>
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<p class="MsoNormal">What rails do you have available ? Have you considered a comparator IC (e.g. LM339) rather than using general purpose op-amps ?
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<p class="MsoNormal">If you have 0V, +5V and +15V rails, with an LM339 you can reference the comparator input side to the 0V and +15V rails and have the output side referenced to 0V and +5V. The datasheet has an example circuit using one pullup resistor and
one cap per comparator.<o:p></o:p></p>
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<p class="MsoNormal">On Wed, Jun 20, 2018 at 4:05 PM, Guy McCusker <<a href="mailto:guy.mccusker@gmail.com" target="_blank">guy.mccusker@gmail.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Hello,<br>
I am "designing" (i.e. cobbling together) a circuit in which I need a<br>
comparator whose output is fairly accurately 0V or 5V.<br>
<br>
I can think of many ways to do this. Some are very stable (at least on<br>
paper) but appallingly complicated, which is bad because I need at<br>
least 7 of these; some are very simple but rely on careful trimming<br>
of the saturation voltage of an op amp, which I would rather not do<br>
for reasons of reproducibility.<br>
<br>
It is 100% likely that someone on this list has a very simple and<br>
solid way to do this, so rather than reinvent the wheel I thought I'd<br>
ask... how would you do it?<br>
<br>
(What I really want, in fact, is to take an input voltage X and output<br>
X if X<=5, or X-5, if X>5.)<br>
<br>
Guy.<br>
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<a href="http://synth-diy.org/mailman/listinfo/synth-diy" target="_blank">http://synth-diy.org/mailman/listinfo/synth-diy</a><o:p></o:p></p>
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