[sdiy] Mind blown -- TL074 saturated outputs different

[Richie Burnett]

These days I think you'd just use a cheap microcontroller with built-in ADC? 

-Richie, 

Sent from my Xperia SP on O2

---- jschwich53 at comcast.net wrote ----

>Could you use something like a LM3914 for this?
>
>
>Sent from Xfinity Connect Application
>
>-----Original Message-----
>
>From: dixon at mail.ubc.ca
>To: igg.debus at gmail.com, synth-diy at synth-diy.org
>Sent: 2018-11-28 12:51:44 PM 
>Subject: Re: [sdiy] Mind blown -- TL074 saturated outputs different
>
>> > I need three of these
>> > comparators, and their sole function is to act as a 3-bit AD to 
>> > control some digital switches.
>> 
>> But why do you need precise output voltages from the comparators then?
>> 
>> And if you need quad comparators, why not use the good old 
>> LM339 instead of abusing a TL074 for that purpose?
>
>What I want to do is easier (in principle) with an opamp that swings
>positive and negative.  I'm using the output state of the comparators to
>provide the threshold voltages to the next comparator in the chain.  In this
>way, I can get a reasonably precise 3-bit AD converter.  My input CV is -5V
>to +5V, and the AD switches state every 1.25V (-3.75V, -2.50V, -1.25V,
>0.00V, +1.25V, +2.50V, +3.75V).  The 2-bit version I used in my 5-channel
>scanner worked perfectly with just divided raw opamp output, but the 3-bit
>version for my 9-channel scanner is a bit more finicky because the levels
>need to be just a bit more precise.
>
>However, I will get it working this afternoon.
>
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