[sdiy] VCO comparator's reference voltage - rail OK?

Neil Harper metadata at gmx.com
Mon Mar 29 00:00:06 CEST 2021



On 3/28/21 5:47 PM, cheater cheater via Synth-diy wrote:
> On Sun, Mar 28, 2021 at 10:50 PM Neil Harper via Synth-diy
> <synth-diy at synth-diy.org> wrote:
>>
>> i have a drawer full of LM431's so i'll use that unless there's a reason
>> not to?
>
> You don't want an adjustable voltage reference, you want a precision
> constant voltage reference. Your adjustable voltage ref will be only
> as good as the resistors you have. So unless you have 0.01%
> resistors*, in the exact specific values that you need to get the
> voltage you need, you're out of luck.
>
> *needed for 1 cent frequency accuracy

i appreciate the reply cheater, but in this case the lm431 is just
setting the trip points of the comparator and have no need for .01%
accuracy here - just stability with unstable rail voltages.


--
/// Neil Harper
/// Every Wave is New Until it Breaks



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