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

[Pete Hartman]

What's wrong with the cheaper LM4040's?

e.g.
https://www.mouser.com/ProductDetail/Diodes-Incorporated/LM4040B25FTA?qs=GWgl%252BsiMZr%2F%252BaZ%252BmKrTIBg%3D%3D

On Sun, Mar 28, 2021 at 3:09 PM cheater cheater <cheater00social at gmail.com>
wrote:

> You want a REF03 voltage reference from AD. That's the easiest and
> best way of doing this.
>
> On Sun, Mar 28, 2021 at 9:42 PM Neil Harper <metadata at gmx.com> wrote:
> >
> > so now that I have my own little VCO going on the breadboard, i want to
> > do a perfboard module with it for my system. so now I'm thinking about
> > how this VCO will remain stable in a system where the rails might be
> > fluctuating.
> >
> > the first issue i see is that my LM311 comparator takes a reference
> > voltage drawn from my +15V rail through a resistor to set the trip
> > point. if that +15V waivers, so will my trip point.. and so will my
> > frequency. so should things like that be derived from an onboard
> > reference instead? is this common practice?
> >
> > I see in schematics like the ENS-76 VCO (
> > http://www.synthsource.com/ens76/vcofig6.jpg ) that the comparator
> > reference is just taken from the rail (through R13, R14 divider). Same
> > with Thomas Henry's VCO-1's, lots of references right off the rails.
> >
> >
> >
> >
> > --
> > /// Neil Harper
> > /// Every Wave is New Until it Breaks
> >
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