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

Neil Harper metadata at gmx.com
Sun Mar 28 21:39:09 CEST 2021


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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