[sdiy] cv and adc...

[Paul Maddox]

Bert,

> I’m doing a microcontroller project which involves a/d conversion of CV
> signals ... can anyone give me some idea of the circuitry I need between
>the CV input jacks and the a/d conversion pin of my microcontroller?

basically you should assume the person pluugin the jac in is a moron, and
its could have anything on.
Most modulars can have CVs that run +10v to -10V, as you micros ADC probably
has a max of +5 and a min of -0.6v You should put a 5V zener across the
input of the ADC and a 1K resistor in series..
To drive the 1K you'll also need a voltage divider of some kind and possibly
something to rescale the 0v point to be 2.5v (if you want to allow bipolar
signals) .
A fairly simple resistor divider/opamp outght to suffice, but dont forget to
include the 5v zener to be 100% safe!

Paul