> Lots of jacks - not sure what the difference is between the calibrated
> and uncalibrated inputs.
>
In the summing section of a typical VCO or synth module, you use 1% resistors. That is 1
part in 100 accuracy.
The input A/D is 10 bits or 1 part in 1024. So using any two 1% resistors, the input
reading could differ by 20 "counts" (one res at +1%, one res at -1%). The simplest way to
trim that precisely is with a trimpot.
We want an input that is 0 counts at 0 volts and exactly 1023 counts at 5.000 volts (with
0.00499 volts per count). We can convert that to floating point and actually calculate in
real world voltages. Since the ouput is calibrated, you can work in real world voltages also.
The non-trimpot input is close but not precise. Unless you match the resistors by hand to
0.1% or buy them matched for 80 cents apiece.