[sdiy] exponential converter details

[Nick Liebrecht]

Hi all,

I am having some trouble thinking through the typical expo converter
circuit.  The circuit i'm referring to is posted here.  

http://darkwing.uoregon.edu/~nick/Expo.pdf

It's taken from Barry Klein's book.I understand the CV ranging/scaling
part, but the actual current part is confusing me.  I recognize the
actual current source built around the op amp, but I'm fuzzy about
what all the parts do, especially the capacitor.  

Can anyone explain this circuit to me?  I want to learn why the
certain part values were chosen, and with what equations.

Thanks in advance,
Nick Liebrecht



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