frequency tracking

[Ethan Robert Duni]

hello

i am looking for a good way to build a frequency follower.  all i need from
it is a CV output.  what i am thinking of doing would be running the input
signal accross a simple RC filter and then tapping the voltage off of one of
the components (depending on whether i wanted inverse or direct scaling;
haven't decided yet.. maybe both), and then buffering and rectifying it.
would this work, or are there more complex considerations i'm unaware of?  

this isn't for any particular project (yet), just a point of interest for me..

thanks
Ethan Duni
http://ieng9.ucsd.edu/~ee20waf/file.html