In the synthesizer world there is a standard called "1V/octave" which basically refers to a linear input voltage corresponding to a logarithmic change in frequency (e.g. 1V = 100Hz, 2V = 200Hz, 3V = 400Hz, 4V = 800Hz and so on).
All the schematics that I can find are made for symmetric power supply and they only work with positive voltages. Now when I convert those schematics to my single supply environment I can only use voltages between 4.5V and 9.0V (I run on a +9VDC power supply). I have spent days modifying these circuits to my need but I don't have any luck.
Here's one of the many circuits provided by the internet: