The problem with some divider circuits is they drop out of will not track the full vco range. This scheme works well. As you can tell from sample there is no drop out. I started with the square then added 1 oct down, then 2 oct down then cranked the vco freq up then down. The Wave 200K http://www.mindspring.com/~vco/cbook/pics/suboct.wav -tg