Vou ressuscitar o tópico, pois voltei agora as pesquisar sobre LFO.

Achei alguns artigos e esquemas legais nesses links

http://www.beavisaudio.com/Projects/CMOS_Synthesizers/

http://electro-music.com/forum/topic-31166.html

http://experimentalistsanonymous.com/diy/Schematics/Oscillators%20LFOs%20and%20Signal%20Generators/

http://www.beavisaudio.com/Projects/ColorsoundWah/