>Try this- http://www.synthfool.com/diy/vcs3filt.gif >-K Great !! One piece of info to add: The FET should have a threshold voltage between 2.5 and 3.5 V. And the strange "kpF" notation actually means "nF". (nano = kilo * pico (;->) ) BTW: look at this minimalsistic but very effective 3-transistor expo converter ! JH.