Russell McMahon wrote: ++++++++++++++++++++++++++++++++++++++++++ ... SDC lends itself to amateur and low cost implementations (unlike some methods which are applicable only to advanced or high technology users.) A basic measurement system could be produced from scrap material and off the shelf parts for a few dollars. ... ++++++++++++++++++++++++++++++++++++++++++ If understand correctly there were related posts (Jun 2002): "[PIC]: PCB cannot carry double?" "Re: [PIC]: Variable cap A/K/A "PCB cannot carry double?"" Mike. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.