Father Tom - I've just started playing with LT Spice - from the Linear Technologies Web site. It is intended to be used to design switching regulators (using their chips, of course :) but seems to work quite well with other things. The price is right. http://www.linear-tech.com/software They call it SwitchCAD Larry Larry Bradley Orleans (Ottawa), Ontario, CANADA -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads