From Sam Young Cap. data book: 470u 16V LXV esr = 0.12R. 2200u 16v LXV esr = 0.039R. Therefore esr for 4 x 470u = 0.12/4 = 0.03R, about 75% of the esr of a 2200u. They probably could not get the 2200 caps at the time. George -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads