Olin Let me clarify my position on the cap charge question. Neglecting pawer factor and efficiency the power source can deliver 12 watts. If 12 V is converted to 300 V, the original stated voltage, the maximum available current is limited to 40 mA. 300 V X 40 mA = 12 watts. The current, I = dQ/ dt. Q = CE so I = C dE/ dt and I dt = C dE. Integrating both sides, It = CE and t = CE/I The time t = 160uF X 300 V / .04 A = 1.2 Seconds. This time was confirmed on Ansoft's program "Serenade" and Electronic Workbench version 5.1 They show a dV/dt of 250 V/s. 1.2 S X 250 V/S = 300 V. Of course with lower duty cycle we may be able to use 80. mA and reduce the charge time to 0.6 seconds. Charlie W8AWS Midland Electronics Specialties -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads