Need help for calculation of this capacitive power supply
Calculate the capacitive reactancelike in the previous comment, then you will get your Average current thats available .Allow something for the Zener AND allow for low mains.You can neglect the output volts and R1 the surge limiting resistor for your rough calc .Remember that analog parts like caps have tolerances so there is only acedemic purpose in doing a calc better than 5% .If you are close to 50mA per microfarad then you are OK. NOW R1 must be fitted to protect C2 and BR1 and R3 can be Zero if you get your surge limit OK .If you are running a 1 watt thruhole Zener and a 470microfarad phillips 037 series cap then 100 ohm is fine . Be VERY careful of thev surge power rating of R1 .I have seen a few Christchurch Design Engineers muck these up with resistors failing open circuit .Some resistor manufacturers like melf are good at stating surge ratings .If you have bought your resistors off a strange man then play safe by using a higher value .Dont go too low in R1 even if your parts can hack it because these days the mains volts has more harmonics than yesteryear.