I have this AC 20V to DC 5V converter with zener diode circuit. It works as expected if there is no load connected. As soon as I connect the load, in this case LED diode with 20mA consumption, the 5V output is reduced to 1.9V only and LED lights only with low light. I tried to calculate various R1 values from 120Ohm to 3K, but i never can reach output voltage higher then 2.2V. I also tried to reduce and even remove R2, but there was no significant change. Without load output gives 5.1V. Zener current is calculated for 20mA without load.
Can someone point me what can be the problem?
20V AC source is 10Amps strong source, so it can be excluded as source of the problem.