Do you require a regulated output? If yes what is the current requirement? regulated 12 volts can also be derived from feeding a 12.6 volt zener diode with 15 volts and utilising the same to feed a transisitor which will boost up the current. As a drop of 0.6 volts results in the transistor, 12 volts regulated will be available. Cheers
Current is not important. I want to obtain 12V dc output. There is 220V 50 hz ac
input. And i can not use ic (like 7812) for regultaion as i said before.
Thanks for your help...
You may either use transformor or capacitor based power supply to drop the voltage to arround 15-18 volts and as you say the current is not important, you may use Resistor + zener diode combination to get 12 volts. Cheers
If isolation is important, just use the same circuit given by Hameed, with 0-15 coil, but connect the bridge rectifier with the secondary of the transformor, and use a resistor 100E 0.5 watt in between the + and the Zener diode as shown in the figure below.. Cheers