Circuit for 12 v dc from 220 v ac without transformer?

First you should rectify the input ac voltage, but instead of using diode bridge, use a thyristor bridge(in diode bridge change the diodes to thyristor).

Connect the gates of the thristors together, cause they all must have the same fire angle.

On a paper calculate the dc level of the full wave signal(dc level of a full wave rectifier with thyristor is ready on your notebook or can find it on the internet by a simple search) to find the fire angle of the thyristors.

Now you can change the fire angle of the thyristors by changing the currents of the gates to get your desired dc level.

now you have a signal with your desired dc level, then smooth the output by a capacitor.