This circuit will supply up to about 20ma at 12 volts. It uses capacitive reactance instead of resistance; and it doesn't generate very much heat.The circuit draws about 30ma AC.If you need more current, use a larger value capacitor; or put two in parallel; but be careful of what you are doing to the Watts.
The low voltage 'AC' is supplied by D1 and D8.Also you can replace R3 and D3 with a 78 Series regulator.
u1, 100ma fuse
R1, 100 ohm , 0.25watt
R2, 1K ohm, 2 watt
R3, 1k ohm , 0.25watt
C1, 470nF, 400v, polyseter
D4-D7, 1N4001 or 1N4007
D1, D8, 16v Zener Diode
C2, 1uF electrolyte
D2, 12v Zener Diode