Technical specifications:

Output voltage: 12 V stabilized
Output current: max. 1,5 A

Schematic diagram:

Parts list:

C1, C2, C4, C5 - 10 nF, 50 V
C3 - 4700 uF, 35 V
C6 - 100 uF
D1-D5 - 1N5408 or 1N5060
IO1 - 7812
Tr1 - 20 W transformer, 15 V output voltage