This is a simple handy 0-12V DC power supply circuit that can works to provide 0-12V DC 700 mA with an M-2155 transformer or 1.4A for an M-2156 transformer. It also use a power switch SPDT, means that the voltage can be set. For heat protection, heat sink is needed for the BD679 transistor. It is because it will be over tempered when works more than 200mA.
0v to 12 volt output:
– 700mA with M 2155
– 1.4amp with M 2156
– 1A with 16v AC 1.5 amp plug pack
source : www.talkingelectronics.com