12 VOLTS DUAL VOLTAGE POWER SUPPLY CIRCUIT DIAGRAM PROJECT FREE INFORMATION

This is a basic circuit diagram of power supply that has dual voltage. The design is for 12 volts. 

Circuit Specs are as follows:

Transformer - 28 to 36 CT, 1A (min)

Capacitors - 35 V

Bridge Rectifier - 100 V, 2 A

C3, C4 - Ceremic, 50V

Caution: Input/ Ground are reversed between the 7812 and 7912