I'll show you a working diagram: how to convert 230V AC to 5V DC. You can also convert 120V AC, 60 Hz to 5V DC. Your secondary voltage would be 9.598 VAC. After you see my video you will be able to build one yourself.

Parts List:
1 - Class 2 Transformer, 20VA, 120VAC, 24VAC (Cost: $6.81,Part #: G2073206)
1 - MDA2500 Bridge Rectifier (or 4 - 1N4001 Diodes)
1 - 470uf Electrolytic Capacitor, 35V
2 - 0.1uf Capacitor
1 - LM7805 Voltage Regulator