First I want to thank everone for their input and help.

   The easest way for me to solve this problem was to obtain a Lionel DC Converter Box Part # 8-82116 its use for large scale Lionel Engines since they run on DC current. This Convertor has been specifically designed to convert alternating (AC) to direct current (DC) from 0-30 volts and is equipped with an 8 amp circuit breaker.The convertor is compatiable with AC output transformers operting between 0-30 volts.

Need a diagram to built a rectifier circuit. Need to rectifive 18 volts ac to 18 volts dc. 2 amps.

What rating for the following:

Bridge rectifier

Electrolytic Capacitor

Voltage regulator