What is simplest to implement ? What gives best result? Triac or PWM for computerized control of Lionel model trains? How to implement it? (I'm new to Arduino, but not to electronic) I bought an UNO kit
In chapter 2 of Jeremy Blum's Book "Exploring Arduino" he has a section on Pulse Width Modulation. For a model train with a DC motor PWM driving a MOSFET is the best way to go. Triacs are used primarily for AC current.
Here is the link to Jeremy's web site. You may want to get the book and work your way through it. It has been a while since I did but it seems to me that there was a lot of things with application to model rail road electronics.