It has been a long time since my last layout and I have a lot of engines that I assume are AC wired, I am working on my benchwork now but my question,s are can I wire AC now and then convert to DC or DCC later? And can I convert my old engines to DC or DCC?
Marklin is the only brand that uses 3-rail AC, so if your locos are not from this brand, they are most likely already DC. Converting Marklin AC locos to DC is not easily done, as you will have to completely re-motor them. I am inclined to say just forget about it.
DC locos can be converted to DCC. In most cases you will have to isolate the motor from the frame and hardwire (i.e. solder) a decoder into them. It can be a little tricky, but it is not impossible.
That cleared a lot of things up. Most of my stuff is atlas, bachmann and some old tyco so I can eliminate the AC aspect.
While going through a box of rolling stock, I found a book I had bought when I was building my first layout. “Wiring Your Layout” by Paul Mallery printed in 1971, I probably purchased the book that year. I have forgotten so much about the hobby and this book will be a good refresher.
All the wiring rules regarding polarity and reversing sections are the same for DC and DCC.
The differences are what you need to control things (blocks and block switches in DC), how you can automate reversing section (auto reversers in DCC) and how heavy of wire you need (generaly heavier bus wires in DCC).
This DCC Primer from Tony’s Trains is very well regarded:
http://www.tonystrains.com/tonystips/dccprimer/index.htm
There is a book by Lionel Strang called DCC Made Easy if you want something printed on paper and bound. I liked it because it gives a bit of the theory of operation of DCC, with the waveform packets and such. You don’t need all of that knowledge to run trains, just like you don’t need to understand a 4-stroke piston cycle to drive a car, but it’s an aid to understanding and kind of interesting in itself, at least to geeks like me.