This my be a lame question but what's the simplest way to control speed on mutipule tracks using 1 supply? or can it be done?
I have answered your question in the General Discussion forum. David's reply is rather cryptic, so allow me to refer you to www.tonystrainexchange.com where you can see a link in blue at upper right called "DCC for beginners". One system, sometimes reversing units where there are conflicting polarities, and sometimes power boosters, but you can run a large enough layout with just the one system if you have it arranged and powered correctly.
Note that each locomotive must have a microchip installed to read the digitial command signals imprinted on the rail power. Adds to the cost, but if you don't want sound in each engine (sound decoders and a speaker or two in the tenders, in the cases of steamers), then simple light-controlling and motor-controlling decoders, as they are called, can be had for about $12 plus shipping and installation of you can't do it yourself.
Crandell
Yup, Same answer as on your other thread. It's best to have only 1 thread on a subject.
Springfield PA
It seems you're new to the forum--welcome.
Just fyi, it does help to keep things in one forum and this is the right place for that question. Also, it helps if you become a follower of your own post--if you want to see the replies quickly. I can't remember if you are or are not on this. I've just seen that most don't bother to follow their own posts.
If you go DCC, may I recommend Digitrax or NCE. I prefer Digitrax.
Just to make sure on something--on DC you can partially control multiple locos on different tracks using one controller with districts/switches--but NOT the speed individually. Just whether one is moving and the other has power killed to it.
Richard