Welcome aboard, Dennis!

If you check Lionel's free online catalog, they explain the problems with mixing powered trains from different time periods. Generally, you will not harm a train by running it on an older or newer system--it might not run, but you won't destroy it. Some locomotives can only run on AC, while some can run on either. Remote-controlled trains can be run on an old transformer--you turn the transformer up to full blast and then run the locomotive with your remote control.

Hope this helps.