@bmoran4, @Norton, The issue of DC current to the track is not so clear cut. Currently all the LionChief train sets are listed by Lionel as being able to run on either AC or DC current.
I don't know... Lionel's catalog descriptions are not clear on this, but aren't the wall warts that come with the train sets DC powered? I looked in the 2016 catalog and there's no mention as to whether the wall warts put out AC or DC. Most wall warts I've ever seen put out DC current.
During the 1990's most Lionel train sets (and K-Line train sets) were advertised as being able to run on AC or DC current. But as bmoran4 correctly pointed out, you do need to look at a specific locomotive's instructions to know whether or not DC is safe for that particular locomotive. I know some of the engines that came with Lionel's "Trainsounds" have a warning to not use DC.
But it is certainly not clear cut anymore. Some products have been made with DC capacity and some have not. As a general rule, the Lionel engines that will run on DC say "AC/DC operation" in the catalog.
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I do have the option of running my layout on AC or DC current, which I have done because I have a bunch of non-command smaller, low cost engines with no sound boards (I have sounds that are on the layout, not on specific engines). By removing circuit board reverse units out of the small engines and adding additional weight, these engines run MUCH better and will pull more than 2-3 cars.
We've seen posts where guys have a filed circuit board and it is suggest that they wire in a rectifier and run the engine forward only. In my thinking, if I'm going to do that, well I'd rather have a DC power source and be able to run the engine forward and reverse at least.
But as with anything else in life, you make choices. I know I am not going to be running larger engines, or engines with command of any kind. I've made a decision that works for me just fine.