I added a Blue Line Snail controller to the top level of the 2x4 N scale model railroad and supplied power to it with a 9V battery. This way I can remove the top level, place it on any table or desk, and operate it without needing an AC adapter. However, you could just as easily supply power with an AC adapter as well. ►Here is the controller I used from Z Track Center: https://ztrackcenter.com/electronics/controllers/AN-1-SAC ►The building kits I used: https://amzn.to/3BsZM