I would try that first.
If you are going run a lot of locos and turnouts, you might consider Bachmann's E-Z Command booster which would give you 5 amps compared to the 1 amp E-Z Command unit.

Maybe this will help.
I had a problem when I was switching controllers around only mine would not go in reverse, only forward. It ended up being the power pack.
It happened when I tried to use the E-Z Command power pack with a DC controller for a DC loco.
The problem was that the E-Z Command power pack puts out DC voltage while a DC power pack puts out AC voltage.
This is the whole thread here.
https://www.bachmanntrains.com/home-usa/board/index.php/topic,38434.15.html

I don't know hat happened. I can't either.

I had never seen video of John Allen's Gorre & Daphetid layout before.

The whole train

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The lighted cars

The tree car

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The toy car.

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The present car.

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Lit up.

Thanks. I'm just going tog with battery power. It will be less complicated. I'm only doing three cars.
I have the tree one about finished.I have one with toys that I did today. The one with presents is close to being done.

I might put an elf on the box. I have some miniature garland coming to  put on the car around the trees.

You still have to buy the sound card. My first Mogul that I got some years ago was well over $200.

Thanks Jeff. I'll stick with the batteries.

I'm trying to do that. I have to make sure the switch is accessible.
The one gondola has the trees.. I had to fit all the wires in there. I cut down the AAA battery box to keep just the switch. I used CR2032 batteries for power instead because they are smaller. Then, I covered the wires with pieces of styrene. I couldn't shorten the wires because they are so small and soldering them would have been impossible for me to do.

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Just my opinion but you might be better off with a new loco than you can switch shells with. I bought a new PRR Mogul from Trainworld for $109. It is DCC and sound ready meaning it already has a speaker in the tender. You just need the sound module. For what it will cost you to get all the stuff you need to convert your old one like decoder, speaker, etc. it might be worth it.

DCC track power for the On30 Mogul which is pulling these. I switch controllers when I'm running DC stuff but I don't have any DC On30 locos.
I'm thinking I'd better off just staying with batteries. I thought it would be easy to just add like 1000 ohm resistor. It's hard to hide the batteries. I have two more cars to do - another gondola and another flat with different type of light strings.
No other specs on the lights. The batteries are 3 volts. That's how I know they are 3 volts.