How come nobody makes a do it yourself install decoder for o scale? Im thinking along the lines of some of the n and ho decoders but made for o scale. I think this would be a good idea if someone wanted to buy a cheap loco and install for themselves, and then just add a speaker.
If you want to add command control try Electric Railroad company, a division of Lionel, as they sell something that is usable with TMCC.
Or you can try using G scale DCC module for your O gauge trains.
Lee Fritz
For DCC? They do.
NCE DCC has the D408SR decoder that does motor/lights only. I used to team those up with a soundtraxx decoder and use the soundtraxx for sound.
I have moved onto using QSI Titan decoders. Even the HO form factor can be handle the current drawn by most modern day models. They make a large-scale version as well, but that's more than likely overkill and may not fit into certain locomotives.
There are other brands as well, but I don't know much about them and prefer the brands I mentioned above.