Nothing!

As long as the DCC decoder is set to "dual mode or analog conversion".  Most if not all current production decoders can operate this way including sound decoders.  You will get the most bang for your buck with a DCC system but DC power will still operate them and take advantage of the decoders features although in very limited form.  The decoders documentation should cover this but usually in a "quick start" format.  More detailed information will be found on the company's website.

Hope this helps

DCC on DC

The power pack will have to be turned up higher when running on DC. It will be noticeable if you have run a DC only loco before.The microprocessor on the decoder needs at least five volts to just wake up and maybe a couple more volts for the loco to move. Some sounds will work automatically.

One company, BLI I think, sells a box to put between the power pack and track that will activate sounds using push buttons.

MRC sells a DC throttle with a bunch of push buttons for sounds.

Rich

Thanks. Whoa Mule

Thanks.

Whoa Mule

Thanks

Thanks