The only RailSounds-equipped set I have is the 1990 Santa Fe Dash-8 set. Included with the set is a small black box with a momentary-action pushbutton on it that says RailSounds. I’ve never wired it into the layout, because there were no instructions - the switch itself said to refer to RailSounds instruction book.
As it is right now, the Railsounds I get with just the transformer are the running-engine sound, the bell, and the horn. Are there other sounds in this old a loco? (well, yeah, technically, the RailSounds are in the boxcar with this set but I figured you’d have guessed this already…).
No,you have it all. If there is a bell button on your transformer you do not need a seperate bell button. Some of the later RS2 tenders have crew talk activated by the transformer.
The 5906 RailSounds button was included with a lot of early RS locos because transformers at the time didn’t have separate whistle and bell buttons. It was wired in series between the hot side of the transformer and the center rail. Like the whistle button, it sent a DC signal to the track, but of the opposite polarity.
The button also can be used with transformers that don’t have either button (e.g., Lionel Z). Although it’s not cataloged anymore, it’s available as a replacement part (610-5906-001, MSRP $13).