turntable

[narrowgaugemaster]

on a DC layout how do you get the power of the track onto the turntable onto the roundhouse track?

[lionelsoni]

Roundhouse--wire, same as any track.

Turntable--slip rings and brushes, or just wire if you don't mind limiting rotation to one or two times around.  You could also use the rail under the turntable along with the center pivot.