AC confused

The AC input is rectified immediately going to the board by bridge rectifiers.  Regulated 5 volt DC or whatever goes to the chips on the PC board. Motor voltage is provided by a larger bridge rectifier on more conventional boards. Not sure how it is done with legacy. Polarity is reversed to change direction. Without any board a bridge rectifier to the motor will run it in one direction. 

A DC offset on the AC blows the whistle in conventional operation.

Dale H

TMCC & Legacy need AC to function, MTH DCS newer boards run on AC or DC.  Many, but I'm sure not all, conventional electronic E-Units will run on AC or DC.  The Lionel AC Pulmore motor will run on DC without any problem.

Thank you very much, gentlemen.

Thanks for clearing the fog in my thought processes.

Do you think the days of AC supply to the track are numbered, or will some kind of parallel evolution continue?

Since Legacy requires AC on the tracks, it's not numbered at my house.

For early Lionel TMCC and Legacy board they take AC in and half rectify to make DC to run a 5VDC regulator and power the microchips.  The AC passed through for motor and accessory control since early TMCC was the universal motor.

When can motors requiring DC were used the AC for the motor was rectified with a FWBR and used for the motor.

Later legacy and MTH system are DC based.  They take the AC in and immediately rectify it to DC to drive both microcontrollers off a regulator and power motor and accessories.

You really need to look at the board to see which method is used, but that is the basics.  G