[Nonfractal]

The variable resistance of the track wiring/rails is present all the time, I can't understand why adding some resistance  in the controller/separate box would make a difference.
In practical terms what is different about the brake behaviour between the 2 methods?


Joel

"The variable resistance of the track wiring/rails is present all the time,"
- If you have anything less than infinite resistance between the rails "all the time",  this is a short circuit  and the track won't be able to power the cars.

"I can't understand why adding some resistance  in the controller/separate box would make a difference"
-When a dc motor is open circuit, no current can flow in the coil., If no current flows, no backEMF can be produced
-When a dc motor is closed circuit (shorted across the contacts) current flows through the coil producing a backEMF causing the motor to resist being turned.

Between the 2 extremes, the level of backEMF can be controlled by introducing a resistance between the motor contacts.
The resistance allows some current to flow. A variable resistance can produce various amounts of backEMF.

"In practical terms what is different about the brake behaviour between the 2 methods?
- diodes drop a fixed voltage 
- resistors drop voltage dependant on the amount of current flowing. 

In practical terms, control of diode based braking should be less impacted by the motor being used.

Alan