What happens when a DCC loco has the "polarity" switched

greenspun.com : LUSENET : Wiring for DCC : One Thread

I am curious as to what happens to a DCC equipted loco under the following conditions: 2 DCC locos running on different sections ("blocks") of the mainline. The first loco is being turned around via reversing section. What happens to the 2nd DCC loco running when the "polarity" is switched on the mainline to allow the 1st loco to continue?

-- Robert Maw (bmaw@limited.com), November 11, 2002


The beauty of DCC is that you can run 2 or more locos independantly on the same track. When you tell it to go forward, it goes forward. It doesn't make any difference which way the loco is pointing.

For reversing loops with DCC it is more common to keep the mainline polarity fixed and flip the polarity of only the reversing track section. With DC you needed to flip mainline polarity to keep the loco going in the same 'direction' after the reversing loop turned it around. You don't need to do that with DCC. [re-read the 1st paragraph.] What you do need to do is flip the polarity of the reversing track section to match the main as a loco enters or exits the reverse loop. If the track polarity is quickly switched on a running loco it will simply keep going. "Quickly" = toggle switch or relay...No significant time where ther is no power.

-- Don Vollrath (dvollrath@magnetek.com), November 12, 2002.

Moderation questions? read the FAQ