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Discussion Starter #1
Years ago when I used DC I had a reversing loop on my layout. At that time there was a device that I wired into the track to reverse the polarity when the engine entered the reversing loop. Nowadays since DCC is run on ac ( I believe) and the direction decisions are made "on board" is there any special wiring to be done for a reversing loop when using DCC?
 

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you still have to isolate that section , and use a 'polarity switcher', either a manual switch, or an automatic switcher ... that's about it ..
 

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The only difference between DC and DCC is that the former has a polarity conflict at the meeting point of a reversing loop, while in DCC it's technically a 'phase' conflict. Same diff, though, in terms of rectification; you need a reverser. Either a DPDT toggle correctly wired to reverse the polarity/phase or an automatic (digital these days) reverser such as those made by NCE, MRC, and Digital Specialties. The same general rules about gapping the rails at both ends applies, although staggered gaps and double gaps can extend the reversing de-conflicting action for trains longer than the length of the loop to each pair of gaps. Yeah, that sounds heady, or fuzzy, but it's pretty straightforward once you begin to analyze the concept if you don't want short trains to have to fit inside of a short loop.
 

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Staggered gaps? I haven't heard of this technique, can you give a quick explanation about what that does?
 

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There is no difference in wiring tracks or even reversing loops
for DCC...the principle is the same...you must avoid short circuits
due to the different AC phase of DCC or the different polarity of DC.

The modern reverse loop controllers sense the short circuit caused
by the loco entering the 'isolated' section and immediately reverses
the phase of the iso selection...when the loco reaches the other
end of the iso section it's wheels again cause a 'short' that again
causes the reverse loop controller to reverse the phase of the
iso section. Since loco direction is controlled by the on board
DCC decoder there is no effect to the loco...it runs smoothly
thru and you don't even see it's headlight flicker.

Unless you expect to run trains longer than the
'isolated' section AND with metal wheels in the reversing situation there is no need for
staggered gaps or other complications. You do need to use
insulated joiners in both rails however.

Staggered gaps means that the left rail gap is perhaps an inch forward of
the left rail gap. Here again, tho, the metal wheels spanning any gap between
the main track and the isolated section would
cause the automatic reverser to react.

Don
 

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Here's what I do: Mount a simple DPDT toggle switch in the the most convenient place for when you deal with the situ.
There are 6 posts under it.. To make it a reversing device, solder wires, one from upper left post to lower right post...Then solder one from upper right post to lower left post. This makes an X shape.. With your reverse loop track gapped where it leaves the turnout and where it re-enters the turnout (both rails/4 gaps), run 2 wires from either end of the toggle (two adjacent corner posts) to the rails in the said loop..From the remaining 2 blank center posts run wires to any rails outside the loop..This is the power source to the loop.
With nothing done yet, run the train into the loop.. Anytime while train/loco is in the loop, throw the toggle..The train will continue on and out the loop as if nothing was done..... You do not have to stop the train anywhere, but do make sure turnout has been thrown for the ensuing exile from the loop..
 

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Staggered gaps? I haven't heard of this technique, can you give a quick explanation about what that does?
What you want is only one metal tire passing over one gap at any one time. This helps to minimize 'confusion' by the digital reversers that have sensitivity to rushes of current (amperage) over the rails that, in turn, will toast an expensive decoder. It also minimizes the chance of high-temperature arcing at gaps that are accurately opposite each other transversely when two metal tires bridge the gaps concurrently. Note that other manufacturers/suppliers of auto-reversers do not mention or suggest staggering gaps, only Digital Specialties which makes the high-tech gee-whizziest reversers and circuit breakers for the hobby. If you google, "PSX-AR manual), and read comprehensively (maybe 7 minutes or so) the entire manual, you'll come away with a better understanding of their thinking.
 

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Discussion Starter #8
Great Responses Thanks
Recommendation on digital reversing modules?
 

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You can use any brand Reverse loop controller. They
are all about the same quality. Shop for the best
price. It's all automatic. Once you install it you can
forget about it. You won't even know it's there. Many
of us install it under table near the isolated section
it controls. Connect your DCC bus to it's input. Connect
your isolated track section to it's output. That's all there is
to it.

Don
 
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