Hey all,
I am just getting back into the hobby and considering a DCC for my layout. I understand most of what i need to know but i do have a question. How do you wire a reversing loop in a DCC set-up? Does the decoder change the polarity for you or does it have to be wired just like a conventional reversing loop? I understand how to run two wires under the layout and feed the rails in several spots to prevent voltage drops etc. (I work as an industrial maintenance tech) Thanks for the help.
Wire your reversing loop as if you were running conventional DC. Some DCC manufacturers make an automatic reversing loop controller, but I just use a double-pole, double-throw toggle switch. If you don’t reverse the DCC signal’s polarity, a short will develop as soon as your locomotive’s wheels cross the insulated joiners.
Do NOT waste time, money, annoyances, etc by wiring a DCC reverse loop like a conventional DC reverse loop.
All that is required is a section of the loop, longer that your longest locomotive consist be gapped, both rails, both ends. This section is the connect only to the output side of a DCC Automatic Reverser. The input to the reverser is from your bus wires.
The DCC Automatic Reverser works by detecting the short very very quickly, a switching the polarity to the rails.
As Nigel says a DCC reversing loop is a wonderful thing. An AR1 from Digitrax cost about $24 (same for MRC) and it’s a snap to install.
Once installed you’ll never have to think about the reversing loop.
Take a look:
http://www.trainweb.org/silversanjuan/Page3/Page14.html
[:)]
So, the AR1, or any other auto reverse decoder completely does away with any need for extra power stations for the loops? My dcc info is Stan Ames’ Digital Command Control 1998. I’d far rather buy one or two auto reverse decoders than one or two power stations.
That is quite correct. [:)]
“Oh frabjous day, calooh, callay, he chortled in his joy” One less jabberwock, and a whole lot more budget for stuff that can run around on the layout! Thanks jwmurrayjr for this news. I’ll take a look at that site too. [8D][^][^][bow][bow][tup][tup]
Do NOT under any circumstances wire a DCC reverse loop as you would a DC loop. You’ll be missing one of the really great thngs about DCC. I have three and use Tony’s PS reverse units. Trains just fly around the loops non stop, don’t miss a beat. Great.
Only thing you want to make sure to do is make the loop longer than the longest consist you’ll be running. And if you’re running lighted passenger cars, the loop needs to be longer than the train.
The loop is wired as a separate block, insulated at both ends. The PS reverse connects between the original power buss and the one for the loop. Very simple.
Yes, it’s true that an automatic reverser can be used if you run ONLY DCC, but if you think you might ever want to run something that does not have a decoder installed, an automatic reverser won’t work, since they are for DCC only. On our club layout, we can run either way, so toggle switches had to be used to reverse polarity. With a little bit more complicated wiring and use of a triple-throw switch, it might even be possible to wire a layout for both DC and DCC operation where the toggle switch is used to reverse polarity when running on DC, and the automatic reverser kicks in when running DCC, but there is a risk of operators getting confused and turning on the automatic reverser when running DC. Without actually risking burning out an automatic reverser by seeing what happens when it is fed DC, I had to settle for the toggle switches.
I have installed MRC reversing decoders on my loops and they work great!