How would I go about making a automatic reverse loop?
First, [#welcome].
Automatic reverse loops are a DCC option, and things don’t work they way in DC. So, before going into a long explanation unnecessarily, are you running DCC, or do you plan to in the near future?
Dcc-digitrax
Hello All,
Which Digitrax command station/booster do you have?
Many Digitrax units have auto-reversing capabilities built-in.
Have you checked the Digitrax website for the capabilities of your unit?
A great investment would be the “Digitrax Big Book of DCC”.
I recently added this book to my model railroading library. Despite its original publication date; 1999, much of the DCC technology has not changed.
Another great addition to your library would be “The Complete Atlas Wiring Book”.
Many have commented that this book is nothing more than a catalog for Atlas products.
Yes, Atlas products are highlighted, just like the Digitrax book showcases Digitrax products.
However, the electrical information and schematics are universal.
The focus of the Atlas book is decidedly DC, but the concepts can be translated to DCC.
The more information you can provide the better the great folks on these forums can help.
Keep the information coming and…
Hope this helps.
The Atlas wiring book is very handy. Particularly useful are the wiring schematics for each of their switch products. You quickly realize why they are still marketed.
If you design your own wiring and switches understanding what is required helps a lot. The schematics do that for you.
Understanding reversing loops is important to understanding the fundamental difference in how they work in DC as compared to DCC. The basic difference is polarity is changed outside the loop in DC while your train is in the loop. For DCC it works better to change the phase of the two rails inside the loop while the train is still inside the loop. It’s easier to automate the phase change for DCC than it is to reverse polarity outside the loop automatically for DC. This is because a momentary short can be used to signal the autoreverser in DCC whereas even a momentary short will stop the locomotive in DC. Optical sensors work better for DC.
Too many words!
To build a reverse loop you need to isolate the loop electrically with insulated rail joiners or simple gaps on both ends and both rails. Then, get an auto-reverser module and connect it per instructions. Simple. You’re done.
You could also do it manually with a DPDT toggle switch.
Rich
And if he wants “automatic” reversing witn NON DCC* he can use a Tortoise at the entrance to the reverse loop. Wire the remainder of the layout (outside the loop) through the DPDT switch provided on the Tortoise and as he aligns the turnout for the “exit” the polarity will have reversed on the track “outside” of the loop.
- Actually, even with DCC, if the layout isn’t very large it could still work through the Tortoise DPDT.
Re: DCC
Oops! I missed his reply to Mr. B! [:$][:$]
Good Luck, Ed
Bear in mind that DC reversing loop wiring changes the polarity on the main. If you use block wiring and automate polarity change using the turnout lining you will lose some flexibility in operating other trains simultaneously if the second train enters the block to be reversed while the first train traverses the reversing loop.
We found this out.
It may help to ensure that the block connecting to the reversing loop is also long enough to accommodate the train but only just long enough.
Hello All,
The OP responded…
If their Digitrax Command Station/Booster supports an auto-reversing function why pay for an item you don’t need?
Seems they are seeking a DCC solution, not a DC one.
Until the OP responds with the model number of the Command Station/Booster all of this is speculation and educated guesses.
Hope this helps.
There is only one track output on the Digitrax booster. It can be either auto reversing or not. So to power the rest of the layout PLUS control a reverse loop, you need an extra device.
–Randy
I have three Digitrax AR1 auto reverse units on my layout. One powers a small yard off of a “wye” and the other two each power a turntable. Installation could not be more simple. Connect the two DCC bus wires to the input side of the AR1, then connect two wires between the output of the AR1 to the reversing section of track. Done!