I'm building my first DCC layout and already have the Zephyr Xtra 3.0 Amp starter set and a Digitrax PM42 for the auto reversing. I you need help however to properly insulate some of the rail joins. I have a two reverse loops with switches in them along with the double slip switch. Most of the information I've read so far in regards to insulating a reverse loop doesn't have a switch going back out to the main oval and this is where I become uncertain about missing an insulated join. Any help would be great appreciated and I've very eager to start building. If there is software the provides electrical information for reverse loop and where to insulate that would also be of great help. Thank you in advance!
I'm going to assume the PM42 will handle two reversing section (although likely only one in active use at a time, perhaps?) One of the Digitrax knowledgeable members can help if there are issues there, so...
I assume the connection that worries you is the one at the top center that leads leftward back to the left loop. If you gap the leftward turnout off the loop on the lower right connection, that would be one pair of gaps, with the isolated reversing section extending downward and to the right to connect with the turnout that control entry to the loop in the lower right corner, with another pair of gaps there at the end of this diagonal line. Note that the other leg will require at least one gap to allow properly switching frog polarity, too.
The loop at the other end of the run seems pretty conventional, so long as the crossings are gapped to isolate this loop. Pairs of gaps on each of the diverging legs just after they separate from the turnout in the lower left.
These sections need to be longer than the longest train you run through if it has metal wheels that will activate the reverser.
Mike Lehman
Urbana, IL
Could this be considered as having one reversing section by gapping each of the tracks leading from the crossing at the very centre?
Bill
It pretty much depends on how you design your bus wiring protocol. If the inner legs of that double slip switch match the polarity of the outer oval, then the two legs of the figure 8 become the two reversing sections.
Rich
Alton Junction
richhotrainIf the inner legs of that double slip switch match the polarity of the outer oval, then the two legs of the figure 8 become the two reversing sections.
Rich,
Thanks for pointing that out. I just figured it was a crossing, probably because my brain just didn't want to think of the complications of it being a double slip instead. That will make things a little tricky without paying close attention to sorting that out if done as a double slip.
The Peco double slip (SL-90) out of the box does have the same polarity on the inner and outter oval. On the packaging information, it suggests insulating the double slip completely when running in a dcc environment. Unfortunately I haven't had time to test out a few options that we suggested for isolating sections of track, I hope to try it out this weekend however. I'm going to post an update picture showing the insulated joints for feedback. Thanks everyone!
jbiss_caUnfortunately I haven't had time to test out a few options that we suggested for isolating sections of track, I hope to try it out this weekend however. I'm going to post an update picture showing the insulated joints for feedback. Thanks everyone!
I do not recommend testing it by wiring it up and turning on the power. If you overlook something, you will have a dead short.
It would be adviseable to indicate the gap locations you intend to install on the drawing prior to turning on the power. That way someone can double check your brain work.
Another good way to check your work is to use two different color feeders, run a gondola with a load painted with your feeder colors on it (such as a scrap piece of wood, one side painted red the other side black). Roll it around your layout. When the sides swap you have a reversing section (which needs to be gapped and the phase swapped (I think thats the correct term).
Both tracks running through your 45 degree crossover are reversing sections.
As suggested, I plan on having the double oval as the main section and gaping the end of the four track sections connected to the middle crossing as showed with yellow lines in the picture. I used a circuit continuity tester on the 45 degree crossing, and each diagonal is independent from the other. I’ll have a total of 3 power sections including the double oval main.
That should work just fine. When I first saw your track diagram in your original post, I traced red and blue lines over the rails to find the mismatched polarities and then circled the locations of the necessary gaps to isolate the two reversing sections. The location of my gaps correspond with the location of your gaps.
From your description, it sounds like the 45 degree crossing is DCC Friendly, and that is critical since the two separate reversing sections intersect at the crossing.
Those look just about right. Don't forget the usual gap on the other leg of the turnouts that are double gapped.
I'm not sure I understand what you mean...
mlehman Don't forget the usual gap on the other leg of the turnouts that are double gapped.
Don't forget the usual gap on the other leg of the turnouts that are double gapped.
jbiss_ca As suggested, I plan on having the double oval as the main section and gaping the end of the four track sections connected to the middle crossing as showed with yellow lines in the picture. I used a circuit continuity tester on the 45 degree crossing, and each diagonal is independent from the other. I’ll have a total of 3 power sections including the double oval main.
It's from the pre-DCC Age, but I ran across a great old article in the July 1972 MR by Linn Westcott (pages 52-54) that remains quite useful when question like this arise, "Gaps and Feeders in Blind Faith." It basically covers what the title says and is available through the MR Archive if you don't have access to an old copy.
While strictly DC in concept, the principles of gapping and feeding at the track level are pretty much the same with DCC. It's short, sweet, and well illustrated with examples that address questions just like the OP's here.