DCC Wye

[dbowers]

Am I correct in assuming that the isolated tail section of a DCC Wye that has an auto reverse module should NOT be connected back to a mainline track and simply terminate in a dead end?

[dbowers]

THX

[jward]

if you have an auto reverse module on your wye, there is no reason you can't extend the tail track to connect to the mainline at some other point. just be sure to gap both rails where it connects to the mainline. the reversing section connected to the autoreverser must be completely isolated from the rest of the track.

[ebtbob]

Good Morning all,

       On my On30 railroad,  I have a large reverse loop.   In the middle of the reversing section is where one of the legs of my wye joins the mainline. 

[Jim Banner]

Bob,
Did you connect the wye to the loop without gapping the rails so that one reverser could handle both the wye and the loop?  Or did you gap the rails and use two reversers, one for the loop and one for the wye?  If the latter, do you find the two reversing fighting it out when you cross from wye to loop?

dbowers,
If the tail track of your wye is isolated i.e. does not connect to anything except the one turnout, then you can save the cost of an a reverser by using a variation of this circuit:
http://members.shaw.ca/sask.rail/dcc/loop/loop.html
Basically, you would chop off the right half of the loop and the two tracks left would connect to your main line.  The track to the left would be your tail track.  In a case like Bob's, it would be better to wire the DPDT switch differently with the ends connected to the two legs and the center to the tail track.

Jim

[ebtbob]

Jim,

        Since I use electofrog turnouts,  every turnout has at least two insolated railjoiner.   The two turnouts that are actually part of the reversing section of the reverse loop are double insulated on both sections the two track end of the turnouts.   The third turnout in the wye,  not a part of of the reverse loop,  has the expected two insulated rail joiners on the inner two rails that meet at the frog.    I have this whole set up running off of one reverser.

[mf5117]

If you just isolate the reverse loop off the Wye .Can you pick up power off the main line to your loop and not use a module as long as your string is not as long as your reverse loop . I think that's what I'm understanding in Jim's Illustration ...

[jward]

to eliminate the autoreverse module and replace it with switch motor contacts, you must have only one entry to the loop, as in jim's diagram. the stub ended tail track of a wye is a similar situation. but if the tail track of the wye connects back into the main at any point, the easiest way to power it is an autoreverse module (assuming the layout is dcc of course).......

[Jim Banner]

Jeffery's succinct explanation is right on.  And if I understand Bob's setup correctly, his tail track does connect to mainline power, but by clever placement of gaps, he needs only one autoreverser to control both the loop and the wye.

Jim

[ebtbob]

Jim,

     To be clear,  there is nothing clever about my set up.   It was just down right lucky.

[Doneldon]

In theory, one can use an autoreverser for more than one
potential dead short place as long as no more than one
such event happens at a time.
                                                      -- D

[mf5117]

So the reason for the reverse module is for . When the front trucks of the loco goes over the isolated part of the loop and the back trucks are still on the loop side it won't cause a short .trying to understand this .

[jward]

when the front truck of the locomotive enters the reversing section, if the "polarity" is wrong it will cause a short circuit. the circuitry in the autoreverser  detects this short and flips the "polarity" to the correct way. i put polarity in quotes because dcc is a form of ac and technically has no polarity. but polarity is a concept many people understand, and isn't too far away from what the autoreverser actually does.

wiring the reversing section through the contacts on the switch motor, on the other hand, matches  the "polarity" of the reversing section with that of the mainline automatically. it also has the added advantage of being compatable with both dc and dcc. autoreverse modules are dcc only.

[dbowers]

THX to all for your responses. This communication is one reason model railroading is so much fun. I have one other question. Mike Polsgrove in his books re: Wiring for DCC,. recommends soldering each rail joint for good continuity but I wonder if the judicious application of the product "Wire Glue" would be acceptable?

[jward]

i am not familiar with wire glue.

i do solder my rail joints both to provide electrical continuity, and to prevent the rails from kinking when i lay the track. i'd also advise multiple feeders if your reversing section is longer than 6 feet (2 sections of fles track, or 8 sections of sectional track.

you could use conductive grease in the rail joints to prevent corrosion and loss of conductivity. i've never used it on a model railroad, but we did use it extensively on the cables for satellite dishes, where the connections are exposed to conditions far worse than any your layout will encounter.