feeders for reverse loopsgreenspun.com : LUSENET : Wiring for DCC : One Thread
am having trouble adding extra feeders to a very long reverse loop...by very long, i mean 20 feet out and 20 feet back...when adding feeders i get a short...i plan to have several other swithes and sidding that will enter and exit the loop tracks...am i overlooking something simple ?
-- j.c.myer (firstname.lastname@example.org), February 26, 2005
One approach would be to isolate or gap a section of track in the loop instead of the whole thing. Say at the end of the wye and 2-3 feet down range. Just make sure its long enough so that anything powered in your train is fully on it before it crosses the second set of gaps. Run only one feeder to this section and wire the reverser in the feeder.
A second way to approach it is to think of the loop as a seperate entity in and of itself. Kind of as if it is its own little layout module when you are done. I wired all my track to one bus and ran all the feeders. After that, I gapped the track at both the entrance AND exit of the loop. As an example, if you use a wye switch for the loop, the tracks at the end of the wye do not get joined to the wye. The loop track and everything in it is now cut off from the rest of the layout. It is no longer connected by joiners to anything else. If you use the buzzer assembly to check for shorts, do it now. In my expiriences, once you wire in the reverser it causes the buzzer to go off.
For an extended length of track and sidings etc as you describe I would wire in the reverser module slightly different. Normally it gets wired into the first feeder in the loop. But, you will most likely have several feeders going to the track from the bus. Thus, I would cut the bus wire just before the first feeder going to the loop track section. Wire in the reverser to span the cut in the bus. Now, every feeder in the loop is subject to a polarity change from the module. If you wired it to one feeder only that would cause the short since the next feeder wires will have the pre-loop polarity. Lastly, if the bus comes back around to the loop exit, do not connect it to the pre-loop bus. Remember this bus wiring should be all by itself connected only by the reverser.
-- Dan Ferrick (DTFerrick@msn.com), February 27, 2005.
Maybe you are overlooking something simple. The length of the reversing loop track section or feeders to it should not cause any problems. I assume that you already have both rails isolated at both ends of the loop (??). But when you add more track feeders to rails inside the reversing loop...
1. Make sure that they are also wired to the 'loop' side of the A-R unit.
2. Make sure that you have the plarity right for each new feeder wire. Remove all locos off that part of the track. Remove the two wires from the loop side of the A-R unit. Place a simple ohmmeter across the rails inside the reversing loop. It should measure infinite ohms. If it measures close to zero, you don't have the polarity right on at least one of the feeder wires. Start disconnecting them until you find the culprit. when you get the wiring straightened out, don't forget to hook the A-R unit back up.
3. An interesting point is illustrated in the latest (April '05) Model Railroader mag about the trip popint of A-R units and the trip point and power availability of various DCC system equipment. You might be having one of those problems.
4. Building sidings or even entire yards into a reversing loop is certainly possible and having more than two entrance/exits points into a reversing track section can certainly be accomodated. Just be sure that your train operations only allow that one set of gaps can be crossed at a time.
-- Don Vollrath (email@example.com), February 28, 2005.