Subject:
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Re: DCC reversing loops
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Newsgroups:
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lugnet.trains
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Date:
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Fri, 6 Jun 2003 18:34:05 GMT
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Viewed:
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2070 times
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"John Hill" wrote:
> I am sure I saw someone writing about reversing loops but now I can't find
it!
Here, David Koudys made a post about this:
http://news.lugnet.com/org/ca/rtltoronto/?n=7485
> Anyway, this is what I did this evening in about 10 minutes. I cut both • rails
> of a straight track section being careful to get the cuts aligned then did
> another cut through each rail exactly 5 cm (just a tiny bit less than 2 • inches)
> from the first two. So what I have is a 5cm section of track that is • isolated.
> Of course I only cut the metal track and not right through the plastic. I • used
> the finest metal cutting saw I have.
>
> I made two of these then laid a dog's bone track circuit, that is two • track
> loops joined by a single track.
>
> This works perfectly under DCC, the Lego motor wheels are just a bit less • than
> 5cm apart so a motor does not cause a short circuit but the dead section • of
> track is short enough that the train does not stop, in fact on mine the • lights
> do not even blink yet there is no hint of a short circuit.
I tried this and 5cm seems to be the magic number. I did have a little
problem with the center conductor (the one between the cuts) sliding
back and forth and possibly causing a short. To fix it I removed a little
plastic at each end underneath the conductor and pinched the
metal near the bottom. Now it doesn't slide around.
I did notice, however, that there are *five* places that the loco can
loose power if you're going too slow. Here's a diagram (since it might
be difficult to describe with words alone):
http://www.brickshelf.com/gallery/markril/Trains/DCC/reversing-track.jpg
The yellow arrows indicate the cuts. If the the train motor is sitting
precisely at that point, then obviously it won't have power. However,
if you look at the circles in the photo (which represent the train
wheels), you'll see that there are two other places on each side of
the cut section where power can be lost. Of course, if you're going
at even a moderate speed, the loco hardly flinches.
Jeff Elliott suggested an insulated section using tape:
http://news.lugnet.com/org/ca/rtltoronto/?n=7502
I tried this, too, and it works well. Plus it has the advantage of
only having one dead spot. The only concern I might have is the
tape wearing through and getting a short at some point in the
future. Probably just a matter of finding a sturdy enough tape
and inspecting it for wear from time to time.
To mark the reversing tracks, I just put a 4x10 plate on the
ties. It acts as a visual cue to keep up your speed when
passing over that section.
> The 9volt track switches include electrical contacts which must be • bypassed
> either by Lego track power connectors or by doing what I did which was to • solder
> fine jumper wires under the switches so that all 'left' tracks are • electrically
> joined and 'right' tracks likewise.
Thanks for this idea! For illustrative purposes, here's how I ended up
modifying the switches:
http://www.brickshelf.com/gallery/markril/Trains/DCC/switch.jpg
Folder after moderation:
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=44713
> For DCC operation this is all you need to do, no other fancy electronics • or
> extra connectors, just a 5 cm section of isolated track within each loop.
Thanks for the tips John (and others), this really works great. I was
envisioning all sorts of auto-reversing boosters and modules to deal with
this. This is SO simple!
Mark
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Message is in Reply To:
 | | DCC reversing loops
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| I am sure I saw someone writing about reversing loops but now I can't find it! Anyway, this is what I did this evening in about 10 minutes. I cut both rails of a straight track section being careful to get the cuts aligned then did another cut (...) (21 years ago, 5-Jun-03, to lugnet.trains)
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