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DCC, Reversing Loco Automaticlly??

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  • Member since
    March 2009
  • From: Harford County, Maryland
  • 86 posts
Posted by mmr1229 on Friday, March 20, 2009 2:51 PM

Thanks for the info i think the locoshuttle will work great. However, was wondering if you might know where i could purchase one?? Checked a couple distributers allready and found none.

  • Member since
    October 2004
  • From: Colorful Colorado
  • 8,639 posts
Posted by Texas Zepher on Monday, March 16, 2009 9:02 PM

mmr1229
i will keep it standard DC with auto reversing. however the next question would be, how to wire it and what would i need?

Once again many ways to do this.

One way to do it is:

1. Electrically break the track into three sections by insulating one rail.  Two short ones on either end and one really long one in between.  The short section is where the loco will be sensed and reversed.

2. Connect a twin-T detector  to each of the short insulated tracks.

3.  Connect the track power to the track through the DPDT contacts of a relay wired as a reversing switch.  When done properly the train should travel in one direction while the relay is off and the other direction when the relay is on.

4. Connect a second relay to the twin-T connector at the end of the track the locomotive goes to when the main direction relay (from #3 above) is off.

5.  Connect the power of the main direction relay to the on-position of the second relay (from #4 above). When the train travels down the track onto the isolated section the twin-T will sense the locomotive, activate the relay which in turn activates the main direction relay and reverses the direction of the locomotive.

6.  Now the tricky part.  As described above as soon as the train left the short isolated track the relay would turn off and the train would again change direction.  Hence just jittering between that tiny section of track, SOOOO   Make the second relay also supply power to itself.   Once tripped this will hold the relay on, and hence the direction relay on allowing the train to run down to the other end of the track.

7.  Now the really tricky part.  Connect a second twin-T to the isolated track at the other end.   Hook a third relay to that twin-T.   Wire the contacts of this relay so that when it is OFF, the power flows through to the coil of the second relay (step #6 above).  When the locomotive hits this section of track, the relay will turn ON and disconnect the second relay.  The second relay will turn off, which turns itself off, and also turns off the main direction relay.  The locomotive reverses direction travels all the way back down the track and the cycle repeats.

--- One can substitute any form of detection instead of the twin-Ts.  Optical, reed switches, whatever.... ---

All the parts for this are available from Radio-Shack.  Even the ones to scratch build the twin-Ts if so desired.  I made one for a demo layout a few years back I believe it cost about $15 in parts where most of it was consumed by the relays.
 

  • Member since
    March 2009
  • From: Harford County, Maryland
  • 86 posts
Posted by mmr1229 on Monday, March 16, 2009 4:05 PM

no, i have no block detection or a computer. the extra track is a stand alone track so i guess as a few of you said i will keep it standard DC with auto reversing. however the next question would be, how to wire it and what would i need?

  • Member since
    May 2008
  • 4,612 posts
Posted by Hamltnblue on Monday, March 16, 2009 3:28 PM
If you get one of the BLI paragon 2's they have a learn feature that will playback. You run it with record mode mode on then tell it to repeat indefinitely. I don't know if over time it will work it's way further one way or the other though.

Springfield PA

  • Member since
    December 2004
  • From: Pa.
  • 3,361 posts
Posted by DigitalGriffin on Monday, March 16, 2009 1:02 PM

Every command (with the exception of global STOP) in DCC requires the command contain the engine number.

The problem there is no way for the DCC controller to know which train has occupied which block.  (Transponding aside)  Without this information, you can't tell which train to reverse, and which train to keep going.  Even if you have transponding with block detection, you'll need a computer program.

If you only plan to run 1 train on that straight line, then DC autoreversing would be a better option.

Don - Specializing in layout DC->DCC conversions

Modeling C&O transition era and steel industries There's Nothing Like Big Steam!

  • Member since
    March 2007
  • From: College Station, TX
  • 675 posts
Posted by Arjay1969 on Monday, March 16, 2009 9:49 AM

 Is this straight section connected to the rest of the layout, or is it completely independent?  If it's independent, you'd be better off using a DC reversing circuit and forgetting about DCC on that stretch.  Automatic reversing like that on DCC can get a bit complicated (and expensive), where a simple DC reverser can be had/built for a few dollars.

If it's connected to the rest of the layout, the LocoShuttle seems like your best bet.

Robert Beaty

The Laughing Hippie

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The CF-7...a waste of a perfectly good F-unit!

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Then it comes to be that the soothing light at the

end of your tunnel, Was just a freight train coming

your way.          -Metallica, No Leaf Clover

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  • Member since
    October 2004
  • From: Colorful Colorado
  • 8,639 posts
Posted by Texas Zepher on Sunday, March 15, 2009 5:31 PM
mmr1229
I currentlly have a zepher system from Digitrax and it works great, however I'm adding another section to my layout that will consist of one long straight peice of track, not a loop. What I'm hoping I can do is reverse the direction of the locomotive automaticlly so it will run itself in a straight line back and forth from one end to the other. If this is possible I would appreciate any info regarding this.
Yes, this is possible and there are more ways to do it than one can shake a stick at.  So the first question would be as another user indicated.   Is there already a computer hooked to the DCC system?   Do you have any form of block detection today?  
  • Member since
    February 2007
  • From: Christiana, TN
  • 2,134 posts
Posted by CSX Robert on Saturday, March 14, 2009 7:11 PM

You need a LocoShuttle.

  • Member since
    March 2009
  • From: Harford County, Maryland
  • 86 posts
DCC, Reversing Loco Automaticlly??
Posted by mmr1229 on Saturday, March 14, 2009 3:43 PM

I currentlly have a zepher system from Digitrax and it works great, however I'm adding another section to my layout that will consist of one long straight peice of track, not a loop. What I'm hoping I can do is reverse the direction of the locomotive automaticlly so it will run itself in a straight line back and forth from one end to the other. If this is possible I would appreciate any info regarding this.

 Thank you, mmr

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