DC/DCC Wiring

Donstaff Mar 7, 2014

  1. Donstaff

    Donstaff TrainBoard Member

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    So far, so good. I understand that.. In fact, I have a great example: If I'm running a DC loco slowly on this level and take the crossover, it stops at the point that the front trucks venture across the insulated center point of the crossover. I can then pull the loco across the insulated point and if I switch the direction on the power pack, the loco continues in the forward direction. So what we want is for the reversing modules to automatically do this for us.
     
  2. PaulBeinert

    PaulBeinert TrainBoard Supporter

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    Absolutely and that is exactly what the PSX-AR will do for you at the gaps when running DCC.
    Under DC, you will flip the DPDT for the next block to align the polarity.

    but with the way I show it wired, this will happen at the gaps not in the crossover
     
  3. RT_Coker

    RT_Coker TrainBoard Supporter

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    The center part of the crossover would be the ideal place for the auto-reverse unit, if it were not such an extremely short section of track. That is why the crossover is typically wired so that the crossover path can be used without the DC (or DCC) loco stopping.

    The crossover and adjacent track could also be wired as two independent track sections (a top section and a bottom section). One section would then have to be controlled by a reverser (a switch for DC and an auto-reverser for DCC). Then the DC loco could run the loop without stopping (assuming the switch for DC reversing is in the correct position). The DC loco could also cross the crossover after it is stopped and then the switch for DC reversing is put into the correct position. Of course the auto-reversing unit would allow the DCC loco to run either path without stopping.
    You are the only one that really knows your layout and what you are aiming for, so you are the best person to take this information and apply (or not apply) it to your layout.
    Bob
     
  4. PaulBeinert

    PaulBeinert TrainBoard Supporter

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    The general practice is for reversing loops to be long enough for the longest train that will use it.
    I was thinking that the crossover could be powered by a PSX-AR but then the design wouldn't work for DC.
     
  5. RT_Coker

    RT_Coker TrainBoard Supporter

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    Here is one way this layout level could have the track sections separated and wired. It shows what may be the simplest way as an example that can maybe help you figure out what you want. It also assumes that the original power connections and added track-isolation-gaps are not present.
    If I am not mistaken your Kato crossover is isolated so that all four track-connections are electrically independent of each other. This is represented by the red-circle on this crossover. The two other red circles are track-isolation-gaps that divide the track into top and bottom track-sections of as near equal track length as practical. The green connections provide fixed-phased power to the top track-section and adjustable-phase power to the bottom track-section. The black-box contains a switch(s) that can be set to provide the same (and reversed) fixed phased-power for DC operation or power through an auto-reversing unit for DCC operation.
    Bob
     

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  6. BarstowRick

    BarstowRick TrainBoard Supporter

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    I know late to the party and almost everyone as already gone home.

    First off I would never cross over a locomotive from analog DC to DCC. This has the potential of decoding the decoder or better said shutting it down. On BarstowRick.com and here at TrainBoard.com, I talk about how I wired in my layout before the advent of DCC. Explaining how easy it was to add DCC. I started out with Cab A and Cab B, DPDT Block Wiring. It was easy as pie to convert to DCC. However, I only operate one option at a time. Seldom running my Analog DC fleet of diesels simultaneously with my DCC fleet of diesels. Feel free to check it out. http://www.barstowrick.com/category/dcc-dpdt-cab-a-b-wiring/

    Incidentally your picture of your layout did not come through on my computer. You might be using a newer program then what's available on my computer.

    No this isn't an April Fool's Joke.
     
    Last edited by a moderator: Apr 1, 2015
  7. RT_Coker

    RT_Coker TrainBoard Supporter

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    Donstaff,
    On another forum you ask about a “DPDT relay controlled by the crossover”.

    Here is another way this layout level could have the track sections separated and wired. It shows what may be the simplest way as an example that can maybe help you figure out what you want. It also assumes that the original power connections and added track-isolation-gaps are not present.
    If I am not mistaken your Kato crossover is isolated so that all four track-connections are electrically independent of each other. This is represented by the red-circle on this crossover. The green connections provide fixed-phased power to the right track-section and adjustable-phase power to the left track-section. The black-box contains the “DPDT relay controlled by the crossover”.
    The crossover is set for either a dog-bone loop or a figure-eight loop, and the relay sets the phase of the left track section accordingly. Of course for safe operation the train should typically be inside one section when the crossover is changed, and DC trains inside the left track section should be stopped first.

    Bob
     

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    Last edited by a moderator: Apr 3, 2015
  8. Donstaff

    Donstaff TrainBoard Member

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    Rick, which idea? Are you saying that your idea of he black-box containing a switch(s) that can be set to provide the same (and reversed) fixed phased-power for DC operation or power through an auto-reversing unit for DCC operation was not a good idea?.
     
  9. Donstaff

    Donstaff TrainBoard Member

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  10. PaulBeinert

    PaulBeinert TrainBoard Supporter

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    Don,
    Have you tried any of the suggestions?
     
  11. Donstaff

    Donstaff TrainBoard Member

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    Paul,
    I have decided on decided on the "black box" with the DPDT latching relay. I'm still talking with Mouser to determine the exact model. Do you know which one?
     
  12. PaulBeinert

    PaulBeinert TrainBoard Supporter

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    Don,
    I don't know anything about black boxes. Does the black box solution allow for both DC & DCC (with reversing loops)?
     
  13. Donstaff

    Donstaff TrainBoard Member

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    Paul,

    The black box referred to a black box that was drawn on my drawing, showing the location for placement of a DPDT relay on level 3 of my track plan (see attached). This was from a different forum.

    I received replies from DonR and Bob on ModelTrain Forum.com, recommending the use of a DPDT latching relay instead of reversing modules as a solution that would work for both DC and DCC. DonR wrote:

    "Don,
    [TABLE="class: tborder, width: 100%, align: center"]
    [TR]
    [TD="class: alt1, bgcolor: #FFFFFF"]The DPDT relay is to be controlled by the double cross over
    motors. Tortoise uses 'stall' motors, so they are controlled
    by a simple SPDT switch, the power stays on to the motor
    even after it completes the throw. That power would hold in
    a simply DPDT relay, and release it when thrown the
    other way, thus reversing the phase/polarity of the left loop.

    The Twin Coil machines are controlled by a momentary
    push button. The power is off after the throw is completed.
    Thus you would need a twin coil DPDT LATCHING relay that would
    pull in AND STAY IN until the other coil is activated when the
    push button changes the points again.

    The information on the Kato turnout motors is not all that
    clear but they seem to be the twin coil type which uses a momentary
    push button or switch. The instructions to your crossover should
    give you correct information or a KATO N scale user could tell us
    for sure.

    If they are twin coil, you would need a LATCHING DPDT relay. They
    are readily available from electronic supply houses. You would need
    one with 12-14 Volt Coils and DC or AC depending on your turnout
    motor supply source. The Relay contacts should have at least a
    5 amp capability at 14 to 20 volts.

    Both rails of both straight tracks on the DOUBLE CROSSOVER would
    have to be gapped. I couldn't tell from the pic but it looked like
    only one was in each straight track. A razor saw or dremel cutting
    wheel could cut whatever is needed.

    All of the insulated joiners that you have indicated in your
    drawing would no longer
    be desirable. The entire left loop would be fed by the DPDT relay.
    The entire right loop would always stay the same polarity/phase.
    So only the gaps cut into the crossover straight tracks where
    Bob shows the blue line are all that should exist.

    Don"

    I have not, however, been able to locate a latching DPDT relay with the correct specifications. I believe that this is a workable solution and would appreciate your opinion.

    Donstaff


    [/TD]
    [/TR]
    [/TABLE]
     

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  14. PaulBeinert

    PaulBeinert TrainBoard Supporter

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    Without an actual wiring diagram, this Latching DPDT Relay confuses me so I cannot comment on it.

    From a DC perspective, you have 3 blocks (left loop, double crossover, right loop), each of these would require a DPDT for block control.
    From a DCC perspective, you still have the same 3 blocks but the would have a static polarity and the 2 loops would have auto-reversers.
    To accommodate both DC and DCC, you just need a way to switch from auto-reversers to the DPDT control for the loops. Diagramming that would be fairly simple.
     
  15. PaulBeinert

    PaulBeinert TrainBoard Supporter

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    Don,
    Had some free time this morning so I drew up the wiring diagram that goes with my solution to having bot DC & DCC on the 3rd level
    The A & B wires on the top go the rails.

    DC DCC DPDTs.jpg
     
  16. RT_Coker

    RT_Coker TrainBoard Supporter

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    Paul,
    This might help explain what Don is trying to do.
    A red-black line drawing of a switchable dog-bone/figure-eight loop. When the double-crossover switch is changed the phase (or polarity) of the left half of the loop is also reversed. The blue line is where the rails are gapped. The right half power feed is a fixed polarity connection and the left half is a reversible polarity connection through a DPDT relay that is switched in conjunction with the switching of all four turn-outs of the double-crossover.

    The loop can obviously be set up as either a dog-bone or a figure-eight without any problems for DC or DCC. As a dog-bone the left and right outer most rails of the loop are the same phase (say + DC). As a figure-eight the left and right outer most rails of the layout would be opposite phases. So if the double crossover is setup only to operate loop as a dog-bone or a figure-eight, and switching the double-crossover also switches the phase of the complete left side of the loop (with say a DPDT relay), then there is a switchable choose between dog-bone and figure-eight that works for both DC & DCC (provided the DC trains in the left track-section are first stop for this switch). The phase of the complete right side of the loop stays fixed because of the DC/DCC track that exits this level. The only rail-gaps that are actually used are those of the double-crossover.

    Bob
     

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  17. Donstaff

    Donstaff TrainBoard Member

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    Bob,
    I am still searching for the right DPDT latching relay. Wonder if this works for trains going in either direction as long as the DC trains in the left track-section are first stop for this switch. Also, would a 12V. wall wart with a votage doubler work with a 24V. relay?
    DonStaff
     
  18. RT_Coker

    RT_Coker TrainBoard Supporter

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    Yes
    I am not a relay expert. But I would look for a DC-controled latching-relay and feed it with the same connection that goes to the double-crossover. What voltage is going to the switch that switches your double-crossover? Does this control send a continuous or momentary DC voltage to the double-crossover?

    Bob
     
  19. PaulBeinert

    PaulBeinert TrainBoard Supporter

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    Bob,
    While I am still studying this design, I do not see how this will work smoothly under DC when using the left side as a reversing loop to head back down to the 2nd level.
    Having traveled up from level 2, I am clockwise on the right hand loop and go straight through the double crossover to be clockwise in the left hand loop. At that point the relay gets thrown and the train proceeds to back up?
     
    Last edited by a moderator: Apr 12, 2015
  20. RT_Coker

    RT_Coker TrainBoard Supporter

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    Paul,
    Start with loop in dog-bone. Stop clockwise-going DC train on left side. Switch double-crossover and DPDT relay changing DC polarity of left side. Change direction switch on DC throttle to compensate for DC polarity change and to keep train going in same direction. Proceed on figure-eight over crossover onto bottom left side and then down to other levels. Starting with figure-eight and the switching to dog-bone would also work.
    Bob
     

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