Tuesday, February 14, 2017

Tuesday Tip: DC on a DCC Layout

Like many of you, I have a "few" (well...) engines that aren't yet converted to DCC and lately I've been on the lookout for out-of-production New Haven steam locomotive models which rarely have decoders already installed. So, instead of being limited to just a short test track to run these on, I decided to make the "Air Line" dual-mode: I can easily switch from DCC to DC and back again at the flip of a (couple of) switch(es).

Long-time readers will recognize the "Air Line" as two 2x8 modules/towns that I use, operationally, to represent the Air Line of the New Haven that started at Cedar Hill Yard and went northeast through Middletown, across the Connecticut River into Portland, through Willimantic, Putnam, and ultimately to Boston. By my era, it - like the Valley Line - was relegated to a not-so-lowly branch: it was a popular haunt of many late-steam-era fantrips, not to mention the famous Ghost Train.

But that's all a story for another time. Click here for a quick tour of the fictional towns of Somerset and Mill Hollow on my Air Line stand-in. Read on for my dual-mode switches.

Fist, it's important to note that the Air Line is an electrical branchline too - it's "dead-end" electrically. The main bus wires come from the command station under Middletown, run the length of the two modules, and then end.  So all I had to do was cut-in an on-off (DPDT) toggle switch into the bus. That was a simple matter of soldering four wires to the switch, cutting the bus wires, and joining the wires with wire nuts. Other than the wiring, the most important part of this install is to clearly label this switch so you know what it does - this switch cuts out the DCC (which I discovered was necessary even if the DCC/command station is off. Something about back-feeding electricity or something...).

The switch above was installed the same way, but it's in-line between my DC power supply (a Control Master 20 on that makeshift shelf) and the bus wires (incidentally, that smaller gold power pack supplies power to the turnout in the tunnel at Somerset. The AC terminals on the CM20 power the structure lights on the modules).

So all I have to do to change from DCC to DC power on the modules is turn off the DCC at one switch, and turn on the DC at the other switch (and turn on the CM20 of course). Easy!

Lastly, the CM 20 allows for walk-around operation using regular phone jacks/cords. Pretty innovative for the time. Only problem is that my NCE cab bus also uses phone-type jacks. There are only two CM20/DC jacks (one on each module), but a little bit of labeling keeps folks from getting confused (thanks to Roman for the labeler!).

So I gotta know - does anybody else these days even bother to have DC along with their DCC? If so, do you have separate layouts, or did you do something similar to what I did?

If you want to have your cake and eat it too, give this approach a try - and if you do, be sure to let me know in the comments!


  1. Hi Chris,

    I think that is an excellent plan. There is a lot of locomotive out there with out DCC and it is nice to have a section of the railroad to operate them. I know I have number o locomotive that still need to be converted, and there is a significant amount of time and money to convert them. Can DC locos get into Middletown?


    1. Unfortunately, no - the "break" in the bus occurs a short distance "east/northeast" of Mill Hollow on the way to Middletown - just enough track to have a sufficient "tail track" for switching and run-arounds. I haven't (yet) discovered what happens if I accidentally go over that gap...

  2. As you know, but your readers probably don't, my entire layout can operate on DC or DCC. My DC and DCC controllers sit side-by-side with a similar switch that determines which is in use. Mine is a three-way-toggle, so I have a middle position (which I default to) so no power goes to the track when I first turn on the controllers. All I have is a standard MRC Tech II DC Power Pack, no walk-arounds.

    The main reason I bothered to install it was not only to test the locomotives themselves, but so I could thoroughly test ALL mainline trackage with the brass steam locomotives to make sure they would operate on the layout. So it's more about testing the layout for me, than the locomotives themselves.

    This was one of the great advantages of using Microengineering flex track. Since it stays put without having to be tacked or glued down, I could lay track, test it will all of the steam locomotives, and when I was confident that it was operating properly, glue it down. You can't do that with Atlas flex track.

    I did the same thing on the prior layout - the entire mainline was in place (on masonite spline) and not permanently attached at all by track nails or glue for months. I didn't get much farther than that, but it allowed me to lay all of the mainline, with no turnouts, for testing. Then I could cut in (I was handlaying in place) the turnouts once I know the layout operated well. At that time it was only DC. Although I knew it would eventually be DCC, I hadn't gotten that far yet.