Wiring a New DCC Layout or Converting to DCC a Layout that is Currently Wired for DC

This page gives a very brief explanation of the advantages of DCC, how DCC works, and finally how to use the Atlas DCC wiring diagrams to either build a new Atlas DCC layout or convert to DCC an existing Atlas layout that is currently wired for DC operation.

Advantages of DCC
The many advantages of DCC include:

  1. You can control individual locomotives rather than controlling the power to track sections. Hence, you can run a number of locomotives independently (with different speeds and directions) on the same track.
  2. Although you probably will still need some blocks (called power districts in DCC) to isolate sections of your layout from shorts, there are likely to be many fewer DCC power districts than there were DC blocks. Hence, you will have many fewer block switches and much less block wiring to install. If you have reversing sections, you will find that there is only about half as much wiring with DCC as there is with DC.
  3. You can program DCC-equipped locomotives so that they operate as a single consist. Also you can adjust the characteristics of the locomotives in the consist so that they all operate at the same speed.
  4. If you wish, you can operate turnouts from your DCC system.
  5. If you purchase an automatic reverse loop control unit, you can completely automate a train traversing a reversing section.

How DCC Works
Two major differences between DC and DCC operation are

  1. In DCC, there is a constant voltages on the rails at all times
  2. You specify how the locomotive is to behave (speed, direction, sounds, etc) by sending digital commands from your DCC throttle to the locomotive (through the DCC system).

A DCC system has three major parts.

  1. Throttle (user inputs his commands at the throttle)
  2. Command Station (converts user input to proper DCC format)
  3. Booster (converts Command Station output to a power level sufficient to run trains)

A DCC system manufacturer may choose to house any two or three of the above entities in a
single box.

Wiring Using the Atlas DCC Wiring Diagrams

This webpage will eventually contain DCC wiring diagrams for every Atlas HO and N scale layout that is in our layout planning books. Each DCC wiring diagram shown on this webpage replaces the DC wring (power packs, connectors/selectors, reverse loop controllers (Twin or Controller) shown in the DC layout wiring. You will still need the layout book for information on constructing the layout, track laying, etc. Unless you choose to have switch machines operated by your DCC system, you can wire switch machines the same as you would for a DC layout.

Although these layouts will operate properly when built as shown in the diagrams, there are a number of optional features that can be added to make layout operation more convenient.

Among these features are:

  1. DCC Auto Reversers to automate travel though a reverse loop
  2. DCC Circuit Breakers to automate cutting power on and off when there are short circuits. If you have wired your layout as shown in these diagrams, make sure that the circuit breaker you buy can be adjusted to work with common rail wiring
  3. DCC Controlled track switches. You must purchase enough stationary decoders (e.g., Atlas #344 Turnout Control Units) for all the switches to be operated from your DCC system.

Some Cautions

  1. Atlas recommends that you NEVER use on a DCC layout a locomotive that has no DCC decoder. If you operate an analog (no decoder) loco on a DCC layout, you are applying AC power to a DC motor. Applying AC power to a DC motor will cause the motor to overheat, and eventually the motor will be destroyed.
  2. To avoid possible expensive damage to your decoders and/or DCC system, Atlas strongly recommends that your DCC program track NOT be connected physically or electrically to any part of your layout.
  3. To avoid possible expensive damage to your decoders, DC power supply(s), and/or DCC system, Atlas strongly recommends that you wire your layout so that it is not possible to have DC power and DCC power present on the layout at the same time.

Suggestions for Wiring an Atlas Layout for DCC

  1. Each layout in an Atlas layout includes two important diagrams.
    • A track diagram that includes all track sections and all electrical connections to this track. The track connections are all marked, with each connection to the gapped rail labeled with a number. The corresponding common rail connection is labeled with the same number as the gapped rail followed by the letter “C”
    • A DC wiring diagram that includes one or more power packs, block power switches (#205 Connectors or #215 Selectors), reverse loop controllers (#210 Twins or #229 Controllers) if needed, and a number of #56 Switch Control Boxes (to operate remote switch machines
  2. The components shown in each DCC wiring diagram replace the components in the corresponding Atlas DC wiring diagram. Wiring the track for DCC is done the same way as it is done for DC. For example, the track terminal labeled “1” is connected to the terminal labeled “1” on the DCC wiring diagram. Similarly, track terminal “2” is connected to terminal “2” on the DCC wiring diagram, and so on.
  3. The #56 Switch Control Boxes are NOT shown in the DCC wiring diagrams, but you connect the Switch Control Boxes to Atlas remote switch machines in EXACTLY the same way shown in the Atlas DC wiring diagrams. The two wires from the AC or DC power supply used to operate the switch machines must be connected to the two screw terminals on the left or right side of each row of Atlas #56 Switch Control Boxes. The DCC wiring diagrams on this webpage all show the two
    terminals on the side of #56 control boxes connected to the two wires that run between the DCC system and the DCC system power supply. This wiring scheme works well if your DCC system power supply has a minimum output of at least two amps; however, if your power supply provides less than two amps, Atlas recommends that you power the switches with a 15-16 volt (AC) transformer that has a MINIMUM output of 2 to 3 amps. Connect the 15-16 VAC output of the transformer to the two screw terminals on the left or right side of each row of Atlas #56 Switch Control Boxes.
  4. Atlas recommends that you use a standard HO DC power pack to operate your Atlas turntable. You control the speed of rotation with the DC pack’s throttle and the direction of rotation with the pack’s direction switch.
  5. If you decide to replace your #205 Connectors with DCC circuit breakers, you might also decide to combine several adjacent DC blocks (blocks are called power districts in DCC) into one larger DCC power district. By combining several blocks, you will reduce the number of circuit breakers needed.

    All layouts in the Atlas books use common rail wiring, where all gaps are placed in just one rail. Not all DCC circuit breakers are capable of operating on a common rail layout. Make sure that you purchase a DCC circuit breaker that is compatible with common rail wiring.


N Scale Layout Books:
(Click on the book title and then the resulting layout (e.g., N-4) for which you want to see the DCC wiring diagram.)

Book #6 - Introduction to N Scale Model Railroading

Book #7 - Nine N Scale Railroads

HO Scale Layout Books:
(Click on the book title and then the resulting layout (e.g., HO-4) for which you want to see the DCC wiring diagram.)

Book #9 - The Atlas Beginners Guide to HO Model Railroading

Book #11 - Atlas HO Layouts for Every Space

Book #13 - Seven Step-by-Step HO Railroads

Book #14 - Atlas HO King-Size Layout Book


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