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DCC Conversions

Introduction to Digital Command and Control (DCC) conversions

Digital Command and Control (DCC) revolutionizes the control of trains on a layout, offering enhanced low-speed running and realistic operation. Multiple trains can share the same track section, each being controlled independently in any direction and speed. The lights remain consistently bright even when the train is stationary and can be controlled individually. DCC brings numerous improvements to layouts, which explains its growing popularity in this hobby.

DCC-ready trains can be converted by plugging a DCC decoder into the NEM decoder interface, whilst older non-DCC-ready trains require the decoder to be hardwired. Fitting a DCC decoder can be challenging for some hobbyists, especially with N scale and some older OO scale locomotives due to the limited space and complex layout of the chassis. Therefore, careful decoder selection is crucial.

Mark’s Trains offers a customized DCC conversion service, where you can choose your preferred brand of decoder or rely on our recommendation for a high-quality decoder suitable for your needs. All conversions include thorough testing on a test track and programming the decoder to ensure optimal smooth and slow-speed operation.

What is the difference between DC and DCC?

DC (Direct Current) and DCC (Digital Command Control) are two ways to control model trains/locomotives. DCC operation offers several advantages over DC operation:

  • Multiple Train Control: With DCC, you can run multiple trains independently on the same track. With DC, all locomotives on a powered section move at the same speed and direction.
  • More Realistic Operation: DCC decoders can be programmed to simulate realistic locomotive behaviour like slow starts, stops, and inertia coasting. DC relies on manually controlling the throttle to achieve a similar effect, but it’s less precise.
  • Lighting and Sound Effects: DCC allows individual control of lighting and sound features on each locomotive. DC offers limited lighting control and no sound.
  • Simplified Wiring: DCC typically uses only two wires for the entire layout, while DC requires more complex wiring with block sections and switches to control multiple trains.
  • Easier Layout Expansion: Adding new locomotives or modifying your layout is much simpler with DCC because you don’t need to re-wire block sections and expand switch panels.

Here’s a table summarizing the key points:

Feature DCC DC
Multiple Train Control Yes No
Realistic Operation Yes (programmable) Limited (manual control)
Lighting/Sound Individually controlled Limited lighting, no sound
Wiring Complexity Simpler (2 wires) More complex (block sections)
Layout Expansion Easier Requires rewiring block sections

Overall, DCC offers much more flexibility, control, and realism for model train enthusiasts. However, DC systems are generally less expensive and may be suitable for simpler layouts with a single train.

What is a DCC conversion?

Digital conversion of model railway locomotives is the process of converting an analogue locomotive to a digitally controlled locomotive. This allows the locomotive to be controlled by a digital controller, which offers several advantages over analogue controllers, including:


  • More precise speed control. Digital controllers can control the speed of a locomotive in much finer increments than analogue controllers, giving you more precise control over the movement of your trains.
  • Multiple locomotive control. Digital controllers can control multiple locomotives simultaneously, allowing you to create complex train movements with ease.
  • Sound and lighting control. Digital controllers can control the sound and lighting functions of your locomotives, giving you even more control over the look and feel of your layout.

How is a conversion undertaken?

To convert an analogue locomotive to digital control you will need a digital decoder. A decoder is a small electronic device that plugs into the locomotive and converts the digital signals from the controller into analogue signals that the locomotive can understand.

There are many different decoders available on the market, so it is important to choose one that is compatible with your locomotive and your digital controller. Once you have chosen a decoder, you will need to install it in the locomotive. This process can be a little daunting and there are many resources available to help you, including online tutorials, books, and videos on the internet. However, our experienced team can undertake this work for you.

Before installation of the decoder it is advised to give the locomotive a good run-in on DC (30 – 60 minutes) so that the drive gears are free moving and motor brushes are bedded in sufficiently. This is also a good time to see if there are any running issues such as poor power pickup which must be resolved before the conversion takes place. This is because digital control relies on a modulated signal being carried by the track voltage, and any noise caused by poor and intermittant power supply corrupts the signal to the decoder preventing correct commands being received by the decoder. As an example, a locomotive stutters a little on DC control and this effect would be amplified on DCC, meaning the locomotive stops and starts quite often or struggles to get going.

Once the decoder is installed, you will need to program it. This process involves setting the decoder’s parameters, such as the locomotive’s speed, acceleration, braking, and motor settings. Once the decoder is programmed, your locomotive is ready to be used with a digital controller. Simply place the locomotive onto the track and connect the DCC controller to the track. You should now be able to control the locomotive using the controller, in most cases, the locomotive’s decoder address will be set to the factory default of 3 unless this has been programmed with your desired address.

Digital conversion of model railway locomotives can be quite a daunting task if you are new to digital control, but it is a rewarding one. With a little effort, you can convert your analogue locomotives to digital control and enjoy all the benefits that digital control has to offer.

Here are some additional tips for digital conversion of model railway locomotives:

  • Do your research. Before you start, it is important to do your research and learn as much as you can about digital conversion. There are many resources available online and in libraries.
  • Be patient. Digital conversion can be a time-consuming process. Be patient and take your time, and you will be rewarded with a successful conversion.
  • Don’t be afraid to ask for help. If you get stuck, don’t be afraid to ask for help from a more experienced modeller. There are many online forums and local model clubs where you can find plenty of help.

Other considerations

To further enhance the performance of your DCC-converted models, you could consider installing a stay-alive circuit to your decoder. This eliminates the frustration of your model stopping at certain points or rail joints due to poor power pick-up in these areas. This issue is most common with sound-fitted short wheel-based models, where the sound stops and resets (engine restarts). Mark’s Trains provides a retrofit service to install a stay-alive circuit to your existing decoder or offer it as an additional option during the conversion process. This service’s feasibility depends on your decoder’s compatibility, and an inspection may be necessary before commencing the work.

In addition to DCC conversions, Mark’s Trains offers a range of other services such as cab or interior detailing, directional and prototypical lighting, weathering, and servicing (recommended for used models) to keep your models in good working order and to ensure a reliable digital conversion. Mark’s Trains also offers a motor rewind and re-magnetisation service.

Struggling to convert your models?

If the thought of converting your locomotives to digital control sounds too complex, why not let our team of experts undertake this work for you. You’ll be safe in the knowledge that the conversion will be completed to a professional standard.

If you are interested in booking a conversion or to discuss your requirements click on the ‘Book now’ button below.