How DCC works

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Summary: Digital Command Control works by combining the output of a power supply with digital instructions telling the locomotives and other accessories what to do, applied directly onto the track.


Multifunction Decoders, which are in fact small computers (or micro controllers), respond to instructions addressed to them. The decoders are installed in locomotives, or are larger stationary devices that can control signals and switch machines.

The important concept is that a DCC booster is applying a pure digital signal onto the track. There are no high frequency carriers or audio tones present on the track, as were often employed by earlier analog command control systems. Many opinions expressed regarding how DCC works are often rooted in Analog, thus the DCC concepts are being forced to comply with older analog methods.

The digital signal contains not only the address and the instructions, but also supplies the power needed. The data is carried by changing the width of the pulse while the amplitude remains constant.

Schema DCC en

The Digital Command Control System

  1. Digital Only
  2. Data and Power carried by the same signal
  3. No carriers, tones or high frequency signals
  4. Digital data is not superimposed on a DC voltage
  5. Not a modified Alternating Current waveform

Read more to learn about Digital Command Control and how it can enhance your layout.

See Also