What is DCC?

DCC or Digital Command Control is an electronic means of controlling your trains and accessories.  By fitting a DCC Decoder in each of your locomotives and assigning each one a unique address or identity number and using a specially designed DCC Controller you can drive as many trains on your layout that your chosen system and power supply will handle.  You can have several locomotives on the same piece of track and you can control each of them independently.

There are several components that make up the DCC system, the controller and power supply, locomotive decoders, accessory decoders and the wiring to the track and accessories.

As with any model railway layout you will need a power supply and a controller.  Both are similar to look at to a conventional analogue controller and power unit.  The difference lies in how they tell the loco what to do.  In a simple analogue controller, turning the regulator increases or decreases the voltage to the track, this in turns raises or lowers the speed of the loco on that section of track.  When the controllers are at zero the track voltage is 0 volts.  On a DCC system the track voltage is a constant voltage (normally 16 Volts AC but there are some variations on this).  The controller overlays this voltage with a signal that tells the loco what to do and this signal can only be read by the loco which corresponds with the address sent by the controller.   Most systems have uprated power supplies for those who wish to run more than 3 or 4 trains at once.

Locomotive decoders convert the digital signal into commands for speed and direction, and also allow you to control other functions such as light and sound when fitted.

Accessory decoders allow users to change points, lower crossing gates, sound alarms, operate cranes, load coal, empty coal, operate turntables and perform any other function you now do with an array of buttons.

Wiring to the track is the most important part of any model railway layout, digital or analogue, as this carries the current from the controller to the loco.  With DCC all you need is a pair of wires from your controller to the track.  All sections of the track are fed from these two wires, no switches and no worries about having two trains on the same piece of track.

Are all manufacturer's products compatible?  Yes and no, if the product is showing the NMRA DCC symbol then by and large those components can be 'mixed and matched' with another make, there have been some compatibility issues but these are few and far between and provided you stick with any of the main manufacturers there should be no problems. It means you could use a Gaugemaster Prodigy controller with a Lenz decoder fitted into a Hornby loco running on Peco track. The NMRA standard means that there are common methods of control.

You can even use a computer with DCC.  Some DCC Systems will allow the use of a computer to send information to the decoder and this would enable you to program a sequence to start and stop trains when you want the layout to run by itself.  Provided the software was available for your system then the trains would obey the signals and rules of operation that you set for your railway.

How do I choose which DCC system to buy?

The first thing to decide is what you want to control from your controller and whether you want a hand-held or a conventional style control panel.