Digital Command Control or DCC Explained
The traditional method of controlling power to model trains has been Analog control which monitors and provides current (AC or DC) to a section of track. However if you’re close to my age, mid-thirties, you have the option of getting more granular control in your electrical needs by using Digital Command Control or DCC setups. DCC allows you to operate multiple locomotives or even their ancillary functions like lights and whistles with a single control unit as opposed to controlling power flow to a single unit of track. To get this kind of control each locomotive is outfitted with a decoder that intercepts signals in the track.
DCC throttle unit
Decoders vary based on the number of instructions they can accommodate such speed, direction, lights, etc… One thing to bear in mind is that if your locomotive decoder can support 6 simultaneous instruction but your digital command controller can only control one function at a time then your decoder can effectively only control one function at a time. Some decoders are very simple and only control direction and speed but some also provider more advanced functionality such as motor back electromotive force, or motor back emf for short.
What is motor back emf? Motor back emf allows you to set a specific speed and regardless of track grade or train car load the locomotive will attempt to maintain that speed. So if you have an elevation in your track you shouldn’t notice a difference in speed regardless of whether the train is on the incline or on a flat section of track.
Some of the more whimsical features of DCC come in the sound control. Apart from the standard whistle effect you could have access to air pump, dynamo, coupler action, brake, and even diesel engine “rumble”, pretty neat! You can buy these sound systems by themselves or you can buy locomotives with these sound features built in.
Another nicety of DCC is that since each locomotive is controlled versus the section of track you no longer have to segment your track to support control of multiple locomotives. DCC also allows more of a “sit back and relax” mode of operating your trains since you aren’t constantly toggling switches depending on which segment of track a locomotive happens to be on (however some people may like the constant control as it makes them feel more like a true conductor, to each his or her own.) The wiring of a DCC track is also a lot less complex than that of a segmented analog track. DCC also ensures a more consistent signal regardless of the the distance from the locomotive to the control unit.
Despite all the advantages to digital command control there are some trade offs, mostly in the wallet area. DCC controllers are more expensive, and each locomotive will need to be fitted with a decoder, another $30+ dollars, and the decoder will have to be installed which could run you anywhere from $10 to $20. You can see how the locomotive decoder costs can really add up if you have several to upgrade, also not all locomotives are upgradeable.
If somebody was just getting started in model railroading and they were not buying a kit that included an analog control setup I would definitely encourage them to go the DCC route!