Why should we adopt DCC control of NTRAK and T-TRAK layouts? There are several reasons:
Run Your Train, Not Your Track
This Digitrax advertising slogan is exactly right, and that is what we primarily do on NTRAK and T-TRAK layouts — run trains. With DC operation, whether using the old NTRAK throttles, the current Aristo wireless throttles or just a standard DC power pack you are essentially running your trains by adjusting the voltage to the track. All trains under control of the throttle are receiving the same voltage with the same polarity and running in the same direction. With NTRAK throttles you give up control of your train to another throttle as you enter the next electrical block. With Aristo throttles you must change channels as you enter the next electrical block. In either case the voltage on the track is probably different from your current voltage with a resulting surge or slowdown of your train as it cross the block boundary.
DCC provides something better. With DCC there is constant voltage on the track and you are controlling your train through signals passed from your throttle through the Command Station and Booster(s) to a computer chip (decoder) in your locomotive which controls how much voltage the motor will receive and its direction. Speed and direction is unique to your locomotive, and independent from all other locomotives. Direction is controlled by the throttle and is independent of which direction the locomotive is placed on the track; forward is forward and backward is backward.
Multiple locomotives can be MUed or consisted together to be controlled as a single unit from one throttle, just like the prototype does. By adjusting the decoder parameters (Configuration Variables) you can fine tune locomotive operation so each locomotive in the consist runs at the same speed, even locomotives of different types and from different manufacturers. Locomotives can be added to or deleted from the consist at any time, even while the train is running.
Multiple trains can be operated close together without regard to switching track power. All tracks are powered so multiple actions can take place at the same time, such as switching and make-up of trains in a yard.
Electrical blocks (called districts) in a DCC system are provided for reasons other than locomotive control. The engineer of a DCC–controlled train need not know the location of electrical district boundaries as they are transparent to operation of the train.
Independent Control of Lights and Sound
Since decoders are essentially computer chips they can be programmed (to the extent a particular decoder is equipped with the capability) to provide many different lighting and sound effects. As well as directional headlight and rear lights some lighting effects include ditch lights, Rule 17 headlights, MARS-type lights, beacons, strobe lights, etc. All are under control of the function buttons of the throttle running the locomotive.
These lighting effects can also be added to rolling stock using a function-only decoder, available from several manufacturers. These decoders do not have control for a motor, but enable lighting effects in dummy locomotives, passenger cars, cabooses, etc.
Prototype realistic sound can be added to locomotives through decoders designed for sound. Sound-equipped N scale locomotives are available, and sound decoders have been available for several years for custom installations. Some sound decoders are sold with sounds for a specific prototype locomotive while others offer a custom sound download feature. In all cases separate adjustment of each sound feature is provided to enable customization — volume and effects. Prototypical operation of a locomotive's horn/whistle and bell becomes possible.
Walkaround Control
Most DCC systems provide for walkaround control which allows you to walk with your train around the layout, staying where the action is. Walkaround throttles can be tethered or wireless.
Tethered throttles must be plugged into a throttle bus to control the train, but they can be unplugged and plugged into another location on the bus as the train proceeds. The train will continue to run at the speed and in the direction it is going while the throttle is unplugged.
Wireless throttles transmit to a receiver using either Infra-Red (IR) like a TV remote control or radio, and provide complete flexibility for running your train. For NTRAK and T-TRAK layouts radio throttles are preferred since they do not have the line-of-sight restrictions of IR.
Accessory Decoders, Signals and Other Functions
These are specialized decoders used to operate turnout machines and other electrical accessories from the DCC throttle. This allows an engineer to control the route his train will take from his throttle without having to manually throw a turnout.
DCC-based signaling is now available from several suppliers, and is now seen on NTRAK modules. These signaling systems can also interface to a computer for dispatching purposes.
Accessory decoders and signaling so far have seen limited use on NTRAK and T-TRAK layouts, but this use is rapidly increasing.
Constant Track Power
With DC control the speed of the locomotive(s) is proportional to the voltage on the track. Slow speed means low voltage in the track which limits the ability to overcome dirt and other wheel-to-rail contact contamination. This results in inconsistent speed and operation. If a DC track is run in the same direction all the time it will also encounter a greater build-up of dirt and other contaminants in one rail than the other.
DCC provides a constant higher-level track voltage, nominal 12 volts for N scale, which helps with the dirt problem. DCC is also an alternating current which means each rail sees a constantly changing polarity. This results in a more even distribution of dirt and contaminants, and results in improved control especially at slow speeds, but it does not obviate the need to start with clean track.
The constant track voltage also provides for the operation of accessory decoders, turnouts, lighting and other accessories independent of train control.
Operations
Since your are running trains rather than the track, multiple trains can be run at the same time, even on the same track. This means more trains per NTRAK or T-TRAK track, and more for spectators to see and stay at your layout during a show. It also means that various forms of prototype operations can be carried out, from simple card order operation to timetable operation to a fully dispatched railroad.
Some DCC manufacturers have integrated a fast clock into their system where the fast time can be viewed on the throttle display or on a clock display that plugs into the DCC system. When desired this function can be used to enhance a prototype operating session.
DCC Architecture
The National Model Railroad Association (NMRA) established an open architecture for DCC and maintains the Standards and Recommended Practices for DCC. These Standards and RPs are followed by all DCC manufacturers. The standards set the interoperability point as the track, which means that any DCC system from any DCC manufacturer will work with any manufacturer's decoder.
This does not mean that every DCC component will work with every other component from any manufacturer — for example a throttle from one manufacturer may not work with the command station from another manufacturer, although most command stations can control boosters from other manufacturers. It does ensure interoperability at the track between the booster and decoder — decoders will understand the commands received from any booster.
You Don't Have to be an Electrical Engineer to Use DCC
The fact that DCC involves electronics and computer chips tends to intimidate many folks who are not electrical engineers. But computers have electronics and chips yet most people use computers. Many items — your stereo, television, cell phone, smart phone, tablet computer, microwave, etc. — also use electronics and computer chips but most people use them. DCC is not difficult nor complicated.
You can purchase locomotives with decoders installed. You can purchase locomotives ready for a decoder to be installed, either through a plug connector or by simple replacement of a circuit board in the locomotive. Either way provides an easy way to start — most locomotives available today from Athearn, Atlas, Bachmann, Con-Cor, Fox Valley, InterMountain, Kato, Micro-Trains and Walthers/Life-Like are either equipped with a decoder or capable of easy decoder installation.
Getting started with DCC on an NTRAK or T-TRAK layout is also not difficult. Simply connect the Booster track output to one of the NTRAK track power feeds and start running. Use this to get experience then plan what you need to expand DCC on your layout according to what your club desires. A great deal of information on doing this can be found on other pages in this web site.
Appoint a Digital Master for the club. This person, usually someone who is technically knowledgeable or who wants to learn, learns the nuts and bolts of DCC at the next level, and leads the club in planning for DCC and in setting up and operating NTRAK and T-TRAK layouts. There is also a great deal of information on this web site targeted specifically at the Digital Master. |
The number of trains that can be operated by a Booster depends on the current output of the Booster and the total current draw of the locomotives and lighted cars in the train. Booster are available with different current outputs, anywhere from 2.5A to 5A to 8A to 10A, depending on the manufacturer.
The is no formal standard for a particular DCC system for NTRAK or T-TRAK, but there is a "de facto" standard — Digitrax. Some 88% of NTRAK clubs operating with DCC have chosen the Digitrax system. While any club is free to chose whatever system it feels will best meet its needs the overall preponderance of Digitrax systems means that almost all major NTRAK and T-TRAK layouts at conventions and shows will be Digitrax controlled.