A Guide TO Dcc Page 5 A Guide to DCC

5 4 Designing for Growth As layouts grow there are a couple of options. If you know you will be growing the layout, it is often wise to go ahead and invest in a more powerful system up front. Providing breakers and creating protected sections of track will keep the equipment safe. As the layout grows, or if more locos are added to the stable, it is possible a large booster will get tapped out. In these cases, your layout can be set up with multiple boosters. This is called creating power districts, where different boosters will power different parts of the layout. Within each power district, breakers will protect different sections of track. Note that both rails will have to be gapped between power districts since the power is coming from different sources. Also, the boosters will have to be in phase at the gap. If they are out of phase, a crossing locomotive or car will get the full wrath of short circuit current from both boosters! Always check before running something across the gaps. If the voltage between adjacent rails is nearly zero, then you know the rails are in phase. One thing to keep in mind is that boosters of different manufacturers may use power electronics that are different in design from each other. This can create some phase shifts in the power going to the layout, creating serious problems at the faps between power districts. It is best to have all your boosters from the same manufacturer, or at least confirm compatibility. Note that you only need one command station on any DCC layout. All the boosters will get their information from the one command station. With abundant, reliable power, you will have no problem running any and all the trains you want on your layout. The key is to make sure your power system matches your need. Understanding these elements will help you make the right decisions to make your layout a success! Find a system that will meet your needs and a little bit more. You dont want to be running at maximum capacity on the booster all the time. Not only does it not allow much margin for it to trip, but there will be times where extra surges of power are needed. For instance, many sound decoders have capacitors on board that need to be charged when the layout is turned on. Often, this inrush current will be several times that of normal power. Having a booster system that can handle the inflow is good. A rule of thumb is to allow a half of an amp per loco on the layout. DECODERS Decoder Types and Their Features Most DCC decoders are considered mobile decoders. In other words, these are decoders that take the power and signal off the track and translate commands into outputs that control the motor and lighting. Mobile decoders can be broken down into some basic types: Basic Decoders - These provide only basic motor control and maybe 2-4 lighting outputs. They are a great option for converting older, pre-DCC locomotives that you may want to run occasionally on DCC. They are typically cost effective and easy to wire in. Most modern basic decoders come with back EMF motor control to provide excellent speed control, although there are some that are without Back EMF (Electro-Motive Force). It is often very easy and relatively inexpensive to replace a non- BEMF decoder with one that has BEMF control, providing much improved slow speed operation. Sound Decoders - As interest in operating trains through DCC developed, interest in having the decoder provide sound as well as motor and lighting controls developed as well. Most sound decoders offer accurate sounds reflecting actual prototypes. Many of these decoders are not much larger than a basic decoder, however they tend to cost quite a bit more. There are decoders where the speakers for the sound are included on the board. In most cases, however they are separate, and often not included with the decoder. Installing or retrofitting a model with sound can be challenging, especially in a model that has limited space. However, the realism provided by the addition of sound is often desired by many modelers. Matched Basic Decoders - In some cases, modelers have installed sound decoders in locomotives, and would like to run non-sound equipped locos with them. However, often installing a basic decoder in a matched locomotive will result in the locomotive not running the same. Some manufacturers offer basic decoders with programming and functionality that exactly matches their sound decoder offerings. This makes speed matching and consisting much easier. Function Only/Sound Only Decoders - As the name implies, these are decoders without motor controls or only with sound. Function only decoders can be very useful if, for example, you want more lighting functions provided than the motor decoder provides. Function only decoders can also be used in rolling stock such as passenger cars or cabooses to turn on and off marker lights or interior lighting. Sound only decoders provide the option of adding sound to a locomotive that already has a motor decoder. Stationary decoders are, as the name implies, used to operate devices on the layout via the DCC system. Most commonly, stationary decoders will operate switches, and there are different types of decoders for different types of switch machines, such as twin coils or slow motion motors. Refer to the section on stationary decoders to understand these more fully. Configuration Variables or CVs - Every decoder has configuration variables, CVs that are used to program their functionality. At the most basic level, there are CVs to define the decoder ad- dress, most usually programmed as the locomotive number, its maximum speed, starting volt- age, acceleration rates and de- celeration rates. Additional CVs are generally provided to control everything from how lighting is controlled to the volume of the sound. Some even have spe- cial effects such as reverb and Easy-to-install decoders are available for most N Scale locos and cars.

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