DCC FAQ
DCC FAQtttrains has provided this basic DCC FAQ to help you gather basic information about what NMRA DCC is. You might also want to check out our DCC Tips page. If you have further questions try the manufacturers site or email tttrains. Do you have further questions or topics you think should be added to this FAQ? Contact us with your ideas and comments.
An excellent resource for more information on DCC is Digital
Command Control - the comprehensive guide to DCC (Paperback)
by
Stan Ames,
Rutger Friberg, and
Loizeaux. Edward. This can be purchased on-line at
Amazon.com.
Please select from the following:
TTTrains' Home Page | Modeler's Corner | Large Scale | Links | World of DCC | TTTrains Train Shops | Lenz O Scale
DCC allows model railroaders to independently operate multiple locomotives, functions and accessories. Each item receives its commands through an addressed signal on the track. The packet information is interpreted by the receiver (decoder) and the command is carried out . Functions can include speed, sound, lighting , direction, movement.
Besides the huge advantage of independent control you gain with DCC, you gain the ability to customize the performance of each locomotive to the job and performance that you want on your layout. This is a huge step in control of model railroads. Each operator can have their locomotive perform the way they want. For example, we dislike jack rabbit starts and high speed, so we trim everything down to crawl speed with low top speeds, a great plus for our western narrow gauge railroad.
The NMRA has been working with manufacturers since 1992 to develop the next generation of train control. One of the big advantages of this is compatibility across manufacturers. Put another way, some only buy LGB, but if you put a Aristo Craft locomotive on the track it will run as you are not tied to a single manufacturer. DCC offers the same for multi train control systems.
The Standards and Recommended practices cover a whole range of features and the various manufacturers have selected the features they feel best meet their product line objectives and products.
Check out the NMRA site for the current set of NMRA DCC Standards and RPs..
There are two ways to get the approved Standards and Rp's.
(The above methods are the only distribution methods approved by the NMRA, who hold the copyright for these documents)
To get draft copies of preliminary Rp's, or join the WG contact:
Decoders are the electronics that go within each locomotive. Decoders operate the locomotives motor and can control the locomotives functions. You can currently purchase decoders with anywhere from only a single light function to one with 8 functions. The more functions the more items you can control. That introduces the first decision you must make. How many functions do you want? If your command station can only send one function and you have decoders with 8, that command station can still only control a single function.
Decoders also have various motor control features. Most of the older entry level ones hadspeed and direction, while the more advanced ones have, for example, acceleration, deceleration, consist control, and motor back emf control.
Modern decoders offer a big selection of drives, special lighting effects. Drives can include, but don't always, silent drive, selection -drive, advanced generations of load compensation, etc. And there always a broad selection of drop in boards from a variety of manufacturers.
The advice, is to shop for decoders as needed per locomotive. We have see people purchase 20 decoders at a clip and then only install 5, leaving 15 on the shelf becoming obsolete in 3 years. The generation of decoders is around three years, so having left overs is OK, but a bit frustrating when new features and lower prices have just been announced as you settle in for an install session using older decoders from your stash on the shelf.
Back Emf control is very useful in a garden railroad environment where you have a lot of grades or for delicate switching. With Emf control, you can control the train so that it crawls at a very slow constant speed (a must for switching operations) or if you like have the locomotive operate up and down hills at a constant speed. (very important for those who desire to watch their trains while sipping lemonade on the back porch).
Think of Back Emf as somewhat like speed control in your car. The decoder constantly determines the needs of the motor and adjusts it accordingly. You can set the speed at a level and the train will operate at that speed independent of load or grade. (until wheel slip) If you have few grades and like to operate at high speeds it is not worth the expense, but if you like slow operation or have a lot of grades, it is well worth the expense.
Command stations create commands from the throttle and pass it on to the power stations.
Command stations are the limiting factor of software. It other words if your command station supports only 2 digit addresses, your decoders can only run 2 digit, even though the decoder is capable of four.
Command stations vary from manufacturer to manufacturer, offering different levels of capability. Make sure you understand what you are getting, so you will not be disappointed or overwhelmed with capabilities.
Naturally, there are a variety of prices depending on the features. Our garden layout is currently controlled by a Lenz Digital Plus system, which has multi unit control up to 256 simultaneously operating It is quite doubtful we ever run that many- we'd have to sell the house to have that many locomotives. It also can control 256 switch machines.
Now with decoder and command station in hand you will need a power station. The more power, the more trains you can run at the same time. (note: some command stations, such as LGB's have a built in power station) The power station sits between your transformer and the rails and combines the digital signal with electrical power.
We have used a large variety of systems and have blended them together for a variety of purposes. The needs of our HO, Large Scale, and N-scale layouts differ dramatically. We have had a good time blending the systems.
We have operated the garden railway with North Coast Power Stations, Lenz Command Station , System One Power Stations, Aristo (modified) radio control, and a variety of decoders. When kids are over we also use LH90s Handhelds as they are the best for kids with the rotary knob and easy stack selection. We have also used the Bachmann E-Z command for demonstration purposes to show that it can operate a truly large layout when connected to power stations.
Our son started with a Digitrax Challenger system. We are truly an eclectic bunch!
Today tttrains Inc. manages the Lenz Agency of North America so as might be expected most of the railroads are controlled by Digital Plus by Lenz NMRA DCC systems.
Inside we operate a track cleaner at times to remove the dust and keep the tracks clean. We believe in using cleaners to wipe the track rather than abrasives.
Outside dirt is more of a problem (real dirt). Stainless Steel track is best if you want to avoid cleaning track but you still need to clean the locomotives wheels and pickups from time to time. To avoid dirty track problems entirely, we currently use a Hybrid Drive approach using USP Gold Maxi Decoders, which very nicely take the locomotive over dirty sections of track while maintaining complete control. Our son has also installed Gold mini decoders with Power-1 modules in N scale Steam locomotives.
From Dick Lord we received this advice: "I am a hardware engineer with over 35 years of experience, with an MSEE and a BS in physics. I know my way around electrons. I have also been heavily involved in the DCC standards effort from the beginning. I believe that I am qualified to make the following statements."
Accessory decoders are going through a large transition at present. Some decoders allow you to control 4 turnouts from one decoder. Most accessory decoders can be used on different manufacturers systems.
For most locomotives, you can install decoders without effecting the Warranty of the locomotive. In large Scale and N scale you may need to alter the basic mechanism in order to get the motor isolated from the frame. Almost all modern locomotives do not have this problem. A DCC ready locomotive has already isolated the motor from the track and is much easier for installing decoders.
More and more dealers are beginning to offer installations, however, this can be pricey, so make sure you have a full understanding of the services that are included. Some dealers offer excellent service some offer slap dash service. The best advice is to learn to install yourself or use someone who comes with recommendations.
As more and more locomotive manufacturers include the NMRA socket, plugging in decoders is easier and easier. Make sure you understand if a locomotive has a NMRA 8-pin socket or not. We have seen installers charge $24 for just removing the shell and plugging a decoder in. This, we feel, is taking advantage of the novice.
Copyright 1993-2007 by Tried & True Trains
Inc.
This page is written and maintained by: Stan Ames
For more information contact Debbie Ames,
President tttrains