DCC main page

OK, while I think this falls into the FAQ category, I am going to put my "DCC introduction" here.

I want to take a different "tack" than how the subject is often explained. No need to dive into the internal technology, show waveforms, describe binary numbers or even CV's right now.

If you are new to DCC, my best advice is to FORGET everything you have heard about DCC, unless you have a friend that uses it successfully and can explain it to you.

This is not 10 years ago when the whole thing was unreliable, user unfriendly, and difficult to understand. If you have been given that impression, that person is not familiar with today's DCC, or is a battery junkie. That is what you will hear from people who don't understand it, or are anti-DCC.

Let's talk about what DCC can do for you:

• Use track power, less expensive than batteries, easier to install, and you can have remote control in tiny locos.
• True independent operation of multiple locos on the same track.
• Reduced wiring complexity, no need for "blocks" in 99% of layouts
• Products available from many different manufacturers, lots of options
• Many different throttles to use, and different levels of functions and complexity.
• Interfaces to computers and other softwares that allow automated running.
• Many different features but you do NOT have to use or learn them all, ever.

When someone will start using a new system, you normally talk "user-friendly", so I will try to look at it from a new person's perspective.

A new user wants to get up and running quickly, so the basic functions need to be simple, and more importantly, there need to be "default" settings to help this.

(I have to also set the stage with some basic assumptions, the locomotives have sound also.)

1. connecting the system to the track
2. connecting any components together
3. taking a new (out of the box) locomotive and with an "out of the box" decoder (receiver), identifying the locomotive's "name", how I have to refer to it
4. telling the system I want to control this locomotive
5. setting the direction of the locomotive
6. increasing or decreasing the speed of the locomotive.
7. Blowing the whistle/horn
8. Ringing the bell

1. customizing the locomotive name/identifier
2. having a "quick list" of 2-3 locomotives "saved" in the throttle
3. being able to switch between locomotives easily
4. customizing the momentum of the locomotive for more realistic operation
5. having a simple way to reproduce more sounds
6. easily running locomotives in multiple units or doubleheaded, or anywhere in a train.

I'm concerned with the details, so I have not put any DCC tutorials on my site. Look at the end of this page for links to sites to learn about DCC.

After a lot of research and reading lots of forums, I settled on the NCE system for a number of reasons, I really like the Pro throttle, and the computer interface. The throttle has very good menus and operation, and the computer interface allows me to use the JMRI and Loco CE software, or even run trains from my iPod or iPhone.

Their wireless throttles work exactly like the wired ones, and have full duplex communications to verify the commands have been received by the system.

Since my initial decision, I have experienced excellent service by NCE, the ability to contact an engineer at NCE for problems, and the great Yahoo forum for NCE. I'm still very happy years later.

DCC in general:

DCC uses a customized AC wave on the rails. The wave differs from the AC in your house in that the wave is square, not sinusoidal, and the frequency of the AC varies to provide the commands. This is very like FM radio.

DCC basically uses 4 components:

• A command station, which makes up a low voltage DCC signal which carries the COMMANDS 
• A throttle, which connects to the command station (wired and/or wireless) which has speed, direction, and function buttons for sound, lights, etc.
• A booster, which takes the low voltage DCC from the command station and BOOSTS it to higher voltage and amperage and puts it to the rails
• A Decoder in each locomotive, that picks up power and commands from the rails and controls the loco, lights, sounds, and optional extras. (not all decoders have sound in them)

DCC decoders for G scale

G scale has some special requirements.

• Higher current necessary for larger motors
• Higher voltage than the other scales
• Higher audio power output for sound decoders

Note: initially there were only decoders that controlled the motor and lights. Later there were decoders for sound only. Lately you can get a single decoder that has both motor control and sound in it.

I'm attempting to standardize on decoder capabilities as much as possible, and I want a system that has BEMF (Back ElectroMotive Force) that links to the sound decoder such that the locomotive's sound varies according to load, not just speed.

There are 2 ways to do this, one is an all-in-one decoder that combines sound and motor functions, and the other is a motor decoder that "communicates" the BEMF levels to a sound decoder. The only standardized way this is done is through the SUSI (Serial User Standard Interface).

Why higher current and how much:

It's pretty obvious that physically larger and heavier locomotives and trains will require more power to run. Power is a combination of voltage and current. Under heavy loads, some locos can draw many amps. 

There is a large variance, but you should assume that your loco can draw at least 3 amps continuously under load. 

The problem you will have if you are new to the hobby, you will have a hard time knowing what your locos draw. I would strongly recommend getting a DCC volt/amp meter, and actually MEASURE under load for yourself. There are so many variables, it's really a wide range.m

In addition, some decoder manufacturers rate their units optimistically, so you have to take that into consideration. In most cases I recommend a 5 amp decoder. There are some decoders that are rated lower that have no problems, like the QSI, which can be run at 3 amps solid all day. Likewise, the Digitrax decoders have the reputation of blowing up on loads way under their rating. 

Why higher voltage and how high:

This is a real problem for people that run prototypical speeds on more modern freight and passenger trains.  (explain top speed, nonlinearity of speed vs  voltage)

Important note: There are some DCC decoders out there that do not handle G scale voltages well at all. 

The "Quasinami" in the Bachmann 3 truck shay will freak out at somewhere around 20-21 volts.

There are several decoders from Germany, such as the Dietz DLE 2M, that wil not handle voltages over 18 volts. (It's actually more complex, where the 3 amp decoder cannot handle 2 amps and 18 volts at the same time, less amperage you might be able to run a higher voltage).This particular decoder is not really made by Dietz, but by Uhlenbrook.

The situation is probably just putting larger transistors on the HO decoders, and not considering the necessity of higher voltage requirements.

Sound power output:

You need at least one watt power, and some sound decoders have more, but remember that in the world of sound, 2 watts is NOT twice the volume as 1 watt. This is true because your perception of volume is not linear, but exponential. This means do not agonize between 1 watt and 2 watts, you might notice the difference between 1 watt and 5 watts. Getting a "large scale" decoder guarantees sufficient power output. 

Combination decoders

I'm going to list the decoders I have found here, and some of what I know:

QSI Solutions, by QSI Solutions, oem'ed from QSI Industries. New decoders that have motor control and sound. They are inexpensive (~$130), sound great, and make a plug and play decoder for Aristo locomotives. Easy and inexpensive. Thank you Tony!

Zimo, very high quality decoders. Initially quite expensive, but coming down in price to about $200. Huge selection of customization commands, but much weaker than the two sound "leaders" QSI and Phoenix.

Loksound Xl, ESU - from Germany, documentation sketchy and just a few US dealers, but recent 3.5 release adds a few more features. Big advantages are downloadable sounds, editing. Tricky to set up, but they recently have posted more US sounds. There are more becoming available through the US Massoth distributor.

I waited 6 years for the large scale Tusnami, by SoundTraxx - It looks as though they will never make these, too bad, they get great reviews on their HO ones. They made one OEM version for the Bachmann 3 truck shay, but no documentation, and it will often shut off on track voltages near 21 volts, which is necessary for large scale. Too bad.

SUSI motor decoders

Lenz makes wonderful decoders, but nothing with high enough current capability. They work well with D.I.E.T.Z. sound decoders. SUSI is a serial interface that communicates the engine load and status to the sound decoder.

The total cost of the 2 decoders is high, and there is little support and few American sounds on the sound decoders. Maybe this will grow in the future, but cost wise, it's probably never going to be competitive with the single combination decoders.

Sound only decoders 

Phoenix - Great sounds and wide range of locos. The 2k2 was very popular, recently replaced by the P9B decoder. It is expensive (~$220). Works on DC too, so it has been very popular. The newer P5 is aimed at DCC only and is less expensive (~$175), but seems to be obsoleted by the P8. In late 2009 and 2010, Phoenix deliveries have been poor, and they may obsolete yet another model. They can all be be downloaded with different sounds.

D.I.E.T.Z. - popular in Europe, has typical problems of limited support, poor documentation, limited number of US loco sounds.

Ullenbrock - The Uhlenbrock is the Deitz rebadged, as is the programmer.

DCC power supplies

Again, you need big power. I have a 10 amp system that puts out 24 volts RMS (you need a special meter to measure the RMS voltage of a DCC supply) I think I might have to go to 15 amps, since I intend to have MU diesels of 5 or 6 USA trains F units. The "worst" loco that would be MU'd is probably the USA trains GP9, which has been measured at 9 amps or so at full stall. The moral here, 5 amps is not enough, and 8 might be marginal.

Many DCC power supplies are just a big AC transformer. You should have a circuit breaker and probably a fuse also. No real magic here, but I find unregulated supplies have noticeable "sag" under load. If you want to run higher speeds, like passenger or modern freight, a regulated supply is best.

Regulated supplies are DC, and not all boosters (see below) will accept DC input. I am very happy with my NCE 10 amp system which does accept either AC or DC. 

I am using a regulated power supply and it's much better and helps get proper top speed.

DCC booster

This "boosts" the DCC signal to the current and voltage to the rails. It has 2 inputs and one output. You feed the DCC signal and the raw AC/DC power and it puts the DCC signal "on" the power and feeds it to the tracks. Finding high amperage boosters is hard. The easiest to find is the NCE 10 amp unit. I've found 15 and 25 amp units in Germany, but never seen or imported here from what I have seen.

Some boosters have an auto reverse mechanism built in. You need this when you have reversing loops. Basically it senses a short circuit when a loco spans 2 sections of track with opposite polarities (or phase if you wish). It then reverses the track feed.

You can also get auto reversing units to feed separate blocks. The DCC specialites PSX-AR is the first autoreverser that works well for large scale.

DCC controllers

Here's where there are strong opinions and preferences.

Some people want a simple wired cab control. Advantages are ease of use for newcomers, children, and those who don't want a complex device. Disadvantages are the wire can restrict your roaming around, connector problems, hard to control advanced functions. If it takes you a lot of button pressing to control a function, then it becomes a lot less fun.

Wireless simple cab control. Pretty much the same as a wired one, but wireless controls are more problematic because of the wireless range and response. There aren't too many simple ones. Many of the wireless units have slow response to commands, and are not as reliable, i.e. you blow the whistle, but it doesn't. This is because most wireless units use one-way communication. The controller never knows if the receiver really got the command. This can be disasterous when you really need to stop!
The big advantage is you have no tether, the disadvantages are battery life problems, reliability, slow response, limited range, sensitivity to interference.

Wireless advanced cab control. Well, if you are going wireless, why not make it easier. The NCE controller is a good choice.

Computer control - another option is to interface to the controller by computer. This can allow unattended operation, advanced block control, and/or train location detection.

Some computer control options also include the ability to have the computer act as a server to other computers running programs to control locomotives. KAM Industries is one example. They also have a product that lets you use a hand-held PDA as a wireless controller. One advantage of this is that the wireless communication used is a standard protocol already in widespread use, 802.ll, a.k.a. WiFi.

Books to read: (from an MLS forum thread)

Books:
Digital Command Control - the comprehensive guide to DCC (Paperback)
by Stan Ames (Author), Rutger Friberg (Author), Loizeaux. Edward (Author)
Publisher: Tried and True Trains (July 1998)
ISBN-10: 9185496499
ISBN-13: 978-9185496495

The DCC Guide (Paperback)
by Don Fiehmann (Author)
Publisher: Kalmbach Publishing Company (October 2007)
Language: English
ISBN-10: 0890246769
ISBN-13: 978-0890246764

DCC Made Easy ( Paperback )
by Lionel Strang ( Author )
Publisher: Kalmbach Publishing Company

DCC Projects & Applications ( Paperback )
by Mike Polsgrove ( author )
Publisher: Kalmbach Publishing Company 

Links to learn DCC:

Loy's Toys: http://www.loystoys.com/ Loy's Toys used to be a big retailer and specialized in DCC. Loy retired, but they are maintaining the site. Click on the "DCC Topics" in the main menu bar, on the top right. Good information.

Tony's Train Exchange - Tony's DCC Primer
http://www.tonystrainexchange.com/tonystips/dccprimer/index.htm

Matthias Manhart - Various DCC Decoder Installations
http://www.beathis.ch/lgb/umbau.html

Arnold's Train Web - Interesting DCC projects for largescale trains
http://atw.huebsch.at/index.htm 

DCC calculator:

http://www.unitconversion.org/numbers/base-10-to-base-2-conversion.html