Beginners Guide to DCC

DCC for Beginners
Practically everything nowadays is operated by a computer of some sort so does it seem that odd that your model trains could be run by one? Not really, but what could it do? Well just about anything you could imaging because quite realistically it can.

Great demonstration

You will most likely be familiar with the common 110/240v DC throttle controller. It is by far the most common arrangement to be found in a train set kit and without doubt the cheapest controller to be found in a hobbyshop. DCC on the other hand is something completely different and worlds apart in terms of operation and control.  Simply, DCC is Digital Command Control. It gives you many benefits over analogue control (DC) at a cost. You can run locomotives separately at the same time on the same line, dim the headlights, operate marker lights separately and operate sound. Sound good? Then read on.
DC throttle come in two variants, PWM (Pulse Width Modulation) or a transistor based DC controller. The PWM unit is superior to the basic variable voltage transistor base controller because of how it work. PWM sends a pulse of power across the rail which is better for slow train operations and it also tends to work better on dirty rails. The higher the voltage the better the locomotives will run. For example 12vdc PWM controller sends 12v pulses to the rail each with a gap in between the next pulse. As you move the throttle speed up the 12vdc pulses become shorter resulting in the locomotive running faster. In other words to the PWM controller sends 12v pulses half of the time resulting in the equivalent throttle setting of 6v
DC is simple and perfect for those of us that intent to run one train at a time with a limited main line or  even a small fiddle track. It’s also great way to get into the hobby however it does quickly reach its limits. If When you get more locomotives (you will absolutely get more, don’t kid yourself) your ability to use them and control them becomes more difficult. You will need to add isolation sections, you cannot easily automate track operations and so you’re ability to run realistic operation is limited.

DCC Signal Example
DC PWM Example 
You’re no doubt reading this and wondering what else can DCC do for me in order to sweeten the deal. Well, just about everything. You could fully automate your layout running to a timetable, add sensors that allow the system to know where your locomotives are at any given time, activate signals,  move turntabels, lights, special effects and the list goes on. Yes, DCC is worlds apart. The one gripe I had all those years ago was when I pulled a train into a station the lights would go out and I always wished that there was a way to keep them on.

DCC has been around for decades and I remember reading about it as a kid. All the big players in the game had glossy product catalogues that you would spend hours flipping through. Within a heavily worn Hornby brochure was the ZERO 1. Although I begged every store Santa that would listen, somehow my Zero 1 never quite made it into the sleigh. Still, my grandfather and I would play trains on his layout with the ever reliable Fleishmann DC controller that is still in production today. For DC controller, its fine control is second to none and I always envied the controller he had. If he was still around today I’m sure he would have been eager to play with DCC.
As with most standards in model railways the good people at the NMRA are custodians DCC protocol. This ensures that all manufacturers adhere to the standards set out by the NMRA and so that all the manufacturers products can be run together. Although this sounds like common sense model railways weren’t always like this. You can read more about the National Model Railroad Association (NMRA). The NMRA has trademarked the term DCC, so while the term Digital  Command Control is sometimes used to describe any digital model railway control system, strictly speaking it refers to NMRA DCC.

If you want to read more about the Standards
Let’s face it, In this day and age sophisticated consumer grade electronics run just about everything. Think about the technology involved in drones that can perform full autonomous flight with a circuit board no bigger than the profile of a playing card. The best devices are not powerful in terms of processing power but have intuitive and easy to user interfaces. This is of course what makes the Apple Iphone so popular in that although it’s truly powerful you don’t need masters to figure it out.

As a matter of fact, there are several apps for running DCC model trains.
So now that we’ve talked about what DCC can do, where do we start?
There are two main things which we need in order for you to use DCC on your layout:
1. A DCC system/controller
2. The Decoder (to be fitted into your locomotive)
At is most basic the DCC controller is an encoder that sends messages to decoders connected to your layout. As messages are transmitted from the encoder to decoders on your layout they listen to see if a message is addressed to them and act accordingly. Although this sounds a little complex it is seamless to the operator. Think of it like a letterbox and a postman. If the postman has something addressed to you he delivers the message and if not he drives on the next letterbox only to return the next day to repeat the process. This is similar, yet the post man comes several million times a day.

These are the questions you have to ask yourself before you decide to head own the DCC path.

Is DCC really what I want or need?

In other words can I achieve the same result with less or do I really need DCC

Is the cost associated with DCC justified? 

Only you can answer this but although the initial cost is higher than DC the benefits are clear. With a DCC Installation you will have more a enjoyable layout with less stress and more realistic operation. If you’re considering turntables, signaling, fiddle yards and industry you should absolutely consider a DCC system. Wiring a large layout is about the same as a DC layout so this is not a concern.

Will my old trains run on DCC?

Some older locomotives can absolutely be converted to DCC and a quick Google search might yield results fellow hobbyists documenting their success or failures. Do be careful when looking for bargains at a swap meet as some older/cheaper locomotives may not be suitable.

To convert to DCC you need three things.

 An 8pin or 21pin mechanism to accept a DCC decoder, or the ability to solder one in (The latter should be avoided if at all possible)

A good running locomotive is a must as a poor running locomotive will only run worse on DCC. You need a good electrical pickup system along with good running gear. Unless you’re emotionally invested, move on or upgrade. Lima engines were ok back in the day but they may not make great candidates for DCC.

A motor that is electrically isolated from the chassis or pickups. This is a real deal breaker and there is no workaround on this one.  

Which DCC System is for me?

Some entry level DCC systems may seem appealing but should be avoided. There are some exceptions like the z21 Start included with roco / fleischmann, however, the entry level Hornby DCC controllers are lacking many features. For example the z21 can be upgraded by purchasing a license that unlocks many of the features of the Z21 pro units. So, do your homework and don’t fall into the trap of buying something that you’ll have trouble trying to offload later on. A good DCC controller I going to cost from around $300 to $900 bu there are alternative if you’re handy with electronics.
There are of course open source solutions with a large following of members. DCC++ is going onto its 5th year and going strong. The outlay is not much and for around $20 you could have a DCC system better than most off the shelf solutions. If you are familiar with arduino or have someone good with electronics it’s worth a try. 

You can read more about it here

Above all check that the brand is NMRA Compatible. This allows locomotives with various NMRA compatible decoders to run on your layout. If you buy equipment that is not fully NMRA compliant you will likely have issues so don’t take the risk. 
You would expect that a long established brand such as Hornby could be trusted however they do not have a good track record with decoders or systems being 100% compatible with mainstream DCC products. Until this situation improves x you should be cautious when buying Hornby DCC products so do your homework. There are plenty of good products on the market so there is no need to be too concerned. 
Products should be certified or 100% compatible with the NMRA DCC standards and you should only support companies that make compatible products. In the past people have purchase products that are not fully compatible and as a result products would not work properly together. Some sound decoders had issues where a temporary short circuits caused the product not perform correctly and needed special modification to get it to work right.

Where Do I Start?

 These companies have off the shelf solutions DCC systems: Roco Lenz NCE Bachmann Marklin Digitrax Easy DCC Hornby (recommended with caution)

Open DCC

Where to from here?

There is a lot of information to digest however it’s not that hard to get your head around. As users we don’t need to understand what is happening within the electronics, we just need to know that our trains will run. If you are still wondering if DCC is for you I suggest you seek out a local club and have a chat with them about what works and does not. Most clubs run DCC as it’s the only way to run a layout with lots of locomotives running. Although DCC is not exactly plug-n-play it’s fairly close and for the most part is a very reliable and trustworthy system. I was personally not sure if I could justify the expense however after going DCC I don’t regret the spend,  I regret waiting.
DCC is more than just an expensive throttle and to help you get the most from the system we will take a look at what else is available to modelers. .

Sound Systems:

Sound can bring a layout to life add a new level of enjoyment and interest. There is nothing quite like a steam engine barking its way up a steep incline or the sound of a diesel engine starting up.  Some sound systems are compatible with DC layouts however I would recommend that you use sound equipped locomotives on DCC layouts because although compatible on DC layouts, it's fully accessible on DCC. All functions are available, from bell, whistle, horn, coupler crash, cooling fans - you name it. Your DCC controller should be able to cater for all sounds that are accessible on your locomotive.
Sound is not cheap but it is amazing and nothing compares. Sound can cost up to $300 for a sound decoder with speakers but there is no need to spend that much. $100 -/+ should get you a pretty good unit. The end results are amazing and Installing a sound decoder is similar to a decoder, but you need to install the speakers on top of the decoder so a locomotive with plenty of space is a must. If you plan on buying a second hand loco and installing sound make sure it is a modern loco with speaker provisions or space in the engine.

You may like to look at these companies which make quality DCC sound systems: QSI Soundtraxx LokSound

Sound in action


Sound Installation


DCC Accessories:

Accessory decoders are used to control all sorts of things but mostly, points, signals, light, or sound, etc. Most manufacturers produce DCC accessory decoders and the price does vary. Do shop around as some decoders will do the same job as another for half the price. Some commercial decoders are intended for a specific task such as PECO point motors or tortoise point motors and others are more flexible in what they control.
Most systems allow you to throw a point (activated from the accessory decoder) from your controller. There are devices allowing you to convert your control panel to issue these commands as well.  Opensource DCC is another option if you can find a supplier. 

Layout Compatibility

I’m sure you’ve heard this before “You need to make sure your layout wiring is DCC compatible” What does this even mean exactly? Put quite simply, Nothing. In reality DCC command station plugs straight into your layout in exactly the same place as your existing DC controller. Whilst this might not be true if we’re talking about a really large layout the vast majority can plug and play. Larger layout may need DCC boosters, but , as I said the vast majority need no additional work to start using DCC.  Why people over complicate DCC is beyond me.
Your track must be very clean and although this seems like a difficult task it is not. I recently wrote an article on track cleaning using transmission oil and I suggest you read that. You’ll never clean a rail any other way again and you’ll be pleased that you tried it. You can control trains separately so points do not need to have isolation functions as found with Hornby or Peco Insulfrogs, you can wire them up to allow the current to pass in all directions or purchase new points - a good simple one being the Peco Electrofrog, which is fully DCC compatible, and readily available. Of course you can also make your own points if you’re handy with a soldering iron

Ready to play now?
So, you’ve settled on a DCC system and you’ve taken it out of the box and started looking at it. Read the manual. Yes, read the manual as it will save you a stack of frustration. Once your locomotives are chipped and you’ve connected to your DCC controller to your layout you can power the system up.
Remember the default settings for a new locomotive is address number 3. You can tweak around with the decoder's settings to change its address, motor control, headlight functions etc. However, before you get too carried away, understand the basics first and ALWAYS refer to the user's manual for instructions.
Remember that DCC can be as simple or complicated as you like. Converting to DCC can be as simple as just two wires to start off with. Once you start using DCC and you start thinking about the options available you’ll be very busy planning new additions to your layout. Remember that clubs are only too happy to assist fellow enthusiasts and who knows, you might even make some new friends. DCC is a lot of fun when you get the hang of it, and it's easy to expand by purchasing a more advanced controller, or adding a booster pack to increase the number of trains operating on your layout (ordinary controllers allow around 3-4 HO/N scale trains to run at one time).
Last but not least, it's simply up to you on what choice system or decoder you choose. You choose the best for you. Check out its features and compatibility as well as its price to determine your end preference.

Arduino DCC++

There are very low cost options available to us. The DCC++ has been around for a long time now and is enjoyed by many. Whilst it might not for those with a limited understanding of electronics it is gaining popularity. You may even like to have a play with this system as the cost is only around $20
Happy Shunting
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