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Below we try and answer some of the most FAQ's About DCC.

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Digital Command Control FAQ

1. HOW DOES DIGITAL WORK AND CAN TRAINS RUN IN OPPOSITE DIRECTIONS ON THE SAME TRACK.

• The easiest way to think of Digital is to think of it as a full scale electrified railway. On an electrified railway the power is constantly 'on' and the various drivers start and stop their own trains using control equipment on board the train.
• The Digital decoder that is fitted to locos working on Digital is the 'control equipment' on board the train and instead of the driver actually being on board he is sending signals along the rails to the loco (it could just as well be by radio control as is done in some full scale yards but would be less effective).
• The trains run in whatever direction you want them to run. If you set, say, a steam engine to run chimney-first and then lift it and turn it end for end on the same piece of track it will move off chimney-first again in the opposite direction.
• Short circuits have to be avoided as in DC control. A reverse loop without any modification would cause a short circuit exactly as in conventional DC control. You can have 'reverse loops' with insulated rail joiners etc. as in 'conventional control', but in fact, you can, using the Lenz LK100 or Digitrax AR-1 Units, send a train round the loop without stopping and without any physical switching.

2. DO YOU NEED SPECIAL TRACK OR SPECIALLY DESIGNED LAYOUTS. WHAT MAKE OF POINTS DO YOU USE.

• You do not need special track. Clearly, the locos be they DC or DCC pick up their power (DC) or power and information (DCC) from the track and it is irrelevant whether you use 'dead frogs' or 'live frogs'.
• All that is required from 2-rail track is that no short circuits occur in any situation.
• Digital control can be immediately applied to any existing 2-rail DC layout without any modification to the layout. The only difference from a layout designed from the start for digital control is that there are not nearly as many switches and isolated sections in the 'Digital Layout' (More Power Feeds Maybe needed).
• There are no 'Digital Points'. In some situations non-isolating points can avoid a little bit of extra wiring, but for sidings, isolating points can be useful on any layout. The points requiring less wiring for Digital control are those with 'changeable polarity frogs' such as Peco 'Insulfrog' or 'Electrofrog' or any points can be used as they would for DC

3. WHAT IS THE BEST DIGITAL SYSTEM.

• There is no answer Straight to this question, as its down to personal choice, and what system will suit your needs. Anyone using conventional 2 rail DC should only buy an NMRA-compatible system (That's all that we sell!). Clearly buying a system with a long proved track record is going to be an advantage but having said that, we have not yet come across any 'dud' systems, just some have better features or offer more for your £ You have to ask yourself what you want from DCC.

4. WHY ARE THERE SUCH DIFFERENCES IN PRICE.

• Generally speaking you get what you pay for in the way of features and functions. In fact comparing like with like among NMRA-compatible systems there are not really significant price variations within a given specification. There are now Only 2 general types of systems available:-
• 4.1 . Entry level systems controlling up to about 10 addresses such as Bachmann EZ Command, 100 addresses such as Lenz compact, or 9999 Address with Limited Ampere output Gaugemaster Prodigy, Digitrax Zephyr & NCE Power Cab. If you are on a budget and simply want to have control over that number of locos on the same track, or just want to try DCC without too much expenditure then perhaps entry level is what you want. Your locos will still run with a more up-market system without modification. The range of further options such as programming features other than loco address into loco decoders is however, sometimes limited as are double headers. Entry level systems cost from about £50.00-£225.00.
• 4.2 Full feature systems such as Lenz Set 90 & 100, NCE Pro Cab, Digitrax Super Chief, ZTC Master Controller, Uhlenbrock/Fleischmann Twin Digital, These get you right away into full feature Digital Control and cost from £182.50 to £500.00.

5. CAN YOU USE DCC WITH N GAUGE.

• You can use DCC for N gauge but you have more practical problems than with HO/OO. This is because many N locos have not been made with DCC in mind and space restrictions make decoder fitting more difficult, But it has to be said that this is changing very quickly. Most new locos for the American & European modellers are coming DCC ready, some are coming Decoder Pre-fitted. 
• Graham Farish locos in particular cause problems because they have the motor built into the chassis and for the inexperienced, the necessary isolation of both motor brushes from the track can be tricky (there is a 3-wire 'fix' from ZTC & Other manufactures). However if you are one who looks on these 'problems' as an interesting challenge then by all means go ahead now, very few of the 'problems' are insuperable.

6. CAN I RUN UNMODIFIED DC LOCOS ON DIGITAL SYSTEMS/CAN I RUN DIGITAL LOCOS ON CONVENTIONAL DC.

• Amazing as it seems some DCC systems allow both these possibilities. Some systems allow one conventional loco at a time to run just as if it had a decoder fitted (Address 0). There is always a 10000 HZ hum from the loco. I would consider this feature as a temporary expedient and not something to be done on a long term basis. 
• Virtually all NMRA-compatible decoder fitted locos will run under conventional DC control, but PLEASE, NOT WITH FEEDBACK CONTROLLERS OR ON LAYOUTS FITTED WITH RELCO (OR SIMILAR) ELECTRONIC TRACK 'CLEANERS' . The decoders are not by-passed during DC control but recognize the nature of the DC power and react appropriately. If a decoder has been programmed for inertia settings for acceleration/deceleration then these are still present under DC control. The quality of running of DCC decoder fitted locos under DC is excellent and virtually indistinguishable from normal. It is possible to cancel this feature in most decoders by programming.

7. CAN I FIT LOCO DECODERS MYSELF.

• Yes. In fact we would advise anyone to do this after perhaps having the first decoder fitted by the shop if they are a bit unsure. Once the simple principle is understood it can be easy, particularly for OO modellers of the diesel/electric era. Difficulties are often nothing to do with the wiring but are practical ones of finding space and figuring out the circuits on printed circuit boards. The one piece of essential advice is 'Never apply full power, whether DCC or Conventional DC, to a loco to which you have just fitted a decoder until you have checked it out fully on the 'Programming Track'.
  More and more locos are now being made with the standard NMRA/NEM socket for 'plug-in' fitting and provision of a space for a decoder.

8. CAN YOU GET ME A DECODER WIRING DIAGRAM FOR MY particular LOCO.

• Not always. Some fitting instructions can be found on the TCS web site; http://www.tcsdcc.com/installation_pictures_and_inform_index.htm
• You should understand what you are trying to do before starting to wire up a decoder.

9. CAN I WORK POINTS AND SIGNALS USING DCC.

• Yes. Points and signals can be worked digitally. There is perhaps not the same 'quantum leap' with point and signal control as there is with loco control, but it does reduce wiring considerably. However it does come into its own when using route setting and automatic signal aspect control often with a computer. This type of operation is changing all the time with new features coming out all the time, from most of the manufacturers.

10. CAN I RUN DCC USING A COMPUTER.

• This is of course possible, often using an additional 'Computer Interface' unit. There is a degree of misunderstanding about model railway control using a computer. Modellers tend to split into two violently opposed pro and anti camps when computers are mentioned, but the truth is that a computer can save endless hours of wiring and control panel building even if you still want to drive your own trains and don't really care for computers. Just a few years ago the thought of using a £1500 computer just to drive model trains was rightly thought the province of the eccentric, however with new and powerful computers costing under £300 and second hand for half this price then it begins to make sense. Just 4 wires connected to the layout can enable you to control a quite complicated layout from an on screen track diagram even with automatic route setting if you want. Some DCC software is available over the web on shareware.

11. WILL MY NMRA COMPATIBLE DCC SYSTEM BECOME OBSOLETE AND VALUELESS LIKE THE OLD HORNBY ZERO 1.

• The answer here is an emphatic 'No' thanks to the NMRA. A standard electronic format means that even should the maker of your DCC system go out of business your trains will still run. You can replace some or all of your equipment, if necessary, with that of a different maker and it will still run your locos without changing the decoders.

12. ARE ALL NMRA COMPATIBLE SYSTEMS THE SAME.

• No. Just as all VHS video recorders and PAL TV sets are not the same. They have different features even though they share the same electronic format.

13. WHY ARE THERE SO MANY DIFFERENT TYPES OF LOCO DECODERS.

• There are different parameters for different uses. An LGB loco takes a lot more current than an N gauge loco. Physical size needs to be restricted for N gauge. You may want to work lights, a horn and even another feature on one loco. Some users want feedback decoders which can give incredible slow running characteristics. Some users want a no frills decoder at a budget price. So all these features lead to different decoders and different prices. Bear in mind that all NMRA decoders will work with different systems, just because you have a digitrax system you don't have to use only digitrax decoders.

14. WHY DO SYSTEMS HAVE 'BOOSTERS'.

• Even a relatively modest HO/OO layout can use considerable power if sound, multiple headers, steep gradients, heavy trains and lighted coaches are used. As with a real railway, the system may then need to be split up into power districts, to avoid excessive current draws. This is done with each section using a separate 'Booster' and transformer. However, control-wise the layout remains just one section. Generally, if your total power requirement does not exceed 5 amps then you will not need a 'Booster'.

15. WILL MY SYSTEM BECOME OUT OF DATE IF NEW FEATURES BECOME AVAILABLE.

• Forward and backward compatibility has been a significant feature of the Lenz and most other NMRA compatible systems. For some systems reasonably priced upgrades are available if you want to take advantage of the latest developments. For Lenz, so far, all new decoders have been operable by non-upgraded hardware.