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Using DCC outdoors versus indoors is almost the same. The only exceptions are for larger boosters and larger power supplies due to the larger nature of the scale. Also, you'll need to protect your electronics from the outside elements.

[edit] Advantage of DCC in the garden

Putting DCC in the garden does make things easier. For instance, no more digging up your masterpiece to run a new wire for a block, rail turnout, or even building lighting. You can have signaling without an unsightly amount of wire. And let us not forget about the world of sounds that only DCC can control. In its simplest form you need only run the track bus and feeders - this is no more complicated than a simple traditional setup, yet sound and complex locomotive lighting can be controlled.

[edit] Boosters and power supplies

The biggest difference in Large Scale, garden railroads is that the engines require more power. For this, you'll need higher current motor decoders because the engines and trains are just plain larger than HO or other smaller scales.

Along the same lines, sound decoders will need slightly more power to push larger speakers so they can be heard outside.

In order to support these higher current decoders, the boosters and power supplies will need to be more powerfull and need to be shielded from the outside elements that could cause damage to them.

Be sure to check out the track wiring page for details on wire types, guages, feeder lines, etc.

[edit] Distance between feeders

Here are some recommended quidelines for track feeders in the garden:

• 12' (4m) (or less) is a good rule. 14AWG feeders with railclaims for optimal performance. This helps with ensuring your trains don't slow down between feeders and helps ensure your DCC short circuit protection works incase of a short by not letting the magic smoke out. You do want this to be a trouble-free railroad, right?
• 18' (6m) should be your limit. At 18' (6m) distances, you will want to use at least 14 AWG feeders and stainless steel clamps. At the longer distance, the voltage drop across the rail might be noticeable to some. Also, the short circuit protections of your booster may fail.
• At longer distances you have to worry about the voltage drop, short circuit protection, and the quality of the joints. With a garden railroad, who wants to be digging up feeder buses to add more feeders? Or fix joints that have broken or corroded?

[edit] Remember to twist

Outdoor railways typically require long runs of the bus wire. Remember to twist the bus wires, and if possible, terminate the bus ends. See the track wiring page on details.

[edit] Transponding VS Detection blocks (Digitrax only)

For many people, detection blocks are unreliable. However, for automated control the compu 2000 ter needs to know where your trains are. For most, it has to do with the rain causing a small amount of electricity to be conducted between the rails which defeats current sensing detectors.

Fortunately not all is lost. It just so happens that Transponding and block detection are two completely different technologies that share the same board. You can use a Digitrax BDL168 to do detection, or transponding or both.

Thankfully, you do not need to hook up detection to get transponding. Detection tells you there is something on a section of track (detection block). Transponding tells you what is on a section of track (transponding zone).

When a train enters a Transponding zone, a PC can identify the loco, check and constantly monitor it's speed and location on the track anywhere within the zone.

Reliability: Transponding does not rely on an analog resistance, which can vary greatly outdoors with humidity and track condition. If the train can receive power, the transponding detector (RX4) can measure the current. There have been very few problems with reporting the position of trains using transponding. It should be noted that any bi-directional system using the track can be interfered with. Systems that generate a current or voltage inside the loco might have the signal degraded if there are too many devices on the tracks that consume power. The Transponding system does not generate a voltage inside the loco. It switches on and off a small load to form binary data that is detected by measuring the current being drawn by the decoder. Regardless of how much current is drawn by other devices, the small changes can be detected by the RX. This is what makes Transponding so suitable for outdoors. It is simply not affected by the changing resistance of the rails.

Let's break this down a little bit.

A BDL268 supports 8 Transponding Zones or 16 block detection sections. When detection is used with transponding you often split a Transponding Zone into several detection sections, simply because you need a lot more detection sections than Transponding zones. Because, in the smaller scales, a particular spot on the track may have both a Transponding receiver and a block detector, you will see the terms sometimes mixed together. Keep in mind that these two different technologies are both implemented on one board.

Well, keep in mind that transponding is a feedback technology. Automation can be done with Transponding, but that is not its only use. If you enable transponding right now, all of the "software" is embedded into the Digitrax Throttles and command stations. Currently, it provides:

1. FIND - this will display the zone number that the currently selected mobile address is in. Not real helpful in "G" outdoors where you can see all the locos.
2. OPS Mode reading of CVs. - This is a very useful feature for us in large scale. Much more so then the small scales. We tend to be more careful about matching speeds due to the powerful motors and forces involved. Being able to read, for example, the acceleration rate of a loco without having to take it to a program track is real handy as is a lot harder to move a large scale loco to a programming track than a little HO or N scale loco. So, the ability to program on the main while other locos are running is a real plus.

[edit] See also

• Garden railroads - Garden railroading