A Guide TO Dcc Page 10 A Guide to DCC

10 yourself low on gas when needing to be somewhere soon. So it makes sense to avoid creating situations where we know we will get in trouble later. What does this have to do with model trains? As it turns out, a lot! When setting up a layout, most hobbyists are quite anxious to fet trains rolling as quickly as possible. Sure, bench work is generally important enough to take some time to do right, and perhaps the track work. But as soon as a foot or two of rail is laid, most of us take some alligator clips to our power supply and see how it runs. This is OK to test, but all too often these temporary arrangements are hastily soldered to some track and it becomes a more or less permanent installation. When setting up a DC layout, there is not as much of a need for each piece of track to be able to handle a lot of power. The nature of DC block systems is such that each block will only power one train at a time. So typically the power required may be on the order of 2-3 amps at most, usually less. Something even a #22 wire can reasonably handle. So whats the problem? Well, DCC is a different animal. With DCC and 3-4 trains on a block (like in a yard), it is possible to see 3-5 amps pulled on a section of track, especially with sound. Thats a lot of juice. Just a few issues with using small power wiring on a DCC layout are: excessive voltage drop between the booster and the locomotive causing poor reliability of the DCC signal, additional heat within the loco and more susceptibility to dust and dirt on the track. Whats the solution? Heavy feeders! Provide a power bus throughout the layout where power can be conveyed to the track near the same voltage as what is provided at the booster. Most model railroad design guides recommend #12 AWG wire, however #14 will work just fine and even #16 works well for all but the largest layouts. From these busses, provide smaller feeders to the tracks, #18-#22 feeders every 6-8 feet, and on either side of switches. You can even use #24 as long as you have several drops onto the track, say one every 3-6'. Keep in mind most rail is nickel-silver. Nickel silver is resistant to corrosion, but it is at the expense of increased resistance in the material. Just because its Code 100 rail, it does not qualify as a power bus. Providing a bus under the layout with frequent feeders, you are providing a solid conduit of power from the booster to the locomotives. The result is you will have a fewer problems and a much more reliable system. On an aside, in general using old DC wiring for DCC is a mistake. Sure, when converting a DC layout to DCC, its fast, and conceptually easy. But recall the benefit of DCC is multiple trains on the same block of track. In DC, one train may pull an amp or two. So even a well thought out and wired DC system will likely be inadequate for all but the most basic DCC powered layout. That little ol #22 wire that fed from the toggle switch to that block worked OK for DC, now its like jogging while breathing through a straw! So when upgrading to DCC, be sure to take the time and install or replace the feeders (as well as the busses) with heavier conductors. The added cost and time to install a proper power distribution system is well worth the reduced frustration and more reliable operations later on. Programming Track Decoders will need to be programmed in some way. Most decoders offered today allow Programming on the Main (POM), and users will rarely need a separate programming track. However in some cases, a decoder will fet incorrectly programmed or will need to have some critical CVs reset that you dont want to risk ending up going to some other (or all other) decoders on the layout. This is where the programming track comes in. A programming track is simply a separate extension of the DCC track bus, however it is without the power booster and without a connection to the main track. A programming track will allow you to specifically and uniquely program a specific decoder on an isolated system. This is very helpful for doing decoder resets or testing a decoder before placing it on a powered track. Most DCC systems also allow you to read the CV values in the decoder back to the handheld controllers, allowing you to verify the configuration of a decoder. Generally, a programming track is fed directly from an output off the command station. The track does not need to be long, but should be long enough to hold your longest locomotive. A spare length of track on an unused part of the layout or even a separate shelf is most common. It is recommend NOT to combine the programming track with a segment of layout track, say via a double-pole, double-throw switch. Should a loco accidentally cross over the fap while the switch is in the programming track position, the power of the DCC power track could backfeed into the programming outputs. This could be damaging on some DCC systems. Some sound decoders take significantly more power to energize than what a typical programming track can supply. In these cases it is common to purchase a programming track booster. The programming track booster does provide additional power to energize these decoders, but not enough to cause damage. Keep in mind not all sound decoders Unlike with DC systems, all of these trains are on a single power block. DCC helps eliminate tedious block wiring

Previous Page
Next Page