From what I understand, to run DCC I would have to run a bus wire with feeders to every piece of track. What is the purpose of feeding each piece of track? Can’t the rails carry enough current to run a loco with DCC? I’m not planning on using DCC on my next layout as it is going to be fairly simple but I do want to make sure it’s a fairly easy changeover in case I change my mind.
I was away from modeling for quite some time and found alot of things have changed in that time. Most noteably DCC and quite frankly, it frightens the begeesus out of me.
The power distribution requirements with DCC are a bit fussier than DC, but no, you don’t need a feeder to every section of track. But, just like DC, relying on just the track, and particularly the rail joiners, to carry all your electrical load is asking for trouble. The issue isn’t the capacity, it’s the reliability of the connections. Soldered rail joiners help a lot, but using a heavy bus wire with occasional feeders is simply a way of providing highly-reliable power.
The “Gospel” says to use 14-gauge or 12-gauge for your under-layout bus wires. I have a modest room-sized HO layout, and I use 18-gauge wire, which is a lot thinner. I have no problems. I run feeders every 6 feet or so, with more where I have a lot of turnouts where electrical connectivity isn’t as reliable, and track sections are shorter. (Mostly, I use 3-foot sections of flex track.)
When you look at wiring a DC layout, complete with blocks so that you can run multiple trains at different speeds or in different directions, you will find that it’s a lot more complicated than doing the same thing in DCC.
No such thing as a dumb question. You CAN operate a small DCC layout with just 2 wires hooked to the track, however, DCC is fussy about power and you will have a much smoother operation with lots of feeders. I follow advice once heard; I solder every piece of track to something, either another piece of track or feeders to the bus. And because there is some resistance in the nickle/silver rails I use feeders about every 3 feet. Doing the same thing for DC will ensure adequate power to those locos.
The more feeders you use the less problems you have over time. You can get away with one pair going to the track, and it will work fine for awhile. But over time you will start having issues as the rail joiners begin to break down and corrode/get dirty. feeders at every section of track will ensure you’ll rarely have problems if the track is clean. Less can definitely be used though.
From what I’ve read, it’s not just the current that’s the problem, it’s the commands. Apparently voltage drop degrades the commands to the decoder in the locomotive and can cause unresponsive behavior. What happens is that, in each unsoldered rail joint , over time the electrical connection degrades and increases resistance which leads to more voltage drop. At some point the there’s enough to have an effect on the commands. There is also more voltage drop in using rail or small wires. So the recommended wiring is a pair of large wires as the power bus with smaller feeders to the rails - to each piece of rail (soldered together rail counts as one piece) at least every 6 feet.
In the short run you can get by with less. I had a 4’x7’ oval of sectional track (no soldered connections) with just 2 wires for a year without problem.
Ok, that makes more sense. I do plan to solder some of the rail joints, but if I remember correctly they shouldn’t all be soldered. Some silly thing about expansion/contraction.
The layout I’m going to be building would be a maximum of 4 blocks the “old” way with a capacity to run 2 trains & possibly a switcher. I’m probably going to start out with an cab control since on a layout like this it would be simple & I wouldn’t have to invest in the DCC system right away. Besides, I have the power packs & everything to get it up & running already in my shop.
On a side note, I was looking at MRC Tech II dual power packs on E-Bay the other day & the one I was watching went for $227.00. Were these things gold plated or did some people just get carried away?
Paul is correct. The DC motor in every DCC locomotive will take very low voltages as anyone using a DC locomotive knows. The decoders are, however, somewhat sensitive to voltage drops because as the voltage drops the signal gets lost in more noise, so to speak. The decoders want a clear signal.
But, there is more. The command center’s short detection circuitry also wants a topped-up voltage so that it can tell when a short takes place and trip its circuit breaker. If the voltage suffers too much from poor transmission and contact, the command station just won’t detect the short . Heat-generating amperage will continue to course through the area of the short, and that means through the decoder as well. They don’t like high amperages one little bit.
I ran a 4 x 10 layout for more than a year with nothing more than the two wires that had formerly been connected to my DC power pack. When I expanded the layout, I added a bus and feeders, but it’s absolutely not necessary.
That’s what I thought also…I thought it was going too high when it hit $40.00 and it just kept climbing from there…if I wanted one that badly I would’ve just purchased a new one & not shell out over $200.00 for a used one.
It is so much easier in almost every way. Take out the DC pack, put the two wires on to the DCC, dial up channel #3 and run. What is there to be scared of? A layout that can burn down and still have the DCC wiring in place is overkill.
The first “scary” thing is changing the 2nd locomotive off of channel #3 to something more useful.
I had good luck running leads to every third piece of flex track. That way, every piece of flex was at least adjacent to a piece that had a lead running to it. The sections weren’t soldered.
I guess for me it’s just “fear of the unknown”. I’ve never run a layout with DCC, or even seen one in person for that matter. I remember 15 years ago they installed a new CNC router for me to run at work & I was apprehensive about running it at first, but now I can do it in my sleep. So I’m sure that once I get my fingers on one I’ll feel silly for not doing it sooner but I guess I just have to get over the intimidation factor of something new.
I am new to DCC also, after too many years away from model railroading. I plan on starting my benchwork next weekend. As a new user of DCC at the local train club I can say DCC is far superior to operating on DC. I have very little expierence with electricity so I have been doing a lot of reading to get a handle on wiring DCC. I’m nervous about it, but also excited–does that make sense?
DCC can be far simpler than DC. The only thing intimidating about DCC in my opinion, for someone new to DCC, is the installation of decoders in locomotives. Overall, operating in DCC is fairly simple and highly enjoyable.
As far as that MRC Tech II 2800 transformer selling for $227 on eBay, I hope that the seller offered free shipping. A price that high makes no sense at all.
I guess I should’ve been a little more specific as to what is intimidating for me. The wiring isn’t really the issue, I was just wondering about the “why” for the bus wire & that’s been explained pretty well. Rich hit the nail on the head with installing decoders in locos. Especially in N-Scale. Fortunately for me, the only running locomotive I own right now is a cheap Bachmann train set 060 made in the early 90’s that when/if I go to DCC will probably never see service again. At that point, I would buy locomotives that are DCC ready & not frustrate myself too much. The other thing that is intimidating is initial set up of the system. There has to be more to it than plug it in & go but I’ll worry about that when the time comes. Right now, when I finally get to start laying track, I at least want to have all the feeders in place so the changeover will be as painless as possible when the time does come. I have alot to learn, not just about setting it up & running it, but also what good systems are & getting the best bang for my dollar.
The bus wires are recommended to handle voltage drop but in the short wire runs on layout voltage drop is just not big a problem. the problem is with signal loss over a given distance of track. the bus merely carries an uncorrupted signal under the layout and only sends a “fresh” supply up through the track feeders. if your soldering rail joints i would think a feeder every 6 or 8 feet would be enough. just be sure to add feeders after the turnouts because dcc is more finicky around turnouts and making sure you have a good signal and power feed at theses locations is essential.
“Never attempt anything you don’t want to explain to the EMT”…totally off topic here but that is one of the greatest lines I have every seen…and also so true…don’t ask me how I know that.
