When I start to wire my DCC, I know to run the bus wires underneath the roadbeds below the track, and to keep the two wires about track width apart to reduce frequency interference. However, how do you guys handle the bus wires when coming to the turnouts? Do you split at that point and have two bus wires going each way? Or do you keep one continuous bus and later on wind around back through under all the branch turnout tracks with the original bus? Hal
You’re making it harder than it really should be. Take a look at this pic underneath my layout…
Just run the bus wires center line of most of the turnouts if travelling through a yard and then run feeders from there.
I also add terminal strips as shown here so that I can easily locate a bad wire. I’ve got one terminal strip for each bus only when there are large amounts of turnouts. The rest of the layout I just solder directly to the bus wires. I haven’t experienced any problems yet.
Hmmm maybe I misunderstood your post with my earlier thread. The bus does not have to connect to itself at either end like a circle. I would just solder or crimp another set of large bus wires and travel it to your other location on the layout. At the end just add some wire nuts to the bus wire to keep it from shorting out.
Huh? I twist bus wires so that any emmisions they are producing cancel each other out (standard digital signal practice). Two separated wires are like two big antennas. I think the concept of a split bus is for preventing shorts in situations like a large yard when there are so many feeders it is advantageous to use bare wire for one or both of the bus wires. I nor my club, nor any of the layouts in my operating group do this. For the club it was talked about, but rejected for various reasons.
I think the answer short answer is yes, sort of. But it depends totally on the track design. On our club layout the one true branch has its own power district. So we don’t really have a branch in the bus, a new one takes over.
Given the choice, I think twisting would be “more correct”, but with the signal level we are talking about, it makes no difference. The rails are carrying signal, too, and they run parallel. Also, given the choice, I would not make a loop, I’d have the runs in opposite directions disconnected where they meet. But again, at the levels and frequencies we are talking about, makes no practical difference. The rails are connected, after all.
I think we tend to overthink this. And we probably overbuild it. But I think excess feeders are a good idea since they help to reduce the impact of the things that we know happen over time, a broken wire here or there, a loose rail joiner, a cold solder joint, etc.
As for the DCC buss (and any wiring for that matter), keep it simple.
My buss is a #12 stranded copper that runs the length of the pike with feeder wires (#18 and even a few #20’s) connecting at least every other section of flextrack and all three sides of every turnout. This too, may be “over built”, but it is reliable.
The buss can be connected “back to it self” making for a loop, which would help with any voltage drops in a long run, but Ithink for that to really have any effect, the run really would have to be pretty long. Mine are about 50’, do not “loop back” and I have not experienced any problems with low voltage or reading packets of information.
Check out the following.
General Considerations for Running Buses Under Your Layout by Allan Gartner
http://www.wiringfordcc.com/track_2.htm#a8
Allan has a lot of information on almost any topic and his website makes for an excellent reference.
Good luck.
Sorry for confusing my post, I know not to loop the whole bus… but questioning how to cover yards and sidings with one bus, or splits in the bus. DRILINE: Your picture (thanks for taking time to send) seems to show a single bus, but the sidings and yards covered with feeders running off the terminal posts. Does this conflict with Tom Bryant’s later reference to Alan Gartners site which wants to keep feeders under 6"? If so, maybe it doesn’t make any difference. Thanks everyone for responding and solving my problem. Seems a single bus or a split bus will work, based on individual choice of max length of a feeder. Hal
There’s absolutely no logical reason to keep the bus wires apart – in fact, I used speaker wire for the bus wiring on a 20x40 foot HO-scale club layout and my home layout, and have had no crosstalk or interference problems with any of it, even when it runs bundled to the other wiring.
One logical reason to seperate the bus wires is ease of connecting and soldiering the feed wires without the risk of a short circuit between the bus wires.
For DCC, the Buss wires should be twisted to eliminate any possibility of inductive pickup. By twisting the wires you cancel any pick-up. I will give you an example on a much larger scale: I have a High Tension power line about 300 feet behind my house. There are 6 lines, each carries 115,000 volts, carrying power all the way from Niagara Falls. Back in 1968 when we first moved into our new home, on foggy, damp nights, you could see a glow around the wires, and if you actually held a long florescent bulb in the air under the wires, it would light up to a faint glow!! Some time period later, the Power Comapny began Phasing the lines ( crossing them over each other in pairs ) every two miles I believe. No more glow on the lines, no more pick up. Twist the Bus lines!!!
Although twisting cable is pereferable in the digital realm, I don’t necessarily think its required for DCC train layouts. My bus wire is comprised of two separate 12 guage wires that although run close to eachother are not twisted. Most DCC manuals recommend large diameter wire like the 12 guage. You don’t buy this stuff twisted and besides its not properly shielded. Our club layout doesn’t twist their wire either and we have not experienced problems, nor have I ever heard of users of DCC “fixing” layouts becuase their bus wires weren’t twisted.
That’s an old wive’s (MRR’s?) tale that you can also throw out. There is absolutely no reason why your bus can’t be a loop. Think of all the simple loop-type layouts that use DCC. Even if the buss itself isn’t physically looped, the tracks form an electrical loop and they all still work just fine.
OTOH, you should never loop your throttle/command bus.
Steve
Okay let me get this straight…twist the insulated buss wires to stop niose from being created but leave the BARE track untwisted. The track will pickup or create noise weather your buss lines are twisted or not. Noise will be the least of your problems if you get a short in a twisted pair of wires. Your track is not twisted no need for the wire to be twisted. remember the old saying. Keep it simple and it is easier to fix later.