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Confused With DCC Bus Wires
Bruce models HO and asks readers:
“I’m building a new layout in my garage 24×20. Should I run my bus wire from point A to halfway around one direction, and the other way to half way around, but not joined together at the halfway point? Or should I just make a single loop from point A to point A. Regular street talk will be best for me so I don’t get confused by all the tech talk thanks. Thanks.”
14 Responses to Confused With DCC Bus Wires
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Bruce,
You don’t need to do a loop at all. Just run your 2 busses wherever you need power to attach your track feeders. My layout is only 26″ wide so my bus will be nearly down the middle so my track feeders can reach it from every piece of track. It will end up being connected at the power supply and ending wherever your track does. But it doesn’t have to be a circle. Hope this helps.
Hi. from what i have been told do NOT make a complete loop. my layout is 16’x40′. I have a loop run from point A to half way around both directions then i have the track double gapped as not to have a complete electrical loop like you are talking. it is working very well. hope this helps
Nice big layout ! You get the best conductivity (sorry, tech word) by having more electrical conductor going to where the power is needed. More is better, so join your bus wires all the way round, then current can flow both ways round to the loco with least resistance.
I say to all model railroaders, please do a bit of studying up on basic electricity and electronics, and you will know the answers to a lot of the questions asked on forums like this. There are many free online courses.
Bruce
Electricity works like a river, where the water will always seek the path of least resistance to its displacement.
In a lay out, it would be enough to bind two wires to a certain point of layout that electricity would be distributed to all points of the circuit that could reach by creating your own path always choosing the one that offers least resistance.
If our rails were mounted in one piece, it would be easier, but it is not and, by the way, we still have several joints that add more or less resistance to the path of electricity.
So it is usual for us to create a freer way of interruptions to aletricidade reach the appropriate points without much interference amendments.
As this wire will be responsible for loading all the power necessary for the operation of the circuit, it should normally have a higher caliber than normally used for the connection on track, but there is no need to leave and return to the same point forming a loop.
They may be various ways out of the power source, and proceeding to directions where they reach this point the shortest path possible. When further is the connection point, more direct should be such a link without ramifications to be made before it.
Select more distant areas elimentação supply to be fed individually and connect directly to a pair of wires and the end of this make the required branches to feed this area.
Even in a layout of large dimensions, it should be needed many of these feed paths.
The greatest care should be taken is to connect the right track to its corresponding wire because a small error, a single wire connected to the wrong track, put the whole system in a short circuit and is usually much more difficult to isolate the cause of the problem.
Greetings
J.Oscar from Brazil
My understanding is that the bus wires under the layout do not need to be a closed loop. In fact closing the loop might end up shorting out the layout if you muck it up.
Connecting the rails to the bus wires for each individual piece of rail is probably the most important thing. Relying on rail joiners alone, or even soldering the rails together might not, in time, prove “permanent”.
Make the bus wires as heavy a gauge as you can – bigger diameter in the bus wire equates to less resistance and better performance
A BIT OF WIRING HERESY
A bus wire is potentially a good idea BUT it is not essential on every layout.
I have about 250ft of track (Peco Code75) which includes 4 loops of about 40ft. All tracks are joined together electrically so that all tracks share the load. Because the tracks are a ‘ring-main’ I effectively have 8+ve and 8 –ve conductors (i.e. 4 in each direction). Nickel Silver tracks are not good conductors but 8 of them are probably better than a single copper bus wire.
With no load, my power supply measures 15.48v and at the most distant point it is 15.46v.
Running 6 engines at once, at realistic speeds, that drops to 15.36v and 15.33v.
3/100ths of a volt drop makes no difference.
thanks for all of the replies this is what i got from them it really doesn’t mattert much if i do a loop or a a to a but not connected as long as i put feeders all the way around the layout at every 3 foot interval is this right?
A few years ago, I went to a train show and talked to one of the operators of a rather large HO layout. He told me that they made a connection to the main bus every 2-3 feet. We did not discuss whether or not the bus went all the way around, or if they had multiple “circuits”.
Having multiple circuits would seem to be an easier way to troubleshoot any problems. Hope this helps.
Running ~500 ft of 2-rail American Flyer track. Ran two pair of 14 gauge loop busses, black for ground and red for power, with drops every 4 feet. Loops offer the path of least resistance for electricity. Just be consistent on which rail connects to which color, and isolate wye’s and loopbacks. As a rule, in the clockwise direction I put red (+) on the right-hand track. For my loopbacks, I used colored LEDs to show which section of track the loop is currently “in-sync” with, and a double-throw, double-pole (DTDP) switch to throw after the train enters the isolated section to sync it with the upcoming section. This could have been done automatically for some pretty big bucks, but I like to participate in running the trains.
Doug got it right. If you make a complete loop your DCC signal will get out of phase. If strange things start happening the track probably didn’t get double gapped. Most layouts will not see a problem because they are too small or so large that a booster is needed. So the track gets double gapped any way. Voltage Drop is not the only consideration when dealing with DCC. 14 gauge wire cures a lot of problems. Mine are 14 Buss wires and 18 gauge drops.
Hi Jim, what do you mean by “out of phase” and “double gapped” ?
Electrical signals travel along wires at the speed of light, so a signal going both ways round a (small model railway) loop will experience no significant phase change at the frequencies used by DCC.
Double gapped means that the track is joined by a plastic rail joiner on each rail. As for out of phase signals they don’t stop were they meet. They go round and round until the data is total trash. when you leave DC and get into DCC you get into electronics and super position theory and all that complicated stuff. I’ve been out or school 30 years and it was confusing then so I’m not going to try to explain it all now. As for the speed of light, well maybe if there aren’t to many propagation delays built into the wiring. Coiling up some excess wire forms an inductor. Any little thing can cause a problem. Good wiring practices can avoid mast of them.
mast of them ??? See just talking about this stuff can cause a short between the head sets.
thanks to all of the respondents to my questions you all have been a great help.. Now all i need to do is get off of my lazy @ss and get to work on the new layout. THANKS A BUNCH