My new Lenz Set 100 showed up at the door yesterday. I sat down last night and was reading through the manual for the command station. One of the things that kept catching my attention was that it said all wires (ie bus wires) needed to either be parallel or "a twisted pair". For the most part my bus wires will be running parallel, but there will be a small section for each "district" where my red wire will be routed through a toggle switch before connecting to the bus wires and the black wire will go directly to the bus for that district. I have set it up this way so I could turn parts of the layout off if need be and to help locate shorts or other problems a little more quickly. Anyway, at the locations where these wires aren't exactly "a twisted pair" or running parallel, is this going to cause a problem?? I don't think it will but I want to make sure. The manual cited something about a "resistance ratio" or something like that.
This will be fine, we have it set up this way on a 130x27 foot layout, so it won't be an issue. Twisted Pair wire is actually sold as such.
I wasn't planning on creating my own "twisted pair" wire. I was just concerned that for the 12 inches or so that the wire isn't actually parallel if that would cause a problem. I personally don't see WHY it would matter if the wires were parallel or not, but I'm not an electrical engineer.
Scary thing is, I am and I could tell you why they want it in parallel and why it doesn't really matter.
Do tell!! Ummm...in simple layman's terms of course... I'm curious.... [ 04. March 2003, 21:33: Message edited by: Hoss ]
Ha, ok. Basically it is to prevent cross-talk between different busses (twisted pair or parallel wiring will do this). However, if you are not crossing different busses, it really won't matter. And by bus I mean a bus pair. Simple solution? Keep your wiring neat.
Hmmm....that brings up a question then. I'm going to have several pairs of bus wires running in close proximity to one another (I have 3 tracks set up on 3 different pairs of bus wires). Do I need to maintain a certain amount of distance between bus pairs?? Also, there are two places where one pair of bus wires will cross over another pair of bus wires. Am I setting myself up for problems?? That's not even taking into account the feeder wires that will be dropping down (some possibly crossing over other bus pairs). [ 05. March 2003, 20:24: Message edited by: Hoss ]
In the April MR, in an article about bus wiring, they mention that DCC signals will throw out interferance to phones and such, and to prevent it to loosly twist the wires together. Just thought I'd throw that out.
Sorry if this seems a little "out of it" but I just picked up on this topic and am very curious. What is bus wiring?? Do I need it for Atlas DCC system and any more details you guys can give me would be great. My current layout is pretty messy when it comes to wiring(and everything else) but I am moving in June and will be building a much smaller layout(I know smaller but atleast I'll be able to get something done) and I want to use all these new techniques I've learned on it. Thanks Matt
Bus wires are basically a pair of heavy gauge parallel wires that run the distance of your layout...generally directly beneath you track. Feeder wires will then drop down from the rails and are normally soldered to the bus wires. It's just a good way of ensuring that you have good power all the way around...and it's HIGHLY recommended (if not absolutely necessary) for DCC. I use 12 gauge stranded wire for my bus wires and 20 gauge solid for my feeders. When I spoke of having several pairs of these, that's because I have chosen to break my layout down into "districts". I have a pair of bus wires for my #1 main, a pair for my #2 main, a pair for my branch line and a pair for my yard. Each "district" is fed by the command station through a toggle switch so I have the ability to turn off the different districts so the whole layout isn't "hot". This isn't necessary, but I wanted to do it because it could help me locate shorts or other problems better....and it would make it easier for me to install boosters later if I ever turned these "districts" into separate "power districts".
We've got ours set up as following: Power district - 1 pair of 12 gauge wire Signal block - 18 guage wires, a "sub-bus" for a stretch of line. One of the wires goes to a on/off toggle for troubleshooting purposes. Feeder - 20 (or 22) guage wire. So we run one "master bus" per power district and have smaller ones for certain segments. These "masters" cannot cross, and the sub-busses all come from the same master, so crosstalk becomes almost nil.
Yeah...that's where I've got some re-routing to figure out. I've got two spots where my bus wires cross....
I thought bus wiring in the DCC and twisted pair context referred to the wiring from the command station to remote cabs, which is a communication line. The wiring to the tracks is an interesting subject, because the rails themselves constitute a longer length of (usually ) untwisted conductors than the cable feeding them.
Ah yes, this is where it gets tricky. Thinking now, the manual is probably referring to the "control bus" not the "power bus." Confusing huh? So twisted pair wire for the "control bus" is what it is looking for. Usually 6 pin phone-style wire. Don't worry about the track power, it will be fine.
So what you're saying is that it's not a big deal if my bus wires (the powered ones to the track) cross over each other...or are close to each other? I've got as many as 4 pairs of bus wires in certain places...some of which are within a few inches of each other...and in two places they actually cross over each other.
Correct. You should see the mess under our layout. The manual is referring to the cab bus, not the power bus.
So Hoss, You used 12ga wire for the bus(es) and 20ga for the drops in HO scale or a different scale? Matt
My layout is an 8' x 17' N scale layout with 2 main lines, a branch line with a few spurs and a large yard. I use 12 gauge stranded wire for the main power bus(es) and 20 gauge solid wire for the feeders. This may be overkill for what I've got, but I'd rather be over than under.
