How many twists per foot? Yard? Do I need to put in the power bus wires? MRVP's wiring doesn't have any but others recommend twisting.
Can I connect the DCC power to the center of the power bus or does it need to be on one end?
Do I need the capacitor/resistor thing at the end of the bus wire? If I connect in the center on both endS? The bus will be 50 or 60' long
Gary
Lot of questions. Answer really depends on the system. NCE suggests twisting. Digitrax does not but it won't hurt. Bus lebgth is a factor also. longer bus lengths seem to wor better with twisting. Place the booster in the center of that 50 - 60 foot run and no twisting would be needed. At the end, twist it. Twist about 1 twist per foot if desired.
same goes for termination. NCE reccommends it, Never needed it with Digitrax. Again, it won't hurt. Add it if you have problems. Forget about it if all works OK.
Martin Myers
And where the DCC system connects to the bus does not matter but you really don;t want any distance from the system to the track to be over 50 feet, even if you use #12 wire for the bus. If you connect to the middle of a 50' bus, you then have effectively 2 bus runs each 25' long. That's much more reasonable than a 50 foot run. Also, the bus does not have to be perfectly linear. If you have something that goes around the walls and then in the middle you have a 12 foot long penninsulat, you do not need to run the bus down one side of the penninsula and back up the other, You can tap off the bus as it passes the base of the penninsula and run a line down the middle. Or even tap 2 sets off the base, one down each side. This reduces the overall circuit distance, at least from one side of the room to the other. And for one side of the penninsula.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I'm not sold on the twisting, certainly not for bus runs less than about 20-25'. Even so, the twisted bus connects directly to a non-twisted pair of nickel-silver rails that transmit precisely the same voltage (+/-) and signal that can themselves be contiguous for many tens of feet. Those rails are rather close to each other in N scale, let alone HO or larger.
As long as you are at this phase of construction, you should consider dividing your layout into power districts if it's large or complex enough. You need to do this to both the bus and the track so that sections are isolated from each other. Each section gets its own circuit breaker, which makes it much easier to troubleshoot when you get a problem.
Do not "loop" a DCC bus back on itself.
My Lenz system, as I recall, suggested putting a resistor which they provided at the far end of the bus. I did that and discovered that the system really did work better.
I do not twist my bus wires. I drilled holes through the benchwork about an inch apart and run two parallel wires through the holes, maintaining that 1-inch spacing. This makes adding feeders much easier than trying to pull apart twisted wires to strip and solder the feeders to the bus.
Color code your bus wires and feeders. Be very fussy about this.
It takes an iron man to play with a toy iron horse.
When I made this decision a couple years ago, many folks were advocating twisting, some said it was only useful on long runs, some said it was useless. NOBODY said that it would hurt anything. I decided to twist. I took 30 feet each of red and black stranded 12 ga., clamped one end to a table, stretched it across the house and put the other end in the drill. I was done in about 10 minutes.
If you do decide to twist, 1 twist per foot has been suggested as the minimum that would be useful. If you accept that that twisting has value, more twist is better than less. More twist also makes it more difficult to attach feeders so don't get carried away. If you are using suitcase connectors to tap the bus (another religious debate) you can get away with more twist than if you are soldering.
I have the right to remain silent. By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.
as other have said
electromagnetic waves induce a current in a loop of wire. Twisted cable minimize interference by minimizing the area of the loop and repeatedly flipping it over, cancelling it. While it is significant for phone and ethernet because the signal levels are small and fast, DCC operating at ~14V is less susceptable to external interference.
But it certainly won't hurt and helps organize the wires.
minimizing cable runs is also helpful. Putting the command station roughly in the middle of a 50' run will minimize any losses at the far end and help isolating problems.
DCC is sufficently low-speed (~10 kHz) that bus termination is not essential.
greg - Philadelphia & Reading / Reading
The biggest benefit from twisting the bus wires together is the reduction in inductance. I tried it with a short (~3') length of wire and the difference is very noticeable. (Test done at 10kHz). Reducing the inductance reduces the impedance, which is a good thing.
https://ncedcc.zendesk.com/hc/en-us/articles/204128735-Snubber-RC-Filter
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Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Twisted Pears are necessary in network communications, not so much on your railroad.
Cat 6 cable has more twists than cat 5 cable, and therefore can carry more and faster data.
Your railroad does not and never will carry that much data. Besited for the wists to be effective, the rails would have to be twisted too.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS