Wiring Your Model Railroad for DCC--Problems (111)
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- เผยแพร่เมื่อ 16 มิ.ย. 2024
- DCC wiring is a lot different from good old DC and I explained the differences in video 110. In addition, because our DCC power buses are both power lines as well as data transmission lines there are other more complicated factors that come into play which can create problems unless dealt with. In this video I'll give you a heads up on these potential problems and more importantly give you some solutions that you can try IF you are experiencing some of the symptoms that I explain in the video. Please watch the video to the end since I may answer any questions you have there.
Below are some important links for more information on these issues.
Snubbers and RC Filters
ncedcc.zendesk.com/hc/en-us/a...
Inductance and Snubbers sites.google.com/site/markgur...
Speaker wire
www.parts-express.com/cat/hi-... - แนวปฏิบัติและการใช้ชีวิต
Old retired electrician here and Larry makes many good points. Information here that is very good and must be at least considered.
Larry, the last 2 videos have been great, full of a lot of information about DCC and the wiring. Learned a lot about it from your channel. Thanks for sharing and stay safe. Ken
Excellent Video Larry....Thanks for the help/info earlier.
Philip
Ordered "Wiring your model railroad" on Amazon yesterday and arrived this morning.....without a doubt so much information!!
Learned a lot, very clearly presented! Thank you!
WOW! Gary, I can't believe the continual progress you are making. Great ideas, and I can't wait to see the lower lake and source waterfall. As for the Reversing loops, I still recommend the newer solid state BXPA1 over the AR1s.
Another advantage of purpose produced speaker wire is that it is specifically designed and engineered (good speaker wire that is) to manage high frequency signals at a frequency much higher than nominal DC electrical (e.g. auto) cables and standard domestic cable (60/50 Hz). Speaker cable is much less likely to build up the kind of capacitance and inductive loads seen in classic DC wire based DCC buses.
A very informative and well explained video! Thanks! Been away from the hobby since the early 90's (HO scale) and started my collection for about a year and a half now plus gathering as much tips and tricks as possible before I commence my layout (now in N scale 😛). I also heard you don't loop your DCC bus, otherwise you end up with two DCC signals going in two directions! 😲
Another good tip is to ensure that you do not have any long runs where an AC or DC power bus run parallel to your DCC (data) bus. Always keep them a good distance apart. When you have to have the two types of buss cross each other then ensure they cross at as close to right angles as you can practically achieve. Cables running close and parallel are another form of "noise" generation. Some data communication standards actually specify minimum etc.
Really good info, and very correct...
Uh oh. I’m going to have a flashback to my Cadet Electrical Engineering class in 1979. E fields, B fields, right hand rule. Twinkle, twinkle little star, E = IR. Thus concludes my recitation of the extent of my Cadet knowledge of “juice”. I do remember having a 22 page final exam. Left the first 8 pages blank except for my name. Class average was a 42/100. Thank goodness for the curve! 😝
Thanks Larry!
Another great video Larry! I am in the middle of my wiring so am learning a bunch. I had heard to twist the wires but never heard how often. Your tip of three times per foot really helped. Thanks for putting out all of your knowledge on youtube!
Ne aware that you can purchase pre-twisted wire. I saw it on the DCC Conceots website just yesterday and there likely are other sources as well.
Thanks you may have solved my problem will let you know.
Thanks Larry very informative. I also use digitrax and began to experience problems with run always and decoders losing their addresses. I did change cv29 on the runaway train and it seemed to work but still had decoder problems. I was advised by digitrains in the UK to fit dcc concepts bus wire suppressors and touch wood since I've had no problems. However I think I'll look into using the speaker wire as a bus. Thanks again Andy
Try the bandaid first and see if that works for you.
I live in the UK too and will be using Digitrax DCC. Do you think that using Speaker Wire might make continuity an Issue, I know Speaker Wires are coded but having say one Black Wire and one Red Wire make it less likely to get the Bus/Dropper Continuity wrong?
One of the things i would recommend is a telephone cable checker
Hi Larry, very informative video and interesting. I have been using speaker cable for my power buses, so is good know I have made a good choice for my bus wire and I have just fitted the NCE snubbers to the ends of my bus wires . For information, DCC Concepts here in the UK do their own equivalent of the NCE Snubbers. 😃
I’ll have to give theirs a look. I am petty sure they are an NCE dealer so for them to have snubbers too is not at all surprising.
Gary! Hey my name is Jeff and I'm going to be using the NCE system on a N scale 3 sectional layout each board is 63 ½ × 32 ¼ and I have flex track and manual turnouts thru out. My question is with there being two wires the same color and sealed together inside speaker wire how do we set the bus up for the black and red feeder wires? Do we split them and use one side or both? Before I go out and buy.... Also is 14 gauge good for the bus and 18 for the feeders?
Larry, all of your videos are very educational and we thank you for sharing. I also use Digitrax, as do some of the commenters below, and would like to let you know that I checked into the snubbers about a year ago when this topic came up and I found that Digitrax specifically stated not to use snubbers with their system. I don’t recall if it was written in the snubber directions or in the Digitrax directions. If you can’t verify it and need it, let me know and I’ll try to find it. It’s around here somewhere. Lol.
I have never seen any specific written guidance. As I remember AJ Ireland told me he felt that he had designed enough filtering capabilities into the command stations and boosters to counter the effects of inductance. This is why I always tell folks to check with their tech support reps first as recommendations change over time. And of course with well planned power distribution it is possible to design a layout without power buses over 30’ in length which should negate most inductance effects. I believe that the more recent Digitrax recommendation on twisted bus wires is to help with electronic noise rejection. It is interesting that NCE is adamant about the effectiveness of twisted pairs and snubbers whereas Digitrax is not. Interestingly on the instruction sheet in the NCE snubber package it says that they can be used with any DCC system, a surprisingly broad statement. If you do find some written statements from Digitrax with regards to this I would like to see it.
Now a little additional perspective. I was at my friends one day testing his very large Digitrax powered layout for short detection using the old quarter test. We were popping shorts all over to see if the command station would reliably shut down. After a few minutes we got around to his yard and found the turntable pit full of locos. The shorts had resulted in runaway behavior and the locos shot out of their roundhouse stalls into the pit. Remember that runaways are one of the symptoms. I also know that Digitrax owners also experience CVs with changed values, at one time it happened to me. And I have seen loss of control. Fortunately I have never experienced a blown decoder. On the Piedmont Southern I have never experienced any of these symptoms since I installed the speaker wire and snubbers, even with 8 amp boosters. Your results my differ.
Wow, sounds funny now but I’m sure your friend didn’t think so at the time. I’m gonna have to go digging but I’ll see if I can find it for you. I was surprised myself. I had already bought the snubber and planned to install it when I found the info. While I have you on the side bar, what were your reasons to go with Digitrax and when did you get the dcs240 and how do you like it. I was considering moving up too. I chose it because I want to do signals and maybe computer control one day. Did you ever set yours up and how was it with Digitrax. Thanks.
Long story. Back in 1994 I was a contributing editor for Model Railroading magazine when Digitrax contacted us to do a product review of their first DCC system so I agreed to do it-I’ve been a Digitrax user ever since. They have continued to send me new products every time they release one (as have many other manufacturers). I reviewed the DCS210 and DCS240 when they came out and I loved it. The integrated PR4 and USB interface makes using DecoderPro so easy now. Plus the ability to upload new firmware when released means I can keep it up to date without a trip back to Panama City. I could have gone with any of the systems available but I have stuck with Digitrax because it is a complete system, with highly reliable components-I still use 20+ year old throttles on the layout.
I was working in theater when moving lights started coming out, and this created a lot of issues in DMX, the digital control system for lighting at the time. We had to put 180 Ohm resisters at the end of a run to resolve the issues. I am very curious if this is the same sort of thing happening with DCC. Do you have to be named Larry to be a DCC expert, LOL.
Was wondering if you will touch upon cab bus wiring too. I use NCE currently and on a previous layout (10 years ago) used telephone jacks that have the hook up screws behind the cover, daisy chained in series with no issues. Now I keep on geting opens and shorts using the LAN tester you recommended on a previous video and can't get my CAB04 to work at all unless it's right the factory NCE panel . I even had it sent out for repair and came back with no trouble found. I enjoy watching your videos much more than working on my own wiring lol, thanks!
I don’t recommend using DIY throttle panels for that very reason. These usually have their own circuitry associated with them which is difficult to back engineer a d get to work reliably. I only use Digitrax UP panels on my main layout and will use NCE panels on my modules.
Hi Larry, really appreciate all your excellent videos, just ordered both your books as I am building my first DCC layout. One question and a suggestion for a video, reverse loops and reverse crossovers! When the reverser does it’s job and the train leaves the loop, is the entire rest of the mainline in a reversed state?
No, the autoreverser circuit is physically and electrically connected just to the isolated rails making up the reverse loop. Therefore only the polarity of those rails are affected. You need to leave gaps in both the rails at the turnout rails on each end of the reverse loop.
So you can use speaker wire for your bus lines?
Also, thanks for answering my questions the other day, seeing your responses and watching this and a few other of your videos answers everything!
Yes, just make sure to get the correct gauge for your scale and bus length. Lowes and Home Depot only carry the small stuff as far as I know.
So another question, I have taken out the feeders, and that seems to have fixed my issue, so I did have a faulty one or two, the track now reads 14.3 when I put the micrometer to it(read 12.3 before I took the feeders out in a lot of places) I had around 30-40 feeders connected with suitcase connectors, should I re do the entire bus line from scratch? Because there is so many connections going no where? Or is it fine to leave the bus the way it is? I have the wire and it would take me very long.
The group I belong to has found that when we try to put two sets (two or three engines with stay alives ) on the layout at the same time we loose everything and have runaways . It seems the draw of all those capacitors loading up at same time draw a huge amount of current. We were able to stop that by breaking layout into 6 power zones using power breaker cards. I like to call them power distribution cards.
I made some snubbers for layout but haven't installed them yet.
I hope you're using multiple power boosters, ideally six in your case. If you have areas with lots of switches, etc. You can divide them up using short management devices and perhaps get away with three or four boosters. Sole math, add up your locomotives and lighterd cars and caboose by amperage drawn and see if your boosters have the capacity to handle the load.
Larry, Did you use solid wire for your feeders or stranded? with the stranded speaker wire...
I use solid wire for feeders. I find it easier since it doesn’t flex as I am trying to hold it in one place while soldering.
I find your wiring videos very helpful. I want to use 12 g outdoor (low voltage) copper stranded wire out to my 14 g twisted pairs sub buses in several power districts over 30 feet from the booster / circuit breakers. Is this 12 g outdoor wire equivalent to speaker wire, or might the vinyl sheathing be too thick to solve the inductance issue. Thanks Larry
I have no idea how thick the insulation is. All I can say is the damping effect of twisting is proportional to the distance between the two wires. Thicker insulation increases that distance and reduces the effectiveness. You would need an electrical engineer with a degree in electrical theory to calculate the actual loss in effectiveness due to the thickness of that insulation. Your best bet is to try different wiring patterns to reduce the length of your runs.
Hi Larry. If you use the twin speaker type wire, how do you ensure you connect your red and black droppers to the right + /- bus wire? I appreciate DCC is like AC and switches polarity but we're always advised to wireblack to one rail and red to the other consistently to avoid shorts.
The wire has a clear vinyl jacket and one side is copper in color and the other is solder coated so is silver in color. I designate the red side as red and the silver as green in my case. It also has a ridge molded into the red side so even in the dark it is possible to determine which are the red and green sides. And if you have deep pockets you can get zip cord speaker wire in a red/black vinyl coat.
I'm just starting out in DCC with MRC Prodigy Express 2 starter set, with which to experiment/learn. I noticed your 14 gauge speaker wire is Audtek. Is it the stranded 100% copper, or the way less expensive stranded CCA (copper clad aluminum)? Can you solder/splice/extend end-to-end, a bus later as the layout grows? I'm going to use either 12 or 14 to start, so it's heavy enough if I lengthen the layout later on. Lastly, you say no loops. That's just for the bus, right? Not for the actual track, as in a continuous loop of track with the train just going round and round. Thanks, and love your expertise and detailed explanations in your videos.
I use the oxygen free copper (OFC) not copper clad aluminum (CCA). yes you can extend a bus but it is best to keep total length under 30’. You can use reverse loops on the layout but bus wires should be run in a palmate or similar pattern just don’t connect the ends into a continuous loop.
@@TheDCCGuy Thank you Larry.
VERRY GOOD SUGESTION, AS AN ELE. I PUT A GFCI FOR THE MAIN CONTROLER. THAT SUBER AS U CALL IT DOSN'T HELP IN BROWN OUTS. Q-2 , U DID A SEGMENT ON PECO CODE 55 S/W'S TO MAKE THEM DCC READY. WHAT ABOUT IF IM RUNNING JUST DC, DO I HAVE TO DO ANYTHING TO THE S/W OR TURN-OUT ?
I am curious as to how all this would be dealt with for block detection. How will snubbers affect detection? How would one go about twisting wires for common rail block detection? Would you need to wires to every block so you can twist them? So many questions.
It does create issues but there are work arounds. First snubbers have to be placed before current detectors since they do use a little current. On the Piedmont Southern I use the speaker wire but drop the detection common off when I get out to the block and I only put detection on the main line and not on sidings or in yards. This keeps those runs much shorter than the speaker wire in most cases. Also none of my buses are over 30’ long so I could get away without using the speaker wire but I need to test what I recommend so in it went. I’ll eventually go back and deal with these side issues in another video when I get around to detection.
With due respect, I have worked on several large home and club DCC layouts with parallel buss/ feeder wires for 20 years, and we have never had the problems of which you speak. We keep power districts no longer than 30 feet and use multiple power boosters. We also monitor voltage closely and carefully match booster output voltage across power district boundaries.
The CV confusion issues we have had are manufacturer based (QSI) problems, not system wide. We were having runaway problems until we disabled DC mode on all locomotives. Runaway problems solved. If you are trying to skimp on buying power boosters and using power districts significantly longer than 30 feet, of course you'll have voltage and signal problems.
You have your answer in that your power buses are under 30’ long. As I said in the video inductance becomes an issue when buses exceed 30’ and at higher amperages. It sounds to me like you are already doing everything I suggested in the video.
When using 14 gauge speaker wire as the DCC bus, do you recommend copper over CCA?
Yea, avoid the less expensive CCA.
Larry! Hey my name is Jeff and I'm going to be using the NCE system on a N scale 3 sectional layout each board is 63 ½ × 32 ¼ and I have flex track and manual turnouts thru out. My question is with there being two wires the same color and sealed together inside speaker wire how do we set the bus up for the black and red feeder wires? Do we split them and use one side or both? Before I go out and buy.... Also is 14 gauge good for the bus and 18 for the feeders?
The zip cord I use actually has different colored wire that you can see through the transparent vinyl cover. One is plain copper which looks reddish orange and the other side is tinned somis silver in color. Most zip cord also has a rib molded into one side of the vinyl. Your 14 gauge will be more than adequate and you could likely get by with 16 gauge. I use 20 gauge these days for my feeders and would suggest that for N track as it will be easier to hide.
Thank you so much! I will definitely go with 16 gauge bus and 20 gauge feeders. Is the spacing every 3 ft or inches two apply two feeders? Also should I put frog juicers on every turnout?
Are these "fixes" only for issues on a DCC layout? Also, is an RC filter compatible with DCC block detection?
Yes, this is a DCC video. I don’t believe the RC filters cause detection issues, at least I have not seen any issues as they don’t become conductive unless there is a voltage spike. Twisted wires can be an issue with detection using current sensing transforms like are used o the NCE BD20 and many others. The solution there is to place the detector after the twisting. So I use untwisted wires as sub buses off the main bus for the detection sections. You can also use a special capacitor arrangement and I cover all this stuff in the book.
Hi Larry,
question about snubber placement?
I have a main bus , and a sub bus for the feeders
Should the snubber go at the end of the main bus ? or at the end of the feeder sub bus?
Thanks
I would put one at the end of each bus and sub bus but only if your runs exceed 30’. So if the main bus is 30’ or longer put one at the end. If the total length of the sub bus plus the section of the main bus it is attached to is 30’ or greater then it would need one too.
Ok so then if my bus or combination of buses,
Turns out to be less than 30 feet, Would you not recommend using the snubber?
Thing of these as a bandaid that you apply after a cut, and any short or power related problems are the cut. There are a lot of factors such as wire size, length of run, booster amperage, and wiring practices that create the problem that a snubber should solve. But if you don’t have the problems don’t apply the bandaid.
Is it the same process soldering solid to stranded in the middle of the wire?
I use suitcase connectors to connect the feeders to the main power bus.
Did you find Bus/Dropper Wire Continuity a Problem when using Speaker Wire in lieu of Coloured Wires ie Black and Red?
Not really, the speaker wires are bare copper and copper clad with a thin layer of solder, so one is red and the other silver. Also the plain copper wire casing has a couple of ridges cast into it so you can literally tell in the dark which is which. 14 gauge speaker wire sells for about $0.15 a foot whereas the red and black type is about $0.60 a foot-call me cheap!
The DCC Guy Many Thanks for your prompt Reply, I live in Southern Britain and too use Digitrax. Really great Videos.
need a show in removing chokes/filters from Bachmann DCC decoders that interfere with programming
See video #79
You ever had a turnout when thrown kills the signal to the other tracks train is dead . Till you throw it back or when you park your train at the engine facility shout down track power the engines with a older decoder address 03 takes off with no control till you put power back on or before you shout down the track power I have to make sure that the switch is thrown. So no power on that line. Before I shout down track power also analog engines just take off at full speed even through no track power. Also when you shut down track power train still have power and idle but no control is that normal. Also the command station power light flashes but the power on light on the booster flashes like a strobe light is that wright . O.k Larry thank just trying to debug my layout. Small problems. Between 2 districts.
Check your wires, you have something crossed-99% of the time that is the answer. I have known guys who worked on fixes for months only to finally find the miscreant wires.
so with dcc. i have been told the wire has to go from one end of s layout, to the other.
with dcc you cant make the wiring a loop;
true oof false ?
Hey Sparky from my understanding that is true because it will send 2 signals around the loop and may reach the locomotive at slightly different times, which may lead to problems
You can make a loop, just gap the loop. Leave a couple inches between the ends of the loop.
What they said!
Loops are not good. You cam T it or Y it or run it palmate like the fingers on your outstretched hand but don’t loop it in a continuous circle.
I can't tell you whether it's right or wrong, but i can say my first layout was a 4x8 ply board with 2 loops... i had my 5amp dcc connected directly to the track and i ran 2 trains for months with no issues.
My wiring is in. I am probably going to eventually light my structures with 12vDC, but not yet. I had Digitrax and switched to NCE. No twisted wires, and as of yet I have no issues. If I install DC for accessory lighting I will try and keep that wiring away from my Bus. So since I cannot twist the wires at this point can I cable tie them against each other and would that work?
To work effectively the wires need to be in intimate contact over their entire length. Cable ties are unlkkely to give you that continuous contact. Try the bandaid first.
The DCC Guy I have a bus split into 3 sections one Maine bus with a PSX circuit breaker and an return loop on each end with a PSX reverser
Do I need 3 bandaids for this setup ?
Are you seeing any of the 4 symptoms? If not do nothing. It sounds as though you have one main bus with power drops off it for the return loops so you likely would only need the snubber on the very far end of the main power bus.
The DCC Guy no problems yet but I do not have dc power installed yet for scenery lighting purposes and I don’t feel it is necessary to use DCC for that purpose although once I eventually get a booster I guess it wouldn’t hurt anything to go full DCC
I like to keep things simple so having a 12VDC power bus for accessories and lights does that for me.
Searching on Google for "16 AWG twisted pair cable".turned up spools in 25 ft and 50 ft. lengths for less than $30. It was more common with solid core so must look carefully.
16AWG is pretty common and may even be available at Lowes or Home Depot. The 14 and 12 AWG is a little more difficult although I see that All Electronics now carries it in addition to parts-express.com .