A question for our DCC experts?


goscrewyourselves

goscrewyourselves

I'm the one
This is more or less a rhetorical question ... sort of. When I first started my DCC layout I was told, read etc etc that DCC was particularly finicky when it came to the quality of the track work, poor track work equated to poor DCC performance, basically. As such, I was fairly meticulous (for me) with the way I laid the track and, subsequently, wired it for power.

So a question then ... why is it that I have about 6' or 7' of new, loose laid, floating, uneven, wobbly, unsupported in some places track that runs beautifully on DCC?

Seriously guys, this new section of track is (literally) suspended in the air for around 3 or so feet and includes 2 Wye Switches and I have not had an issue running DCC over it. None of the track has been soldered, it just sits there on existing scenery and in the air. This really does make me wonder just how good a persons track work has to be, and whether or not that track work really does equate to DCC performance.

Now, before anyone says anything - NO the track work isn't going to stay this way and it will be laid "properly" but that doesn't detract from what I am experiencing. I guess the real question then is this ... if what I have is working and working well, just how good does a persons track work need to be for DCC to perform on it?

I'm ready for the bombardment :D
 
I'm no expert at all Tony, but, LUCK??? Cleaner track ???

I have a few DCC locomotives that I run on DC and have found that they are a lot more sensitive to dirty track compared to a straight DC locomotive.

I don't spend a lot of time cleaning my track as long as my locomotives run smoothly. After running a DC locomotive around the layout, at different speeds, and the locomotive respnded extremely smoothly, I put a DCC locomotive on and it was acting up quite a lot until I went and cleaned the track. After a good track cleaning they ran very well.

I would suggest you clean the tracks well and see what happens.
 
Chet,

I know DCC needs cleaner track for better power conductivity and that DC will run pretty much on anything, within reason. It wasn't so much the cleanliness of the track but the way in which the track is just sitting there. I suppose I should have said that this loose laid, suspended track runs just as well as cleaned and operating properly laid track.
 
Clean track isn't the same thing as carefully laid track. The biggest issue with quality tracklaying might be making sure the rail joiners conduct electricity reliably. Some people put a feeder on every section of rail, which eliminates that problem. But if you have loose railjoiners, that will affect reliability, though nearly as much on DC as DCC. If you have a loose, wobbly section that's conducting reliably, either you did add feeders to it, or the rail joiners are tight, for now. That'll change.
 
In a word "connections" you have good connections therefore no voltage drops hence no DCC signal loss.
 
A lot of DCC wiring and trackwork is deliberate overkill to make sure things work right. You CAN get by with fewer wire drops and no soldering, and that brand new track will work just great. In a year or three when there's a little oxidation or a rail joiner has loosened you might find it's not quite so spiffy. You might also get lucky and everything will continue to work great. It's just a lot easier to make sure to begin with than to come back and solder the track later or add extra wire drops to installed track.
 
wombat457 said:
This is more or less a rhetorical question ... sort of. When I first started my DCC layout I was told, read etc etc that DCC was particularly finicky when it came to the quality of the track work, poor track work equated to poor DCC performance, basically. As such, I was fairly meticulous (for me) with the way I laid the track and, subsequently, wired it for power.

So a question then ... why is it that I have about 6' or 7' of new, loose laid, floating, uneven, wobbly, unsupported in some places track that runs beautifully on DCC?..
Click to expand...

Because the idea that DCC is particularly finicky is a myth!
 
I have to say that I am enjoying reading the replies. What I am getting from the replies, so far, is that how you "physically lay your track" doesn't matter because that "one thing" has no effect on whether DCC will perform or it wont.

I think Mike hit the nail on the head though when he said:

"...A lot of DCC wiring and track work is deliberate overkill..."
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I am inclined to think he is 100% right. I also think that prevention is better than dealing with potential problems in the future, which is why I do lay my track as perfectly as I possibly can. I just wonder how many people get put off or panicky (as I did when I started with DCC) because of this "deliberate overkill" philosophy.

All that matters, when all's said and done, is that the joins are solid, there are sufficient feeders and the track is clean. If you have that - it all should work properly. Essentially, you could suspend your track work 3' off of the ground with string and so long as those 3 things mentioned above are in place - it all should work, if it were at all possible that is :)

The whole point of this post though was the "how important the physical laying of the track was for DCC", and that (in itself) is little more than a myth when it comes to DCC performance. How you lay the track, that is place it on the layout and what you use beneath it and how well it is fixed to the bench work, how level it is etc etc is all (virtually) irrelevant when it comes to whether or not DCC will perform or not. That is my point here, and it was those sorts of things that were included in the "this is what you need to do when building a DCC layout" in terms of track work and DCC performance.

No one, in their right mind at least, would leave their track as my new section currently is - but I think this highlights just how "unimportant" the physical laying of the track is when it comes to DCC.

By the way, I do know all of what has been said, clean track, solid connections and sufficient feeders for power are imperative for performance :)
 
I wouldn't say that. I ran some test track, held together with just tight track joiners. The loco ran out of juice about 7 or 8 feet from the leads. New track. New loco.
 
I'll add that probably multiple things that have already been mentioned at work in your favour for the moment Tony but that can change fairly quickly...btw I find that DCC locos can run very well on a piece of track, but put a sound-equipped loco on the same piece of track and things can change instantly.
 
To expand on my previous reply, DCC does tend to be slightly more picky than DC (but not as much as many people seem to think), and here's why: A DCC locomotive will tend to stop much quicker than a DC one What this means is a DC locomotive is more likely to coast over dead spots or quick shorts. If you have momentum set in your locos, then it becomes even more apparent because the loco may still coast over the dead spot but if the decoder resets then the loco will start accelerating from 0 instead of resuming at it's previous speed.

One of the reasons for the recommendation of better wiring with DCC has nothing to do maintaining the DCC signal (because of the design of DCC, if you have power, then you have the signal) or with DCC needing more power, it has to do with the fact that DCC can use more power. There are two issues with this, the first one being voltage drop. With DC, it's generally one train per power supply. With DCC, you can run several trains with the same power supply. Since voltage drop is a product of resistance and current, the more trains you run the more voltage drop you will get. If you have a DC setup and you have an acceptable voltage drop throughout the layout, if you were to switch to DCC, but only ever run one train at a time, then the voltage drop would be roughly the same with the same wiring, but if you start running multiple trains at the same time the voltage drop may become to much. The other issue is the circuit breaker. Most DC power supply circuit breakers will trip at a much less current than most DCC ones. For example, if you have a DC power supply that trips at 1 amp, and any short on your layout draws at least 1.5 amps then it will trip your DC power supply. With the same wiring, that same short would not trip the circuit breaker in a 5 amp DCC system.
 
CSX Robert said:
To expand on my previous reply, DCC does tend to be slightly more picky than DC (but not as much as many people seem to think), and here's why: A DCC locomotive will tend to stop much quicker than a DC one What this means is a DC locomotive is more likely to coast over dead spots or quick shorts. If you have momentum set in your locos, then it becomes even more apparent because the loco may still coast over the dead spot but if the decoder resets then the loco will start accelerating from 0 instead of resuming at it's previous speed.

One of the reasons for the recommendation of better wiring with DCC has nothing to do maintaining the DCC signal (because of the design of DCC, if you have power, then you have the signal) or with DCC needing more power, it has to do with the fact that DCC can use more power. There are two issues with this, the first one being voltage drop. With DC, it's generally one train per power supply. With DCC, you can run several trains with the same power supply. Since voltage drop is a product of resistance and current, the more trains you run the more voltage drop you will get. If you have a DC setup and you have an acceptable voltage drop throughout the layout, if you were to switch to DCC, but only ever run one train at a time, then the voltage drop would be roughly the same with the same wiring, but if you start running multiple trains at the same time the voltage drop may become to much. The other issue is the circuit breaker. Most DC power supply circuit breakers will trip at a much less current than most DCC ones. For example, if you have a DC power supply that trips at 1 amp, and any short on your layout draws at least 1.5 amps then it will trip your DC power supply. With the same wiring, that same short would not trip the circuit breaker in a 5 amp DCC system.
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So I am correct in insisting on a dedicated circuit for the track power only? I am going to be laying 30+++ feet of track DCC only. Plan on many Locos at once going.
 
All good points, but everyone is still focusing on wiring and joins etc ... all of which is true. My point was, and still is, how the track is on the bench work not how it is wired, cleaned etc. As I said, when I first got into the DCC thing, people told me about power, clean track and joins and so forth BUT also stated that the way the track was laid on the bench work was also a factor, one that was just as important as those other critical points.

new guy,

Regardless of whether I am running DC or DCC I always have dedicated power for the track ONLY. Everything else is run of a separate power supply with it's own wiring. So, what you are thinking is correct, so far as I am concerned anyway, have a dedicated circuit for your track and leave it specifically for your track. Amongst other things, having that dedicated circuit will help with any trouble shooting you may need to do.

I have something like 100 + feet (now) of track work. The general rule of thumb for power for a layout (DCC at least) is to run a "Main Power Bus" from your power supply around the layout, following the track plan, with the end of that main power bus connected to "last feeder" on the layout. I use flex track (3' long sections) and have one feeder wire connected to each of those sections of track. In simple and clearer terms, one feeder from the track to the main power bus every 3' give or take. That is using a 5 amp power supply though.

If you are going to have 30' (or more) then I think I would be working on that "general rule of thumb" principle, needed or not especially if you are going to be running multiple trains at the same time. Something like this:

wiring2_zps2csmefwt.jpg


Black being the track, red being the power. Another wire for the negative or ground following the power wire is needed too obviously.

As mentioned, drop a feeder from the track to the main bus every 3' or so. If you REALLY want to alleviate any possible power problems, drop a feeder for each and every section of track you put in, regardless of its length. That way, every section will (essentially) have it's own source of power and that will reduce the problem with "possible" faulty joins between sections, although not entirely.

A suggestion, and only a suggestion - once you have your track in place and ready to wire it, connect the power from the power supply to the track at the closest point to the power supply then run a train and see how far it gets before it stops or starts hesitating and so forth. Mark that spot in some way. Next, run the Power Bus all the way around your track plan, leaving it "DISCONNECTED" from the track at its end. Obviously, you will disconnect the power from the track that I first mentioned.

Once you have the main bus in place put in the first feeder (starting from the power supply working out or around) then run a train. for as far as it will run and mark where it stops, hesitates etc. Measure out about 3' from your first Feeder and put in another. Run train, mark where it stops and so on and so forth until you get to the end. The very last Feeder to the track should be connected to the end of the Main Bus.

Hope this makes sense. While it seems a lot of work, it will save you many problems or possible problems and I can tell you THAT from personal experience :)
 
One point of clarification to the above ... connect your feeder wires to the track before you lay the track THEN connect them one at a time starting from the power source. Sorry if I have confused you here.
 
Tony how you mount/lay the track to the bench work will become important as time goes by, It will make a difference to the conductivity of the rails as things begin to expand and or shrink, even warp with temperature and humidity changes. When you first lay the track those factors don't come into play, but over time they will. Those factors are important to DCC or DC track power.

All you are trying to do is to create a good electrical circuit that is reliable over a long period of time, with proper maintenance of course. In DCC the circuit is even more critical because you not only providing your locomotive with power, you need to provide the DCC signal. The signal is modulated through long and short pulses. Even very brief interruptions can interfere with the signal and confuse the decoder. These very brief interruptions may not even be noticed if you are running a DC system.

Another point; Overkill is relative to long term reliability. In Industrial mechanical systems it's called redundancy, if one fails another is there to take up the slack adding to overall reliability. The things to consider with additional feeders;
Do you need them? Maybe,
Will to many hurt? No.
How many is too many? Hard to say, there are many factors.

What I do is I add additional feeders when I see a need for them. There is another reason I love my sectional track with road bed. :)
 
wombat457 said:
None of the track has been soldered
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Yeah! I solder very few joints. I think it is a highly over rated thing to do.

I guess the real question then is this ... if what I have is working and working well, just how good does a persons track work need to be for DCC to perform on it?
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I cannot answer the question nor even really participate in the discussion in a non-theoretical sense because I don't seem to have the issues that other people have with DCC. Whether it is a modular unit, a layout with permanent track, or a loop thrown out on the floor my units seem to run just fine. Of course I live in a semi-arid region so maybe everything is due to the humidity others have? hahahaha....
 
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I don't have any issues with DCC or Legacy Command Controls, but I don't have a permanent layout. My largest loop is 36', has only 2 feeders, is not attached to the bench work and nothing is soldered. It runs great and all I have to do is keep it clean. We don't need to have experienced the problems to participate in a theoretical discussion.

I fail to see what is funny about the long term effects of humidity. Have you never seen what it can do to a sheet of plywood? What do you think will happen to the track work mounted on a warped sheet of plywood? I suspect you will have DCC issues as well as other problems. Maybe I am misunderstanding what exactly you find funny.

Only having temporary layouts in controlled environments I don't have firsthand experience with the effects of high heat and humidity on my layouts

As an industrial mechanic in the Mid-Atlantic region for over 30 years I do have hands on experience with the effects of high heat humidity.

Printed circuit boards in industrial equipment are most at risk to exposure to high heat and humidity. They often will warp causing cracks in the circuitry. I have worked on some with more then a dozen jumper wires. Replacing the boards would be easier, faster and cheaper for the customer, but they were frequently unavailable because some highly educated engineer who never left the air-conditioned office felt replacement boards would not be needed.

Takata failed to account for high heat and humidity when they designed their air bags. That has become a deadly disaster. This is an extreme example, your model railroad will not explode sending shrapnel into your face.

Lionel warns customers not to operate or store their locomotives in high humidity, it can have adverse effects.

As I said in my first post to this thread the problem is poor connections, plain and simple. DCC is not rocket science, a good conductive circuit is all you need. What it takes to keep that circuit in good working order over a long period of time depends on several factors. If you layout is exposed to high heat and humidity, don't ignore it.
 
tootnkumin said:
So it's essential to keep your wit dry.
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The layout I 'envision' is almost exactly the configuration 'Wombat' detailed. I got nervous when doing my limited research and got a TON of wired feeders! Had an hour long 'argument' with my carpenter trying to explain why a power bus was needed! He was convinced that I could run 300 feet of track with 1 power connection! And he actually DOES know a little more than I do about electricity! But not DCC! I tried to tell him "this is what they do and this how they do it"! I can only go by what I've seen that works! YOU guys are running trains, I'm not!(yet!) Neither is HE! YOU know what works and why. WE don't! LOL! IT'S NOT ROCKET SURGERY! But the unique nature of each layout requires a slightly different set up of similar components. The process of finding how far you can go before more power is needed, you described much better than I did when trying to explain to Rob that I was NOT going to 'throw down' on the whole 90 feet of table ALL at once! A small 'yard' and about 20-30 feet of loop was all I was going to put down till I figure this out a little more, THEN slowly fill the remaining area.
 
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