FORUM CLINIC: 12 years using DCC - SIGNIFICANT NEW INFO!

[chateauricher]

bump

[jfugate]

I tend to use DecoderPro and speed tables a lot, since it's very easy to speed match locos for lashups that way ... hmmm seems I owe this forum another official post on that very topic.

I've got the first op session of the season (we always break for summer) coming up this Saturday, but after that I need to get back on the wagon and start posting to this here forum clinic again.

But I must admit, it's been pretty fun working on the layout as first priority for a while (instead of posting to the forum clinic)! [swg]

[Anonymous]

You can also put a value less that what you put in CV05 into CV06, which represents the "mid-point" voltage. That way you can fine tune how your engine runs so that it builds up speed slowly (CV6 < 1/2CV5), or builds up speed fast and then 'levels off' (CV6 > 1/2CV5).

Of course, to really fine-tune it you can use the full speed table, but I don't recommend doing that by hand -- DecoderPro makes it very easy, and is worth it for that alone.

[rrinker]

Since every loco is a bit different, it's as much an 'experiment' thing as anything. The primary CV you want for this is CV05, which is the 'top' voltage. The default value is 0, which means "full track power". Try settign this to 120 or so, if it' sstill too fast, drop it even more. This one change was all I needed to make a Proto2000 SD45 run better - out of the box it did somewhere around 200MPH.
In theory this will reduce pulling power - if the motor can't get full voltage, it can't make full power. However, that's what "dither" and "load compensation" and any of the varous other terms that mean basically the same thing are for. Here's another place for experimentation. Too much dither or compensation and you can get jerky movement, too little and the slow speed running will be poor.
If it gets really crazy, and you can't remember what you did, there's always the factory reset, which in TCS decoders is programming a 2 in either CV08 or CV30.
Have fun, you can't hurt anything by goofing up with this, and if you DO goof up, the factory reset is our friend [:D]

--Randy

[Anonymous]

Changing speed values in a TCS T1

I have an inexpensive HO 0-6-0 switcher that I reworked to make it run better. I am now happy with the mechanical and electrical systems.It runs well.

I installed a TCS T1 decoder and left all the default values at the factory setting. I would like to set the the speed setting value to a more realistic yard speed. Currently top speed is to fast especially for the my grandson.

My question is this; what CV's should be changed to get a slower top speed at full throttle? Will this change adversely affect the pulling power of the loco?

According to the T1 literature the dither feature can be reset a different value. Would I gain anything by setting dither to 100% or less keeping in mind that this is a yard switcher.

Any comments or suggestion would be appreciated.

Great forum. So much good info

Joe

[chateauricher]

QUOTE: Originally posted by electrolove
BUMP again [:D]

Everything by Joe Fugate is so good. Can someone at Model Railroader please make Joe's awesome post appear at the top so we don't have to 'BUMP' them.

[#ditto]

I emailed Bergie ( a while back) and asked him to "sticky" all of Joe's Forum Clinics; but he still hasn't done it. [:(] [sigh] [:(]

[electrolove]

BUMP again [:D]

Everything by Joe Fugate is so good. Can someone at Model Railroader please make Joe's awesome post appear at the top so we don't have to 'BUMP' them.

[mecovey]

As a follow up to the Athearn problem - I phoned Toney's Train Exchange and talked to Ken. He suggested resetting CV29 to the factory value. I did and that reset everything tot he factory values. Thanks Ken

[fdmajor]

Many Thanks to everyone!

This forum has the QUICKEST responses I have ever seen. And the information is right on target. All this has been extremely helpful to me.

" I Love This Forum"

Hope all of you have a wonderful Day!

Don

P.S. I'm sure more questions will come, maybe later I will be able to pass along some tips to someone...
Thanks again to all who answered by questions. I'm headed over to buy the books suggested.

[mecovey]

Hi Joe,
Thanks for the speedy reply. As I understand it the decoder is indeed an MRC and I agree with your assessment as to its value. Do you know if there is a way to test the decoder or at least reset it?

When I first got the engine (one of two) it had decoder issues with respect to the headlight and I had to return it to Athearn. That saga is on another thread. I hate to go through that again if someone has a better way.

Michael

[jfugate]

Michael:

When I get wierd behavior like that, I first think "decoder issues". I'll swap decoders between locomotives and see if the problem travels to the other loco. If it does, then it's the decoder, no question.

I think the decoder in the Athearn is an MRC sound decoder, is it not? Unfortunately, MRC decoders leave a lot to be desired ... that's why I'm not especially fond of them, and prefer Digitrax, TCS, Soundtraxx, Lenz, and NCE decoders over MRC ones (in that order).

[ereimer]

fdmajor ...

think of the DCC bus wiring as the highway , and the track feeders as the offramps to get the power to your track

what you want to do (simplified) is run the bus wires under the layout following the outline of your track , then run feeders from the bus to the track . then the bus connects to the command station (booster)

am i answering your question ?
do you have 6 more questions now ? [:D]
to everyone else .... did i get it right ?

[mecovey]

I hope this question is appropriate for this topic...I run Digitrax and one of my engines is an Athearn Challenger. I have had it for about a year and it runs great. Tonight however, I was running it through a turnout that it had run through hundreds of times and it stalled. The marker lights started flashing and all sound was out from it and all of my other sound equipped engines. I assumed a short, shut off the power and finding none, turned the power back on. Everything came back up and ran as usual. About 30 minutes later as I was running the Challenger it suddenly changed directions for absolutely no apparent reason. It was as though the polarity had reversed on a straight DC engine. It still runs except the direction of travel is backwards from the indicated direction of travel on my DT-400. Also the headlight no longer operates nor does the backup light on the tender. If it was a BLI engine, I would try resetting everything to the factory defaults but that doesn't appear to be possible on the Athearn. I would really appreciate it if anyone could help me diagnose this problem.
Thanx, Michael

[jfugate]

Don:

In fact, I'd start with Basic Wiring for Model Railroaders by Rick Selby. Lots of pictures, and a good basic chapter on DCC to boot! Here's a link:
http://store.yahoo.net/kalmbachcatalog/12212.html

Just what the doctor ordered, if you ask me. Then get DCC made Easy if you want to move on up to more detailed DCC info, still with lots of pictures, though!

P.S. Rick's operated on my HO Siskiyou Line now and then ... and he's a *great* guy ... used to host the Student Fare column in MR.

[fdmajor]

Thanks jsalemi, for the quick reply.

I'm sorry, I'm so dumb when it comes to this DCC bus wiring. As much as I have read, I should be an electrical engineer by now. But still having trouble screwing in a light bulb! Ha, Ha.
A little laughter, to smooth my DCC induced headache...
Do you feel that the book "DCC Made Easy" is basic enough??? Does it have a lot of pictures and drawing???

Thanks again!!!

Don

[Anonymous]

Well, if you go to the online store here or your local hobby shop, you can get a Kalmbach book called "DCC Made Easy" that gives a pretty good grounding in the basics of DCC. And of course Joe has a DVD that you can buy through his website that sounds like it'll walk you through everything you need to know.

[fdmajor]

Hello Mr. Fugate,


I just finished building my 4'x8' benchwork. Plans was from the Model Railroader magazine.
I have plans to add a 26"w X 5'L, "L". Then add a 26"w X 12' L , "L" to that. (something in the end that looks like a "U".)
Am looking ahead to the wiring part. This will be a DCC layout and the control system will be EasyDCC. (I have read everything on your site, and this forum.)

My problems is; I have read so much about wiring for DCC ( for a little more than 5 months now) and I just can not get the basic understanding of what is going on.
I need a book, video tape, pictures (someone to hold my hand, I guess?) to be able to understand this.
Do you have ANY suggestions WHERE I need to start??? Remember, very basic stuff to start, then easy steps from then on. Does you video series start this basic???

I just go finished looking at your home site and found the drawing of "How I wire my track feeders for DCC"

It looks Great!!! But it's well above my head. I may be making this harder than it really is.

I'm OPEN for suggestions from you or any member of the forum. ANY assistance will be greatly appreciated...

Thanks for all of your help and time...

Don

[jfugate]

QUOTE: Originally posted by grayfox1119

I also agree with you Joe on electrical bullet-proofing the track system. Having worked in electronics field for 53 years, I have seen many times what poor connections and high resistance connections can do ...

grayfox:

I'm in computer software rather than hardware, but like you, I don't trust those unruley electrons! [swg]

[jfugate]

QUOTE: Originally posted by ereimer

to paraphrase my old boss....

i'd rather OVER DO the wiring than DO the wiring OVER

ere:

I'm gonna have to remember that one. [:D] That's *exactly* my sentiments!

[grayfox1119]

I also agree with you Joe on electrical bullet-proofing the track system. Having worked in electronics field for 53 years, I have seen many times what poor connections and high resistance connections can do. I actually witnessed a fire at one company when a high resistance connection between two dissimilar metals at a connector ( 220V 600A in this case) caused the entire box to be destroyed, lots of smoke too. Granted that we are talking about "flea" power here, bu the rules of electricity still stand fast. I like your method of soldering the rail joiners, I intend to do the same on my layout under construction now.

[ereimer]

to paraphrase my old boss....

i'd rather OVER DO the wiring than DO the wiring OVER

[jfugate]

I'm thinking that perhaps we could do a layout maintenance FORUM CLINIC one of these days ... and I agree, the one thing such a forum clinic will do, is cause a reality attack once you see what's involved in keeping a large layout going.

[Anonymous]

Joe,

I would actually love to hear what kind of maintenance is required for a layout your size.

I'm a small layout guy myself, but I'm of course a "closet fan" of layouts like yours. I scanned your Mushroom article from the late 90's into my computer and browse over it occasionally just to "dream". Darnit, I seem to not have your first installment, my scanned images start at the 2nd installment.

In any case, having never been involved with a club, etc., I have no idea how much maintenance is required for a larger layout. Would be very interesting information to share.

You've done this for years and years, and know what's required (sounds like you have a crew that helps out, etc.). Sometimes when I see people designing their first layout and it's huge, I often wonder if they know what sort of maintenance it will require.

That sort of information could be a good reality check for those who start planning based on the larger layouts they've seen in the magazines.

[jfugate]

All the discussion around bus wire and feeders involves a lot of issues, preferences, and so on. We could run an entire FORUM CLINIC just on that one area.

One issue around your bus wire and feeders is the fact that nickel silver rail is not as good a conductor over distance as is copper wire. If you look at the ohms per foot of nickel silver rail, you will quickly realize that placing feeders farther apart than every 20 feet or so will cause problems because of the resistance of NS rail, especially smaller code rail and high current levels ... which is just what you get with DCC and scale rail sizes.

So then you need to consider how big the bus wire needs to be to get no more than say, a 5% voltage drop from one end of the layout to the other. Here's a chart that I posted earlier in this clinic that's based on 12 volts and 3.5 amps:

Length of run for no more than 5% voltage drop
16 guage – 20 ft
14 guage – 35 ft
12 guage – 50 ft
10 guage – 80 ft

The common reasoning as to track feeders is to not rely on rail joiners to carry the power from rail section to rail section because of dissimilar metals, corrosion, gunk from scenery work, etc ruining the conductivity of the joint. You can solder rail joints, but if you do that too much, you hinder the tracks ability to "breathe" with the roadbed and benchwork as it expands and contracts because of seasonal changes in temperature and humidity.

So if you want ultra-reliable track power to your locos, you run a feeder to every rail section (typically every 3 feet) and avoid soldering rail joiners. This easily gets around the poor conductivity issues of nickel silver rail and rail joiners losing conductivity with time -- and prevents the rails from popping off the ties because of an expansion/contraction problem.

This said, I do solder a few rail joints:

1. Any track section shorter than one foot gets soldered to an adjoining section that has feeders attached to it.
2. I solder the rail joiners on a turnout's point end to the adjoining section that has feeders attached to it (consistent with the general rule of feeding turnouts from the point end).
3. I solder the rail joiners on two 3-foot flex track sections to make a 6-foot section when I lay track on curves, this helps the track flow smoothly with fewer kinks.

Some may feel feeding every track section with its own feeders is overkill, but I prefer to make the electrical part of the layout as bullet-proof as possible, so I can enjoy ultra-reliable track power.

Then all I have to worry about is keeping the track clean. Now layout maintenance is a whole different FORUM CLINIC ... [swg]

[jfugate]

QUOTE: Originally posted by wiking2

I just talked to NCE and they say that the powercab is due to come out at the end of September or erly October.

Thanks, wiking, for the update!

[Anonymous]

I just talked to NCE and they say that the powercab is due to come out at the end of September or erly October.

[rrinker]

That's a rather contrived example, but say it was that - three 4x8 ovals. I would put the booster in the middle front of the middle table. Each table woudl have a bus loop following under the track - not just a single bus down the middle. At the edges where the tables meet - a simple jumper from one bus loop to the one on the next table. At the back edge of the tables, the bus lines do not have to connect to form a complete loop. At the risk or resurrecting THAT debate, I will say that i did NOT close the loop on my layout. I have three bus loops runnign around my 8x12 section - one for the outer main, one for the inner main, and one for the yard and switchign areas on the inside. It's really 6 because each one is split at the far end, but I have the left and right halves of each bus connected to the same terminals of a terminal strip. Maybe overkill, but my trains do not slow down, the lights do not flicker, etc.

--Randy

[Anonymous]

I'd say don't run the bus arbitrarily. Run it sort of along the track. There's no point in bus where there's no track just to be symmetric. Also, in a large layout some kind of star configuration for the bus might make sense. There are lots of ways to do it, and fortunately, most of them will work!
It is very desirable to keep the feeders short, though. Feeders small enough to hide are going to add up resistance wise. Also, it seems to me that longer feeders are going to have a better chance of getting snagged and damaged.

[grayfox1119]

Randy, one thing that I see can be somewhat confusing to people. Lets say that you have three 4x8 tables in a row. Now you run a power bus underneith at midpoint, which of course would be 2 feet from either end of the boards. Now you have tracks on the top side that may be running 6" in from either side of the tables. You will be more than 12" away for the track drops to reach the power buss. Personally, I don't see this as being an issue, especially if you are running #14 wire for drops, and are placing drops every 3 feet. Thoughts?

[rrinker]

Like everythingelse - it depends! It depends on how long they will be, because the longer the wire, the more voltage drop there will be. But, the BIGGER the wire (smaller number in wire gauge terms - #12 wire is BIGGER than #18), the less loss there will be. There is a point of diminishing returns, otherwise we'd all use big heavy 00 wire, but good luck pullign that through holes in your benchwork.
It also depends somewhat on your modelling scale. The more current draw, the greater the loss, so with O and G scales you usually need heavier wire than N and Z scales, although this can be offset somewhat by the fact that in the same space you can have a lot more running N scale locos than G scale locos.
All that and I still haven't told you what wire size to use. Well, for amaller runs in the smaller scales, say a 4x8 HO layout, you can get away with #16 or even #18 without too much trouble. For runs up to 25 feet or so, use #14. Anything longer, use #12. If you need to run wires more than 50 feet, consider distributing your boosters - remember that over 50 feet you actually have 100 feet of wire, and even #12 will start showing noticeable voltage drops.
Now, you can't really solder #12 to your track, well, you can, but it won't be pretty. But over short distances (most track feeders are 1 foot or less), using thinner wire won't hurt anything. For HO I use #20 wire for my feeders, for N I'd use #22 or #24. For O and G, #18. Have plenty of feeders - the point of the wire bus under the layout is because the rails are a smaller size conductor, plus rail joints are not reliable power connections. So if you run a nice power bus under the layout but only connect a set of feeders every 20 feet, you are defeating the purpose.

--Randy