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Continuous bus wiring for DCC?

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Posted by richhotrain on Wednesday, September 15, 2021 1:40 PM

gregc
 
richhotrain
Now, as I suggested to the OP, if that concerns him, then cut the bus wire midway around the layout, so he will now have two powered sets of bus wires. 

it's not clear that you fully recognize that there are actually two parrallel loops with feeders interconnecting them, one composed of the bus wires and the 2nd the track itself.

OMG, I am about to totally give up here. After completing 5 different large layouts over the past 17 years, is this what it has come down to???

I don't recognize that "there are actually two parallel loops with feeders interconnecting them"???

What has happened to this forum? 

I need to stop answering questions and trying to help people and leave it to the self-appointed "experts".

Rich

 

Alton Junction

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Posted by gregc on Wednesday, September 15, 2021 12:33 PM

richhotrain
Now, as I suggested to the OP, if that concerns him, then cut the bus wire midway around the layout, so he will now have two powered sets of bus wires.

it's not clear that you fully recognize that there are actually two parrallel loops with feeders interconnecting them, one composed of the bus wires and the 2nd the track itself.

yes the track may not be fully connected because of faulty rail joiners, but you could probably cut the bus wire in more that 1 place and the layout would probably still work because the track itself bridges the cut in the bus wires.

would putting "snubbers" at each end of the wire bus make sense

that's all Mike was pointing out

 

as an aside, we were puzzled yesterday why a loco was still powered when the lamp used as a power limited was removed.   we were worried that somethign was miswired.   is just so happened what the metal wheel of a car was bridging the gap isolating the two power districts.

greg - Philadelphia & Reading / Reading

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Posted by richhotrain on Wednesday, September 15, 2021 11:42 AM

It probably makes more sense to a DCC operator. But, you seem sincerely interested, so let me take another shot at this.

When a DCC operator is ready to install bus wire, if he decides upon a continuous loop, he will take a pair of bus wires and insert them into the two ports on his DCC booster.

On an HO scale layout, the wire will often be 14 gauge copper wire. He will strip about 1/2 inch of plastic insulation off the end of each bus wire and insert it into the booster port. Usually, only one wire will fit into the port.

So, if the DCC operator decides upon a continuous loop of bus wires, he will likely trace the bus wires under the layout directly below the track on top of the layout. When he completes the loop by arriving back at the booster, it can either terminate there or connect into the two wires coming out of the booster port by forming 3-wire pigtails held together in plastic wire connectors. It is 3-wire because each wire coming out of the booster must be cut in order to join the continuous loop of bus wire. Thus, the entire continuous loop of bus wires is powered.

Now, as I suggested to the OP, if that concerns him, then cut the bus wires midway around the layout, so he will now have two powered sets of bus wires. On a small layout, there may be no real benefit. But on a larger layout, it will minimize voltage drop.

Alton Junction

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Posted by richhotrain on Wednesday, September 15, 2021 6:03 AM

jjdamnit

It is possible to run multiple locomotives, which may exceed the limitations of the power booster, on a small pike which could cause power fluctuations.

If the total current draw (amps) of all running locomotives exceeds the power limitation of the booster, the booster will shut down. 

Rich

Alton Junction

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Posted by richhotrain on Tuesday, September 14, 2021 4:25 PM

WilScarletMacaw
richhotrain

Good points. I'll start another thread on that.

Excellent. I will follow it once you do.

Rich

Alton Junction

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Posted by WilScarletMacaw on Tuesday, September 14, 2021 4:21 PM

richhotrain

 Good points. I'll start another thread on that.

 
WilScarletMacaw
While my layout has been running with them connected for over 10 years, this year I have some type of electrical problem that resets my NCE Power Cab as I try to accelerate the engine. So even with my short line, I may add snubbers. Can't hurt. I'm trying to avoid ripping up my almost complete layout and starting over. 

 

 

Well, agreed, it can't hurt to add snubbers, but it wouldn't hurt to have a reason to do so.

 

Check out this website by the highly respected Mark Gurries. He presents a comprehensive discussion of snubbers and the signs of when you may need snubbers on the track bus.

https://sites.google.com/site/markgurries/home/dcc-general-best-practices/wiring-planing/snubbers-rc-filter

Meanwhile, you have thrown a curve ball into this discussion with the comment that you have some type of electrical problem that resets your NCE Power Cab as you try to accelerate the engine. Whether or not snubbers can resolve this problem is beyond my pay grade. It might be worthwhile to start a new thread on that issue.

One final thought. If you are concerned about a continuous bus wire around the layout, just cut it so that you have two shorter non-continuous bus wires.

Rich

 

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Posted by richhotrain on Tuesday, September 14, 2021 3:29 PM

gregc

rich

if you break the bus, couldn't it still be electrically connected thru the track 

Sure, because both of those "broken" bus wires remain connected to the lead bus wires that are connected to the booster.

Rich  

Alton Junction

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Posted by gregc on Tuesday, September 14, 2021 3:11 PM

rich

if you break the bus, couldn't it still be electrically connected thru the track

greg - Philadelphia & Reading / Reading

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Posted by richhotrain on Tuesday, September 14, 2021 2:56 PM

You're confused. I referred to a "continuous loop of track", not the OP.

And no one referred to "the other side".

Alton Junction

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Posted by richhotrain on Tuesday, September 14, 2021 11:05 AM

Lastspikemike

Cutting just the bus wire loop wouldn't break the electrical loop unless a point in the layout were to be double gapped also, at the same spot electrically speaking. The bus is just a parallel circuit to the circuit formed by the rails.  

I don't know what you mean by "break the electrical loop". The OP initially asked...

WilScarletMacaw

Is there any advantage to connecting the ends of the bus lines for a continous run circle on a DCC layout, or should the terminal points just be left alone? 

My response to the OP was a simple assurance that if he is concerned about a continuous bus wire around the layout, he could just cut the continuous bus wire so that he has two shorter non-continuous bus wires. 

But, as I and others have mentioned previously, a continuous loop of bus wire is no more harmful than a continuous loop of track. In other words, there is no adverse effect. I had a continuous loop of bus wires for 13 years without adverse effect on my old layout.

That said, what is a continuous loop of bus wire? A bus wire, or more appropriately a pair of bus wires on a DCC layout, is typically a pair of heavy gauge (e.g., 14 gauge copper wire) wires connected to the DCC booster. If that pair of wires forms an unbroken continuous loop around the layout, it has to end somewhere.

Most often, it cannot return directly to the booster because the ports on the booster won't be large enough. So, a continuous loop of bus wire must tie back into the wire that is connected to the bus. If that is a concern, then cut the bus wires halfway around the loop and wind up with two equal, but shorter lengths of bus wire. That is often recommended on larger layouts to avoid, or at least minimize, voltage drop.

 

Alton Junction

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Posted by richhotrain on Monday, September 13, 2021 4:00 PM

WilScarletMacaw
While my layout has been running with them connected for over 10 years, this year I have some type of electrical problem that resets my NCE Power Cab as I try to accelerate the engine. So even with my short line, I may add snubbers. Can't hurt. I'm trying to avoid ripping up my almost complete layout and starting over. 

Well, agreed, it can't hurt to add snubbers, but it wouldn't hurt to have a reason to do so.

Check out this website by the highly respected Mark Gurries. He presents a comprehensive discussion of snubbers and the signs of when you may need snubbers on the track bus.

https://sites.google.com/site/markgurries/home/dcc-general-best-practices/wiring-planing/snubbers-rc-filter

Meanwhile, you have thrown a curve ball into this discussion with the comment that you have some type of electrical problem that resets your NCE Power Cab as you try to accelerate the engine. Whether or not snubbers can resolve this problem is beyond my pay grade. It might be worthwhile to start a new thread on that issue.

One final thought. If you are concerned about a continuous bus wire around the layout, just cut it so that you have two shorter non-continuous bus wires.

Rich

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Posted by snjroy on Monday, September 13, 2021 3:47 PM

Impressive... I guess I was assumming a single loop.

Simon

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Posted by jjdamnit on Monday, September 13, 2021 3:25 PM

Hello All,

snjroy
I can't imagine you running more than 4 engines on such a small loop.

 

On my 4'x8' pike I run a consist of four (4) GP40s, and a consist of three (3) GP30s simultaneously.

A 44-tonner, 70-tonner, GP38-2, and an RS-3 are used for switching operations while the two (2) consists are running. 

I use the NCE 5 Amp wireless system.

Track power is not through a bus. Track power, from the command station/booster, goes to a barrier strip.

From the barrier strip, track feeders radiate out.

The entire pike is protected by a single EB1 between the command station/booster and the barrier strip.

An MRC AD 520 auto-reversing unit powers the wye.

It is possible to run multiple locomotives, which may exceed the limitations of the power booster, on a small pike which could cause power fluctuations.

Until we hear back from the OP it's all speculation and presumption.

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by snjroy on Monday, September 13, 2021 2:48 PM

I'm no expert but I can't see how a bus line, connected to form a circle, and feeding a 14 foot loop, could cause running issues. I can only see benefits as mentioned by others.  And I can't imagine you running more than 4 engines on such a small loop.

What do you mean by the system "re-starting"?  Would that mean that there is a short? If that is the case, you need to hunt that down. I would start by removing all the engines on the track, and checking the engines one by one and seeing what happens as it goes through the layout. It could also be a piece of rolling stock shorting in the switches. 

Simon

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Posted by jjdamnit on Monday, September 13, 2021 2:32 PM

Hello All,

WilScarletMacaw
I can't recall exactly when I bought my NCE Power Cab, but it was probably before 2010...I've been able to use my Power Cab successfully with my DCC locomotives on a simple circle of EZ track...

OK, knowing what DCC system you have and its age helps immensely.

According to the NCE website, "This 2 Amp system can operate up to 4 HO locomotives or 8 N scale locomotives running at the same time."

Has anything changed as far as power consumption- -have you added any locomotives or powered (lighted) cars lately?

Do your run DC and DCC locomotives simultaneously; even having the DC units parked on "live" track?

WilScarletMacaw
I have to suspect the over 10 year old wiring on my layout.

I'm not suggesting that it isn't the wiring.

However, unless you live in a highly corrosive environment and the pike has been stored outdoors I suspect it might be something else.

Your Power Cab might be due for an upgrade. Check out this link...

What Power Cab Version Do I Have.

WilScarletMacaw
I actually have four sidings which are have DPDT switches so that they could be turned off during DC days.

What you are describing now is more than just...

WilScarletMacaw
...(A) simple circle, about 14 feet.

The DPDT switches could be suspect. But if they were only used for block selection of the sidings they might not be the reason for...

WilScarletMacaw
...some type of electrical problem that resets my NCE Power Cab as I try to accelerate the engine.

Not knowing how many locomotives you are running and if they are sound equipped or not, I suspect you have exceeded the 2 Amps of the system.

Have you tried running only one locomotive on your "mainline" with no cars and without using the sidings, testing only one unit at a time (having removed all other powered units from the pike)?

Does this happen with all the locomotives or only one specific unit after testing?

Now, knowing more details on your particular situation can help the great folks on these forums.

Do you clean your track?

How often?

By what method? (Without opening the "Track Cleaning" can of worms debate.)

Thank you for your answers.

All of your responses have helped create a better picture of your situation.

Keep the answers and questions coming and...

Hope this helps.

 

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by WilScarletMacaw on Monday, September 13, 2021 11:07 AM
Sorry everyone! I did not realize that Quick Reply would not quote the original message, so as a result my responses make no sense! Just know that I am very appreciative that you all took the time to give me some advice. Thank you!
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Posted by WilScarletMacaw on Monday, September 13, 2021 11:03 AM

SeeYou190
 

Thanks.

 

 
gregc
It would reduce the wire resistance by half at the mid-point and presumably reduce reflections.

 

The DCC guru, and electrical engineer, I know has told me that on a large layout connecting the bus into a loop is advatageous for exactly the reasons Greg mentioned.

In actual application, I think Rich said it best. There will probably be no noticeable advatage.

-Kevin

 

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Posted by WilScarletMacaw on Monday, September 13, 2021 11:02 AM
Thanks. I actually have four sidings which are have DPDT switches so that they could be turned off during DC days. I'm currently checking all connections to see if they are solid.
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Posted by WilScarletMacaw on Monday, September 13, 2021 11:01 AM
Thank you for your detailed reply. I can't recall exactly when I bought my NCE Power Cab, but it was probably before 2010 and when people began to recommend twisting the bus wires or using snubbers. Since I've been able to use my Power Cab successfully with my DCC locomotives on a simple circle of EZ track, I have to suspect the over 10 year old wiring on my layout.
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Posted by WilScarletMacaw on Monday, September 13, 2021 10:57 AM
Thanks
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Posted by WilScarletMacaw on Monday, September 13, 2021 10:56 AM
Correct.
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Posted by WilScarletMacaw on Monday, September 13, 2021 10:55 AM
While my layout has been running with them connected for over 10 years, this year I have some type of electrical problem that resets my NCE Power Cab as I try to accelerate the engine. So even with my short line, I may add snubbers. Can't hurt. I'm trying to avoid ripping up my almost complete layout and starting over.
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Posted by WilScarletMacaw on Monday, September 13, 2021 10:51 AM
Thanks.
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Posted by WilScarletMacaw on Monday, September 13, 2021 10:50 AM

It's a simple circle, about 14 feet.

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Posted by gregc on Monday, September 13, 2021 6:57 AM

betamax
So there are no devices that use the DCC/RailSync that would plug into the front (or side) jacks.

thanks for the clarification and describing the locations of the connectors.   (another learning experience)

can't imagine any devices other than boosters or possibly stationary decoders that would connect to the Railsync bus.

greg - Philadelphia & Reading / Reading

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Posted by betamax on Monday, September 13, 2021 6:28 AM

gregc

thanks for the explanation.

is the reason they include the Railsync signal in the fascia panel bus to connect the command station to boosters?    or are there DigiTrax devices that plug into the fascia panel that actually use the DCC data?

 

 
RailSync is present on the LocoNet cable, and passes through the rear jacks on the utility panel.
 
The front and side jacks are LocoNet T connections for throttles, and lack the RailSync signals. Those connections are only used to power throttles. The rear jacks are LocoNet B (Booster) connections.
 
So there are no devices that use the DCC/RailSync that would plug into the front (or side) jacks. Boosters and the like must be connected to the rear (LocoNet B) jacks.
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Posted by MrMe on Sunday, September 12, 2021 10:54 PM

The answer is, both!

On a given layout**, there is usually only a single LocoNet instance. That LocoNet will connect the command station, additional boosters, BDL168's and whatever other devices need Railsync, as well as wired throttles***, your LocoNet interface device (PR3, PR4, LocoBuffer, etc) and other devices that don't need it. Various iterations of the UPx (fascia) panels available over the years have various combinations of jacks that do/don't propogate Railsync, so you need to have an idea of what you can plug where and still have it work.

**Some VERY large layouts run multiple LocoNets, separating different types of traffic (For example, throttle and booster on one and signaling on another), along with something like JMRI to logically bridge them. But since the LocoNet is event-driven rather than polled, and runs at roughly 19,200 baud, that's rarely needed.

***If you have batteries in your wired throttles, and/or provide external power via the UPx's, the throttles will use that power instead of drawing it from the Railsync lines.

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Posted by gregc on Sunday, September 12, 2021 7:32 PM

thanks for the explanation.

is the reason they include the Railsync signal in the fascia panel bus to connect the command station to boosters?    or are there DigiTrax devices that plug into the fascia panel that actually use the DCC data?

greg - Philadelphia & Reading / Reading

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Posted by CSX Robert on Sunday, September 12, 2021 4:47 PM

Yes, they use Railsync to connect the command station and boosters.  Railsync is the DCC signal before it gets boosted to track voltage and current.  Loconet uses six wires, two for ground, two for Loconet data, and the last two are Railsync, the differential DCC signal.  When you plug a throttle into a Loconet fascia panel, if the throttle does not have a battery and the panel is not powered separately, the throttle will use the Railsync lines for power.  If you plug in too many throttles, you can place too much load on Railsync.  By powering the fascia panel separately, the throttle draws its power from that power source instead of Railsync.  While this does prevent the throttles from overloading Railsync, it is not boosting it.

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