Are bus wires & feeders necessary?

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cptjamescook

New Member
I am building a simple 40 foot loop DC HO model railroad using Atlas code 100 nickel-silver track. I am wondering if resistance will be a problem if I don't use a bus wire and feeders. The train will never be more than 20' from the power source (right?). I plan to solder the track connections. I plan to run a single engine w/maybe 12 cars max. My power source is a Silvine transformer with a 15 V DC output.

I want this to be a very simple set-up: One train on the track going around a 40' loop (no switches).

Do I really need the bus wire and feeders?

If I put an additional feeder half way around the loop then no train would be more than 10' from power (right?)
 

flh80

Member
You could get by with just running one set of power feeds down to the other end. The only thing that happens is the train slows down with less power.

Back in the day before DCC, another reason was that people had more feed wires were to make separate blocks to run locomotives independantly from others. If your not going to block it, then you don't need as many feed wires and as long as all the joints are soldered.
 

Selector

Well-Known Member
If you are in DC operations, probably not so huge a deal...although I'd bet dollars to donuts you'll notice a drop in performance at the far ends of a loop that size. And that's if your joiners all work properly, and all your routing done by turnouts....every single one. The odds are good for you initially, but within a couple of weeks, all bets are off. ;)

DCC, though, is another matter entirely. If your system won't respond quickly during a quarter test halfway around your loop, it means the signal to noise ratio is too high and it can't detect a fault. Decoders are going to be looking over their shoulders a lot. :eek:
 

Beachbum

Member
Yeah, I think you'll see a performance drop even with no turnouts.

Have you considered using terminal joiners every few feet? A bit more expensive than soldering wire feeders but you can just drop 'em down and connect to a bus if and when needed. I think that would be easier than trying to retrofit feeders.
 

OCN Guy

Member
so... what's the consensus? Bus or no bus? And if bus... how do you wire one? I was about to wire my layout with feeders to different areas just to make sure all areas got power.
 

fast_ian

Member
so... what's the consensus? Bus or no bus? And if bus... how do you wire one? I was about to wire my layout with feeders to different areas just to make sure all areas got power.
FWIW;

- I used "suitcase connectors" to tap the feeders into the bus - Easy, and no soldering required.
- I believe consistent power is *much* more important with DC than DCC - With the former, you're feeding a very low voltage to the rails when you want to go slowly. With DCC you've got a nice "high" voltage on the rails at all times.

My 02c is therefore to "do it right" the first time and avoid frustration later.

Cheers,
Ian
 

TomR

Member
I am building a simple 40 foot loop DC HO model railroad using Atlas code 100 nickel-silver track. I am wondering if resistance will be a problem if I don't use a bus wire and feeders. The train will never be more than 20' from the power source (right?). I plan to solder the track connections. I plan to run a single engine w/maybe 12 cars max. My power source is a Silvine transformer with a 15 V DC output.

I want this to be a very simple set-up: One train on the track going around a 40' loop (no switches).

Do I really need the bus wire and feeders?

If I put an additional feeder half way around the loop then no train would be more than 10' from power (right?)
I agree with this statement:

Secondhandmodeler
If you solder the joiners then I wouldn't worry about it. The speed drop off on the far side will be barely noticeable.
I actually made voltage measurements under load, and most of the problems I measured were with joint resistance. The rail itself had negligible resistance compared to the load. The load of a single engine is next to nothing in respect to the resistance of the rails over 20 feet of distance.

If you had a forty foot closed loop with no insulated joints, you would have equal or less resistance than two 20 foot tracks in parallel at any point in the system. I doubt you would see any performance change with good joint connections and only one locomotive.

Tom
 

fast_ian

Member
...I doubt you would see any performance change with good joint connections and only one locomotive.
+1 For sure.

However, the potential "curve ball" is the age old expansion/contraction problem - If all joints are soldered, and depending on the environment, rail kinking may become an issue.

I hasten to add I'm in a nice temperate climate and haven't seen the problem, but those in basements that aren't heated all the time report nightmares and the need to gap the rails regularly.

As always, my 02c, YMMV,
Cheers,
Ian
 

cptjamescook

New Member
I thought about the expansion/contraction issue. Read somewhere that it is not really a problem. Someone who did the engineering/calculations and tested.

Has anybody had an experience with buckling track?

You would have to plan "measured gaps" in the track layout at specific temps to compensate for the highest temp that would be experienced - right? I have not heard of this, as every body tries for seamless/smooth track joints.

Has anybody had an experience with buckling track due to extreme temp changes?

This layout is going in a public room that will have temp chgs.

Thanks for everybody's input.
 

OCN Guy

Member
Can someone post a picture of soldering track joiners? I don't want to goop up my track when all my back ordered pieces finally get here and I can stop living in limbo :mad:
anyway, does anyone have a pic of soldering joiners, or an article on how to do it properly?
 

TomR

Member
If it is a problem, one could always solder most joints and just occasionally use a slip joint....bridging that joint with a short thin wire below the board.

That's what they do on the real stuff.
 

TomR

Member
Can someone post a picture of soldering track joiners? I don't want to goop up my track when all my back ordered pieces finally get here and I can stop living in limbo :mad:
anyway, does anyone have a pic of soldering joiners, or an article on how to do it properly?
I can do an article, I suppose, if there isn't one.

The key to soldering is a big pencil that is hot, a clean metal surface, and active rosin flux with 60/40 wire solder.

Use a heavy wide tip, tin it with a two or three pin-head size dot of solder, and lay the blunt side with the solder dot against the rail joint.

Touch the fresh wire solder to the rail, NOT the tip.

I also lay a wet sponge on my rails on either side of the joint. This prevents heat from traveling down the rails and loosening the plastic that holds the rails in place. The layout I inherited looks like the fellow soldered with a hot dirty rock. :)

I do electronic design and at a few points managed manufacturing of panel meters, automotive and marine equipment, and communications equipment. We often had to solder to studs or connections through low temperature materials like plastics, and the wet sponge trick always worked well when properly applied.

The key to soldering around plastic is enough power in the soldering tip to keep temperature up, CLEAN joints, good active rosin flux, and a low temperature solder. Get in, get it hot quick, flow the solder, and get out with the heat as soon as it flows....and don't wiggle the joint while it cools. A wet sponge is a lifesaver for melting down the plastic and loosening the rails.


Tom
 
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LoudMusic

Member
You could always try it without feeder/bus wiring and add it later if needed. It's not like it's a huge undertaking to drill a tiny hole next to the rail and drop a wire in.
 

Selector

Well-Known Member
If you are using wooden framing for the layout, it won't be temperatures that will cause buckling of your rails. It will be the wood either drying or getting more humidity in it, depending on the orientation of the tracks relative to the orientation of the lengths of milled lumber and its grain.

Code 100 nickel-silver rail 100 feet long, no gaps, will expand about 1/4" over its contiguous length with a rise in temperature of 30 degrees F. Hardly anything, and certainly manageable with three or four 1/16" gaps. However, one must chose his gap locations wisely, and that is the rub.

Track deflections are much more likely to take place due to drying. When the grain expands due to higher humidity, the tracks should want to pull apart. When they dry, the timbers shrink, and the tracks want to close up with the shrinking...gaps close and the rest that follows is easily imagined...or experienced.
 

cptjamescook

New Member
I am going to use 3/4 birch plywood (painted) in an around the room shelf layout. The total length will be 42'. The plywood should be pretty stable.
 




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