Question for Neil B. or whomever

[KeithL]

I've enjoyed following Neil Besougloff's series in CCT on building the Coal Terminal & Trestle Railroad. The wiring plan that Neil describes in Part 3 (February 2004) brought to mind a question:

Neil has power feeds to each of the track blocks. I notice that no return feeds are indicated. I realize that return feeds are not absolutely necessary because only the center rail--not the outer rails--in each block is isolated. I wonder, however, strictly from the standpoint of avoiding voltage drops (i.e., apart from signal strength issues related to the potential use of DCS), if it helps to have a return feed as well as a power feed to each block? Actually, my question would be the same whether we're talking about powering electrical blocks or simply putting feeder wires at intervals around a non-blocked loop to maintain voltage.

Bottom line: do return feeds help avoid voltage drops, or do power feeds alone do the job as well as it can be done (again, apart from issues related to the use of DCS)?

Happy New Year![:)]
Keith

[Big_Boy_4005]

I come from the school of overkill.

On my layout, which is very large, I place a center rail (hot) feed, and an outside rail (ground) feed, on every 3 foot section of Gargraves track. In addition, I place a third wire on the other outside rail, for use in a train detection system. Because only one rail is being used as ground, I like to make sure I have a good path. I'm sure that you could get away with much less.

It has worked well in the past, but I haven't tried it yet with TMCC, and even with a good path, I'm not sure how far that signal will travel and still work properly.

[lionelsoni]

I'm in the opposite camp. I solder all my rail joints, use no feeders, and have no problems with voltage drop.

[Big_Boy_4005]

Bob, it is very difficult to solder Gargraves blackened center rail, as I reminded myself today by trying to solder two leads onto a cluster of switches. The outside rails are no problem, but with over 20 cases (over 3000 feet) of track being laid, and many insulated connections, soldering seemed impractical.

I use 3/8" crimp on tab connectors and shove them up the bottom of the rail, under normal circumstances. The concept was actually modified from a Marx version of a lockon. This method was used in a public display that used a computer to control the trains, and was chosen partly for its redundancy. I am still using this method on my layout today.

[KeithL]

Does anybody know if, from an electrical standpoint, additional return feeds help maintain voltage, or do only additional power feeds help? In other words, is it sufficient to have power feeds every so often, or, for optimal voltage maintenance, should I have a return feed along with every power feed?

[Big_Boy_4005]

Sorry for getting off topic and not answering your question. The simple answer is: YES, additional return feeds do help, and here's how.

Resistance is the key. Every material, even conductors like copper, gold and steel have some resistance to the flow of electricity, just in different amounts. Electricity always takes the path of least resistance. The further the electricity has to travel, the more resistance it encounters.

Imagine that the center rail is a hose with water coming out, and the outside rail is the drain. Place the hose near the drain, no problem. Adding feeders to the center rail is like moving the hose (not adding more hoses, because the volume of water stays the same). As the hose gets further from the drain, the system becomes less efficient. So, it follows that adding drains helps keep things flowing well.

The next question is how far between feeder and return sets? That depends on your track, and how large your blocks are. Bob's method of soldering rail joints ensures better flow through what can be a source of high resistance, thereby allowing greater distance between feeder sets. Because of the type of track I use, I perfer not to worry about track joints, and wire around them.

[KeithL]

Elliot and Bob--thanks for your help![:)]

[Anonymous]

Hi Keith,

As far as the 4 x 8 layout in the February issue of CTT, the power feeds to the three blocks (two sidings and a portion of the elevated track) are simply to turn the power on and off to those areas. There are two other lockons on the layout with both power and return wires, which is plenty enough to keep the voltage up on this small layout. Keep in mind too that because this layout is so curvy, the O-27 trains that can run on it will never be pushed to their maximum capacity.

Return wires could be added to the three blocks, however, if desired.

The post by "Big Boy 4005" just above does a nice job of answering your track feed question. As far as DCS goes, if you know from the outset your layout will use DCS, it's best to wire the layout the way MTH suggests. There is no negative effect on TMCC.

My home layout was built before DCS existed. I've since added DCS to my bus-wired layout, and although my signal strength isn't all "10", everything works just fine.

Sincerely,
Neil Besougloff
editor, Classic Toy Trains