Simple power question...

[myoung5655]

I recently bought a kato starter set, then added an inner track, a crossover, and a Rail Yard Switching Track Set off of the outside line.  On the whole, the set has two feeders, one for the outside track, and one for the inside.

 

I then equipped the set with DCC.

 

I'm wondering if a set of this size would want a separate feeders around the track, branched off of the same power supply.  I would imagine that you pick up some resistance in the unitrack interconnect that would affect power.    What's the conventional wisdom for inserting power feeders into a track layout?

[brill27mcb]

If by "crossover" you mean the Kato double crossover (sort of X-shaped), be aware that track power is not carried through on the straight tracks. That means the power at the far end of the double crossover from your power supply point has to go all the way around the loop to get there. You might experience voltage drop (a bit at each rail joint and turnout around the loop, which eventually adds up). The train speed will be uneven and as it passes over the double crossover it might dramatically speed up (or slow down, depending on direction). Many Kato users recommend having power feeders on all four approaches to the double crossover for this reason.

 

Rich K.

[CaptOblivious]

Rich, good to know!

Aside from that issue, I haven't personally had voltage drop issues running 8-10ft loops of Tomix track off of one feeder with DCC. FWIW.

[myoung5655]

Thanks for the input guys.  I'll pick up new feeders and wire them in.

[KenS]

I have an oval of unitrack double-track about sixteen feet end-to-end, which makes for around 39 feet (12m) of track. At one time I only had one feeder per track, and a double-crossover about eight feet from it, so at the crossover trains were going from ~31 feet of power loss to 8 feet of power loss, a difference of about 23 feet (around 7m). My track was in good, but not perfect condition, and I saw a significant change in train speed when the motor unit crossed the insulator at the crossover. Enough of a change to be very noticeable and annoying to me.

 

Power loss in nickle-silver rail is much higher than in copper wire to begin with. Power loss across unijoiners (or other sectional track joiners that depend on friction contacts) only makes this worse. DCC in and of itself won't change anything, but loss goes up with current, and so if you use DCC to run multiple trains on the same track (or double-head locos) as you increase the current with more trains, you increase the amount of loss. 

 

I don't think you need extra feeders for a table-top layout or a typical starter set, particularly if you're setting it up for temporary use. The minor benefit you might gain likely isn't worth the extra work each time. Even for mine the speed change was only a minor annoyance, not a major problem. But the usual rule of thumb is to have feeders every six feet or so (2m) even without sectional track issues, to ensure you don't have noticeable loss. That's likely overkill, but if you're designing a permanent layout, it's still good advice.