### DCC Feeder Spacing

greenspun.com : LUSENET : Wiring for DCC : One Thread

I'm new to DCC and am building a new N-scale layout ("L" shaped, approximately 11' by 11') and will be running with the Digitrax Zephyr and 2 new MRC Tech 4 Model 200's for Jump Port Throttles. The Zephyr will feed 4 of Tony's Powershield circuit protectors (1 each for 2 parallel mainlines and 2 yards), and 2 of Tony's auto reversing units for the 2 reverse sections in my track plan. Each of the 2 mainlines are about 70 actual feet long.

Now the question: After reading Alan's excellent web site, and many other sources, I think I've got a general understanding of many of the principles. However, Alan states that for Code 83 track (HO I presume), feeders are recommended every 6 feet. This means, I think, that no spot on the track is more than 3 feet from a feeder. In a yard ladder situation, where 8 parallel tracks are each 3 feet long, is a single feeder at the throat of the yard sufficient, in that any point in the yard is essentially no more than 3 feet from the one feeder? In this case, there are some 24 feet of track being served by a single feeder, but no place in the yard is more than 3 feet from the feeder. Or, does each of the 8 yard tracks (each being 3 feet long) need its own feeder?

Soldering is not my strong suit, so I'm hoping that the real issue is purely one of resistance from the source (the feeder) to the furthest point away from the source, the end of any given 3 foot yard track. Or, does the total resistance of 24 feet of track (8tracks*3feet each) factor into the equation, and, thus, require a separate feeder per track?

Now, I'm not planning to build an 8 track yard with only 3 foot tracks in it, but the answer will definitly help in my understanding of the issues.

Thanks for any help to this newbie!

Mike McGavran

-- Mike McGavran (mcgavran@formula.com), September 21, 2004

Mike,

You seem to be concerned about the 24 feet of track. This is not an issue. When distance is a concern it is the distance from the feeder to the end point. So in your case, the distance to each end point is about 3 feet. That's good.

But that isn't the issue in your case. Don's reasoning for placing feeders on each track is because of all the joiners you will have between the feeder and the yard tracks. Also, it is a bad idea to power track through a turnout. Hence the advice to place feeders on each of your yard tracks.

If you think about it, feeders to each track is less soldering than soldering all the joiners together. If you solder the joiners together, that means each rail will have two solder joints to it - one at each end. If you solder a feeder in the middle, you will only hve one solder connection to each rail. That means the opportunity to melt track is cut in half.

When you solder joiners, you affect the track's ability to react to temperature changes. Plus, if you solder all the joiners, if you ever have to do maintenance on the track, you will hate yourself for having soldered the joiners. It will be absolutely miserable trying to make a track repair.

Why should you ever have to do a track repair? Maybe you dropped a tool on the track and bent a rail. It happens.

-- Allan Gartner (wire4dcc_admin@comcast.net), September 23, 2004.

The big problem with DCC is poor connections, not just resistance of the DCC bus or track feeder wires or of the rail itself. It would be a poor choice to power your yard tracks through rail-rail connections at the turnouts. Bite the bullet. Drop a set of track feeders near the middle of each yard track down to connect to the DCC bus. Solder most (but not all) rail joints. Leave a few well placed rail joiners unsoldered so as to allow for some thermal or humidity caused expansion/contraction movement. Drop separate feeders down from each turnout as Allan suggests and you will quickly see that the best place for unsoldered track joiners is at the turnouts.

DonV

-- Don Vollrath (dvollrath@magnetek.com), September 22, 2004.

Thanks for the good advise. However, to confirm my overall understanding, assuming I was to solder all joints, including the turnouts (using Atlas snap switches), would a single feeder at the yard throat be sufficient, in that there would be only 3 feet between the feeder and the furthest place on any of the 8 yard tracks as previously described?

In other words, is the issue one of distance from the feeder to the furthest place away, or is it the collective resistance offered by the 24 feet of track fed by the one feeder?

Thanks,

Mike

-- Mike McGavran (mcgavran@formula.com), September 23, 2004.

Alan, thanks for the quick answer. I appreciate both yours and Don's expert advise and explanation. I described the soldering approach to get "connectivity" out of the equation, so I could clearly understand whether the feeder spacing issue is based on distance or the total "track resistence" involved.

Thanks for clearing this up! And yes, I will be using feeders to the middle of each of my yard tracks!

Regards,

Mike

-- Mike McGavran (mcgavran@formula.com), September 23, 2004.