Wiring A Block Section For DCC

[BR60103]

If you have all rail frogs (electrfrog) in your turnouts, you need an insulated joint beyond the frog somewhere. (Same for DC and DCC). The dead end of a siding counts as an insulated joint. You need a set of feeders for the track beyond the insulated joint. You can use the turnout to "kill" a siding by setting it the other way; this is frequently handy.

[jfugate]

Turnouts can be a problem especially if you use powered frogs rather than dead frogs.

Where the rails cross on a turnout is called the frog and to avoid shorts there you either need to gap the turnout at the frog to create a short piece of dead track, or you need to change the polarity of the frog based on the position of the points.

If you use a powered frog, it is possible to run a locomotive into a turnout from the frog end with the points thrown against it. If you do that you will get a short once the loco reaches the frog because the frog will be the wrong polarity with the points thrown against you.

Getting a short on a DCC layout can be a problem because it will shut down the power booster, which can shut down the entire power district fed by that booster. If you have a small railroad with only one DCC power booster, then the short to the booster can shut down the entire layout.

It is possible to use dead frogs and most modern all-wheel powered locomotives will roll right through the dead frog, getting its power from other parts of the turnout on the rest of the wheels that pickup from the track.

Or with a powered frog, you can add an 1156 automotive tail light bulb in the feeder going to the frog. This will cause the bulb to light if you run into the turnout with the points against you and will simply be seen as an increased load to the booster rather than a short. This means the booster will not shut down the entire power section, but will allow things to keep running.

It's also possible (but unlikely if wheels and track are guaged right) to get a short at the points end if the closure rails are all one polarity in a powered frog arrangement. The so-called "DCC friendly" turnouts have the closure rails and points be the same polarity as the adjoining stock rails to avoid this problem.

But if things are guaged right, this isn't ever much of a problem ... it's the frog end of the turnout that you need to deal with to avoid most shorts, I've found.

[Anonymous]

You are combining the ideas behind both DC and DCC (as I understand it). The answer to your last question is that you cannot avoid running into each other with DCC. It is actually possible to crash because with DCC you are controlling the train, not the track. The track is always on at "full" power. The DCC controller sends a message through the rails to the decoder, and the decoder tells the engine what speed and direction.

For more on the concepts and terminology in DCC, I would direct you to a site set up by the guy that helped set up our club's Digitrx DCC: http://www.railwaybob.com/Modules/MRIndex.htm . There are plenty of other resources you can find here (trains.com) and elsewhere on the internet.

Andrew

[Anonymous]

Thank You Andy and Andrew for your replies.
But NOW I'M Totally confused.I understand that you need to wire a reverse section and a turntable with blocks but what about turnouts. Do they need to be insulated as well?Also, I understand that blocks are used to let you run more then one train at a time.With out blocks how can you avoid one train running into another. Am I on the right track or totally off center here. Please help.
Thank you all in advance.

Louie

[Sperandeo]

Hi Louie,

With DCC you don't need blocks unless you want to have a working signal system. If you already have an isolated section, just give it its own set of feeders connected to the same bus as your other tracks, and it will be as if the gaps or insulated joiners weren't there.

You do still need to insulate turning tracks, such as reverse loops, reversing cutoffs, the tail tracks of wyes, and turntables. You may elect to continue to control these with auxilliary reversing switches, and especially in the case of loops and wyes where you can use auxilliary switch motor contacts this is often the simplest solution. For other cases, and where you don't have switch motor contacts to use, several DCC suppliers sell automatic reversing modules to control turning tracks.

Good luck,

Andy

[Anonymous]

If you are already "blocked", you can run your DCC by selecting all the blocks to be run by the DCC unit in place of Cab 'A' (or whatever you call it). While I am still learning about the specifics of DCC from the club, the only special consideration seems to be a reversing loop.

In term of feeders - if you have block control, you should already have a feeder in every block, especially if both rails are gapped. DCC relies on the rails to get the signal to the decoder in the loco, so more feeders (as frequent as every three to six feet) are recommended.

There are some real DCC experts here though who may be able to offer more help.

Andrew

[Anonymous]

Hello,

Thank You everyone for all your help with my last post. I now have another question. When doing a block section( both rails insulated on both sides) do you still have to place a feeder wire within the block section when using DCC.
Someone told me that you still need to use a DPDT Toggle switch with DCC. Is this correct or is there a module that lets you control it or can it be done thru your handheld controller?What is the best way to control a block section with DCC.
Thank You all again for your time with this question.

Louie