How many separate section are really needed for DCC?

[Epimetheus]

I'm getting the track prepared for DCC and need a little clarification. There is some balance between one continuous track and dividing it into many blocks to manage short circuits. Any help is appreciated.

This is a moderate sized HO layout, 13x13 ft with two complex switching puzzles and no more than 4 locos actually moving at any given time. No reversing loops or wyes. Right now the track is pinned in place after the try-and-fit-it stage. Before I fasten it down, I could use insulated rail joiners everywhere or leave whole patches continuous.

Yeah, I know, DCC does not require block control. Then about the 3rd page of any DCC primer shows the track electrically isolated in many places to manage short circuits. "But that's not a block", you say, "It's a Power District!". OK, I agree. I still gotta cut the track and run two jumpers and a DPDT switch into the non-block.

The programming track I understand the isolation. Does it make sense to put that on a separate board, the test track?

Thanks muchly,
Doug

 

[goscrewyourselves]

Doug,

There is a lot in your question/s? Kind of 3 or 4 questions in one, I think.

1. It is DCC and therefore NO blocks are required as you said.
2. You only NEED insulation joiners relative to the Turnouts
3. On a layout of that size, depending on the system you are using, you may only NEED 4 sets of feeders located N/S/E/W
4. It is highly recommended to have feeders every 3' - basically, one set of feeders per flex track section
5. Yep, it makes sense to have a separate board for your piece of programming track.

 

[dinwitty]

basic track smarts still are in play, having good feeders in the right places, don't rely on joiners to send power, insulate turnouts where needed. Most systems can handle 4-5 engines at once, this is more current however than your old DC pak. Certain areas of your layout you might want power isolation, places like turntables, loco storage, where you feel you really need to cut power. Larger layouts may need extra boosters around the layout, this creates super blocks. The differrence here is if you use signals your going to block out your track anyway to handle signals so thats a whole differrent animal. Blocking like this gets you back to the DC style bloacking but whoopee, its going to happen, all depends how you handle your layout. cheers.

 

[trailrider]

And you run 4 trains at a time? How do you stay sane? My layout is in a 14 x 14 room, and even with DCC, I have trouble keeping track of more than one train at a time! That and chew gum! The main thing you need to do is be sure all turnouts are fed from the point end, and if two or more turnouts have the frog ends facing each other, you do need at least one set of insulated joiners between them.

 

[goscrewyourselves]

"...The main thing you need to do is be sure all turnouts are fed from the point end, and if two or more turnouts have the frog ends facing each other, you do need at least one set of insulated joiners between them...."

No offence to anyone BUT that is the simplest and one of the clearest explanations regarding turnouts and insulated joiners I have read!

 

[Iron Horseman]

There is some balance between one continuous track and dividing it into many blocks to manage short circuits.

This is a moderate sized HO layout, 13x13 ft with two complex switching puzzles and no more than 4 locos actually moving at any given time.

I assume that is one loco in each switching area, and two in other places (the main line). Is there a loco storage facility? I think I would make each switching area a district, and probably one for the rest. Maybe one for the loco area if there is one. Any more than that and it is getting into unnecessary complexity.

 

[tootnkumin]

A power district is different to having feeders to a bus wire around the whole layout. The name suggests it. It, or they, are separate sections of the layout, insulated from each other and with their own power supply/ies. If your layout only has or needs 1 supply, then it is 1 power district and it will have it's own short circuit/shut down function. The purpose of multiple power districts is so, if a short/shut down occurs in 1 district, none of the others are affected. I.E. trains will keep running in those other districts. The benefit of DCC is that trains can run from 1 district to the next and so on without needing to stop or lose control from the cab/s operating it/them. The only proviso would be, with a tethered cab that is connected into the shorted/shut down district, there'd probably be (haven't checked) a loss of control if your train was in an active district. A quick sprint to reconnect would be likely.

 

[trailrider]

No offence to anyone BUT that is the simplest and one of the clearest explanations regarding turnouts and insulated joiners I have read![/COLOR]

Thank you!
I should have added, that if two turnouts face each other, say at a crossover...where the two diverging tracks face each other, BOTH tracks need insulated joiners or at least gaps in both rails. Polarities will have to be matched. This is true of DC and DCC.

 

[gator do 65]

Trailrider,
Could you please give us a diagram or two? I'm just not getting it!

 

[trailrider]

I don't have the means to post it, but think of it this way: You have two concentric loops of track, with two turnouts facing each other, allowing a train to cross over from one loop to the other. Both rails that connect the two turnouts need to have insulated joiners between them. Same thing is true if you have a single loop with two turnouts that have the frogs facing each other. Both rails need to be insulated. In that case, you need to separate the single loop of track into separate blocks or power districts, and have a DPDT electrical switch or a polarity reversal module to match the polarities of the two districts. I run both DC and DCC, and match the polarities with the DPDT when crossing from one side of the loop to the other (basically a reversing loop). Maybe somebody else can post a diagram.

 

[Iron Horseman]

I don't have the means to post it, but think of it this way: You have two concentric loops of track, with two turnouts facing each other, allowing a train to cross over from one loop to the other. Both rails that connect the two turnouts need to have insulated joiners between them.

This is just not true unless one has accidentally wired the two concentric loop the opposite of one another. I believe this reply is confusing the insulated joiners and wiring requirements for hot frog turnouts with the wiring of the track in general. These are two separate issues. Concentric loops do not require any special wiring regardless of how many crossovers there are. It is the design of the turnouts that determines if insulated joiners are needed or not. Insulated frog turnouts do not require any. Hot frog turnouts require insulated joiners.

Same thing is true if you have a single loop with two turnouts that have the frogs facing each other. Both rails need to be insulated In that case, you need to separate the single loop of track into separate blocks or power districts, and have a DPDT electrical switch or a polarity reversal module to match the polarities of the two districts. I run both DC and DCC, and match the polarities with the DPDT when crossing from one side of the loop to the other (basically a reversing loop). Maybe somebody else can post a diagram.

The key words in this paragraph are "crossing from one side of the loop to the other [side]", because that does create a reversing loop.

One does not need separate power districts just because there are two concentric loops with crossovers.

I interpret the OP's question to be that he understands how to wire it just fine. The question is where to break it up for power districts for effective operation not short circuit prevention.

 

[tootnkumin]

Epimetheus's original post contained these statements and questions.

How many Power districts needed for his layout size
Managing short circuits
2 complex switching yards
No more than 4 locos moving at one time
No reversing loops or Wyes.
Any need for a separate test track as well as program track

Number of power districts = 4 locos and the size of layout should work fine with a 5amp system and you should be able to have quite a few more sitting idling i.e. powered up. The proviso is, for short circuit/shutdown, a few districts would be good.

Separate power districts for your Switching yards would be good, because this is where you'll most likely have any derailments, so to extrapolate, 3 power districts as a minimum in that circumstance would be required (the intermediate 2 could be supplied with power from 1 power pack), 4 if you want to power all districts separately.

Need for a separate testing track? Only if you want one separated from the layout, but of course it too will have to receive power (and control) from somewhere.

 

[Epimetheus]

It's starting to make sense.

Separate power districts for your Switching yards would be good, because this is where you'll most likely have any derailments, so to extrapolate, 3 power districts as a minimum in that circumstance would be required (the intermediate 2 could be supplied with power from 1 power pack), 4 if you want to power all districts separately.

I was cogitating on it for a while last night and that confirms some of my thoughts. Good to know this novice is not entirely off. I was imagining each switching puzzle should have its own district exactly because more turnouts means more chance of derailments and shorts. The single-track main is interrupted by the switching areas, creating two more power districts. Any more divisions are optional. It can get fancier after installing a turntable - much later.

One puzzle has set-out spurs along the edge of the layout. I will isolate those just to park engines without power. Maybe use one as a programming track. Alternately, I do not have a problem adding a socket to a separate programming board for extra protection against disastrous shorts.

Four trains at once would be confusing. I meant four motive units, perhaps a double-header on the main, an active switcher, and one powered up waiting in the wings. That is two trains on the move, definitely enough for one operator and a single-track main. It is a small space. More than two operators means they better be really good friends.

Time to glue down some track!