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Centralized vs Distributed Electronics

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  • Member since
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  • From: Richmond, VA
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Centralized vs Distributed Electronics
Posted by carl425 on Thursday, January 15, 2015 8:28 AM

 

I've got about a dozen circuit boards (RR-CirKits) that I'm using for block detectors and switch machine drivers.  I'm having a hard time deciding whether to centralize them in one location or distribute them around the layout.  Most of the pictures folks have posted of their wiring show everything mounted on a single board with a large bundle of wires leading away.  I don't see many, if any, examples of distributed installations.

 

I'm interested in opinions.  Have you done it one way or the other and would do it differently if you started over?

 

I have the right to remain silent.  By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.

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Posted by MisterBeasley on Thursday, January 15, 2015 9:51 AM

I look at things like this from an engineering standpoint, in particular the length of wire runs.  If you are driving switch machines and picking up detection signals, you are probably better off locating the electronics close to the sources and destinations of the wires.  I have a couple of auto-reversing units, and I have mounted them near the loops they control.  Likewise, my stationary decoders are close to the groups of turnouts they control.

There are good reasons for this.  First, you lose power over long wires, so that circuit that runs your turnouts just fine on the bench may not do so from 30 feet away.  Next, it's easier to maintain, with shorter distributed wire hubs instead of thick bundles of cable.  Finally, wire has gotten very expensive over the last few years.  Keep your runs short and save money.

It takes an iron man to play with a toy iron horse. 

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Posted by cmrproducts on Thursday, January 15, 2015 9:53 AM

While I don't have any Switch Decoders or Block Detection -

I do have a number of PM42 Circuit Breakers as well as Boosters to go along with them.

I have them located close to the blocks they control - trying to keep the BUS lines as short as possible - but this doesn't always work out.

Reason is I tend to make changes to the block sizes as I keep adding/replacing my engine fleet with newer Sound Engines.

This then makes the need for smaller lenght blocks (to keep the max number of Sound Engines that can gather in any one block).

So now my BUS lengths are shorter because of the smaller lenght block but need to run back to the Booster/PM42 Circuit Breakers (due to there being 4 to a circuit card).

Same goes for the Auto Reversers - they almost have to be located right at the insulator point to get them to work realibly.

So YES I do have my components located as close as possible to the areas they serve.

BOB H - Clarion, PA

 

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Posted by Stevert on Thursday, January 15, 2015 9:53 AM

Carl,

  I use a combination of both methods, and if I started over I'd probably do it similarly to what I have now.

In one location, I have my command station and it's power supply, a PM42 and it's power supply, a DS64, an AR1, and a couple other power supplies (one for the DS64's and one for the UP5's).

Then located at various points around the layout I have nine more DS64's and another AR1.

For the remote DS64's, it makes sense to run only the LocoNet cable and 12 VDC power cable (zip cord, actually) out to the far ends of the layout, rather than running two wires from a central location to each switch machine at the far ends of the layout.

For the "remote" AR1 it probably doesn't matter much, but I followed the same general principal as with the DS64's by putting it near where it's needed and extending the "supply" side rather than the "load" side.

I'm sure you'll get other replies with other preferences and/or rationals; my suggestion would be to consider them all and decide what makes the most sense to you for your specific circumstances.

But no matter how you do it, as you put it all in place, DOCUMENT, DOCUMENT, DOCUMENT!   

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Posted by gandydancer19 on Thursday, January 15, 2015 10:03 AM

I also use both methods.

My DCC system and main circuit breakers for the power districts are in a central location.  I have also installed a detection and signal system that uses three sets of Digitrax BDL-168's and SE8C's.  These board pairs are located together, but the three sets are located in the middle of the layout sections they control, for ease of wiring.

So it really depends on the type of electronic items that you are using.

Elmer.

The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.

(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.

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Posted by carl425 on Thursday, January 15, 2015 11:09 AM

Thanks for the responses.

My initial thought was to distribute - pretty much for the reasons mentioned above.  Then in trying to figure out how to do it, I ended up needing to over configure the boards at the different locations.  My plan was to find one location on each wall to do a "distributed consolidation" but any remotely logical determination of what device should be connected at which point required me to use several more total boards than a consolidated strategy would require.

There's always something that forces me to stop building and start procrastinating.  Maybe I should just bite the bullet and buy a few extra boards.

I have the right to remain silent.  By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.

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Posted by Stevert on Thursday, January 15, 2015 11:54 AM

Yeah, you're over-analyzing it. 

A couple of my "distributed" DS64's have an unused output or two.  In one case, I added another spur nearby so it came in handy. 

For the other, I'll think of something.  And if I don't, oh well.   

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Posted by Phoebe Vet on Thursday, January 15, 2015 12:37 PM

Mine looks like the boards you mentioned but the fact is I have 5 of these boards scattered around the layout.  So it depends on how far you have to run your wires.

 

Dave

Lackawanna Route of the Phoebe Snow

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Posted by rrinker on Thursday, January 15, 2015 2:41 PM

 See, with something like the BDL-168, you don;t have much choice other than to 'centralize' them, at least to some level. Well, you could add the remote sensing diodes to them and do that..

 With the RR-CirKits block detectors using transformers, you can take a more distributed apprach. Each trnasformer cna go near the block sub-bus it is detectiong - the signal can be fed back using ordinary twisted pair wires, like Cat 5 networking cable. This is cheaper and easier than running heavy bus wires everywhere, also keeps the bus runs shorter for less voltage drop.

 Each board runs 8 detection zones, those connect back to the Tower Control with 10 conductor ribbon cable, or the boards can plug directly in. Ribbon cable isn;t nearly as noise blocking as twisted pair, so you need to be careful how it gets routeded, an dhow long a run you make. So you cna have a few of the BOD-8 boards fanned out from the Tower Controller via the 10 pin ribbons, just not huge distances. The you have each BOD-8 board, with two sets (4 pair per cable) of twisted pair cables going out to the actual detection locations. Check on the recommendations in the instructions, or email Dick, he's very responsive, if you are not sure. Better to get them connected properly than to have all sorts of false and/or missed detections and try to troubleshoot it after everything is in place.

 Now for the main power - I am definitely a fan of distrbuted. Say you get lucky and have a 50x100 building for a layout. Even if you are only going to run by yourself, you will need extra boosters. Let's keep it simple - 50x100 around the walls, nothing int he middle but wide open space. Total 300 feet all around. If you put just one booster in, and run bus wires around in each direction, each bus run will be 150 feet - 300 feet of wire on each bus, for the complete circuit. Even with a simple doubleheader being the only train running, even #12 wire will have noticable voltage drop out near the ends of each bus run, with 300 feet of wire to go through. #10 wire probbaly would as well. Got some surplus spools of #4? That would probbaly work fine. But would that be a pain to work with, you'd need a torch to solder to it, and I don't think 3M has a suitcase connector to tap off a #4 main line. Plu sif you had to buy 600 feet of #4 wire...  Instead, buy some extra boosters, Locate them 50 feet apart, so no bus run needs to exceed 25 feet (50 feet of wire). Even #14 wire will work here, and since the control bus from command station to booster isn't subject to much current, even though it is telephone wire in size, there is almost no voltage drop - which promptly gets amplified by each booster back to the proper voltage tot he rails anyway.

              --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by carl425 on Thursday, January 15, 2015 4:25 PM

rrinker
Each board runs 8 detection zones, those connect back to the Tower Control

I'm using the Motorman and Watchman boards instead of the Tower Controller.  These boards have 8-ports on the board and a connection for the same 8-port cards that go in the Tower Controller.  They are all connected by a 3-wire LocoNet Compatible Simple Serial Bus.

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Posted by rrinker on Thursday, January 15, 2015 5:05 PM

 Well, those boards are definitely designed for distributed installation. Wish I could get to Springfield this year and talk with Dick Bronson again. I'm not sure the benefit, at least for the example given of a passing siding, where all those seperate boards would be better than the Loconet Control Point, which has the inputs for enough block detectors and outputs for enough single heads and switch motors. In my case, it might make sense to go with the individual boards, because I would not be using the Switchman board, I use servos for switch motors, not Tortoises or twin coil motors.

                  --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by BroadwayLion on Friday, January 16, 2015 7:11 AM

Centeralized:

Decentralized:

Two sides of the same coin if you ask me!

 

ROAR

The Route of the Broadway Lion The Largest Subway Layout in North Dakota.

Here there be cats.                                LIONS with CAMERAS

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