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DCC and DC on same layout

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Posted by alexstan on Thursday, November 22, 2012 6:03 PM
My opinion; don't do it.

Modelling HO Scale with a focus on the West and Midwest USA

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Posted by rrinker on Wednesday, November 21, 2012 9:25 AM

 N scale locos that do not have board replacements are likely to need frame milling. There are still a couple of vendors that offer this service, Aztec is one fo them. Very reasonably priced - they swap your frame with a milled one. http://www.aztectrains.com/dccframes.html which turns the job into a simple wiring operation.

 DO check some of them with the TCS web site. TCS has a new split decoder for many of the Atlas and similar locos that previousl would not take a board repalcement drop in. It's not completely plug and play - the two halves are connected by 3 wires that need to be cut to length and soldered back on, but it's less than a full wire job.

                --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 nittany4 on Wednesday, November 21, 2012 8:28 AM

After reading all of these horror stories and thinking about it more, I have decided to not block the layout and go DCC only...

What I need to find is someone local/Philadelphia/South Jersey that will do decoder installs. I just don't have the time nor expertise (mainly the latter) to do some of these N scale installs beyond a simple light board replacement.

I actually have a decent queue of packaged decoders and their corresponding locos ready and waiting for an install.

Any volunteers?

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Posted by DigitalGriffin on Tuesday, November 20, 2012 2:35 PM

Short Answer:

Is it possible? Yes

Recommended? No

Long Answer:

The NMRA DCC RP specification a packet time out mode in which the train is to brake if a DCC packet is not received in x seconds (specified by a register)  This is implemented by Soundtraxx and QSI and they label them as ways to brake a train.

(One potential scenario: Block switches to red because block ahead is occupied.  This causes a DPDT relay under the table to swich the adjoining block to DC.  The train sees DC signal and this makes it stop automatically.)

This is all great in theory till you get a wheel gap that crosses a DCC - DC boundry.  The current will go the path of least resistence and bypass your decoder completely with all the current draining to ground on the power pack or the DCC booster.  Also some boosters are VERY sensitive to reverse current.  (power pack putting out +15V, and Booster putting out 12V...leading to 3 volts flowing back into booster....this leads to quick burnout for some boosters...ask me how I know.)  One way to reduce this potential is to limit the current on both legs (left and right rail) by putting automotive light bulbs on both legs (thereby limiting current) in the suspect section. 

But either way, it's still not recommended.

On a side note: Lenz came up with a MUCH better solution of assymetric DCC which could be used to signal a brake condition.  But this is not standardized.

Don - Specializing in layout DC->DCC conversions

Modeling C&O transition era and steel industries There's Nothing Like Big Steam!

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Posted by nittany4 on Monday, November 19, 2012 9:08 AM

Thanks, just wanted to be sure there was no special wiring.

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Posted by rrinker on Monday, November 19, 2012 9:02 AM

 I think it's fairly obvious but

DC===<switch>====DCC

                 |

           layout

left two terminals to DC, right two terminals to DCC, center terminals to the layout.

DPDT must be of the centr off variety to be sure it is break before make - so that if you move the switch slowly there's no chance of the DC and DCC sides connecting.

            --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 nittany4 on Monday, November 19, 2012 8:53 AM

Hi,

Is there any chance someone could throw up a wiring diagram for the DPDT switch to chose between ALL DC or ALL DCC?

Thanks

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Posted by brakeman321 on Sunday, February 20, 2011 11:29 AM

According to the Digitrax DCC SuperChief Owner's Manual; pg. 29 section 4.10 : Using DC and DCC together on the same layout:

When running between DCC track sections and adjacent conventional DC powered tracks, both rails must have insulating gaps.

 

The DC supply used must have some form of current control. A 5 - 10 Watt 12 Volt lamp placed in series with one of the DC power pack track leads will work for this purpose.  This allows the DCC booster to drive the locomotive onto the DC track with minimum interruption and stress tot he booster, decoders and locomotive wheels.  When the lamp lights as the locomtive bridges the gaps it acts as a "shock absorber" between the DCC and DC track sections.  It is best to cross these gaps quickly and not bridge th DCC an DC sections for any longer than necessary.

 

Some new Digitrax users belive it is very importatnt to be able to switch between DC and DCC operation as they make the chabes from DC to DCC.  In practice wefind that most of these customers make the change much sooner than originally planed because of the operational benefits of DCC.

 

I am going to run my yards on DC, and the mainlines on DCC with the switch being on the yard lead.

Brakeman321

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Posted by luvadj on Sunday, July 25, 2010 11:55 AM

 I wouldn't suggest you run both together....there's too many chances for something bad to happen even with a dead zone. On my layouts, it's DC or DCC, not both together. I have DPDT center off illuminated rocker switches to show which system is connected.

Bob Berger, C.O.O. N-ovation & Northwestern R.R.        My patio layout....SEE IT HERE

There's no place like ~/ ;)

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Posted by L&NTim11060 on Friday, July 23, 2010 3:53 PM

I have done the same thing,Ive installed a large 3 position automotive switch so I can run my dc and dcc depending on what engines I would like to run....It works well for me.

L&N.....Gone but not forgotten

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Posted by mobilman44 on Friday, July 23, 2010 7:46 AM

Hi!

Welcome to the Forum - a major boon to us RR nuts!

After decades of DC operation, I rebuilt a layout and converted to DCC last year.  To get to the point of your question, my advice is that while you CAN run both DCC and DC on the same layout, it is just a matter of time before something goes wrong and fries some DCC electronics.

As you have a number of DCC locos, I would run them, and work on converting the DC locos as time/money permit.  Start with the easier ones, and go from there.  You will learn a lot, and definitely increase the value and "playability" of those DC locos.

Been there, done that!

Mobilman44

ENJOY  !

 

Mobilman44

 

Living in southeast Texas, formerly modeling the "postwar" Santa Fe and Illinois Central 

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Posted by rrinker on Thursday, July 22, 2010 11:00 AM

jrcBoze

 

Perhaps you cannot quite understand what is being said. The replies are divided between those who KNOW about what will happen, and those still willing to roll the dice.

WHEN (not IF!) you smoke that $300 DCC engine, OR your DCC system, please remember that most knowledgable people have told you NOT TO RUN THEM TOGETHER IN ANY WAY - DPDT toggles are NOT a good protection against your own human error - unless you are perfect.

Our club smoked a number of DCC engines. I watched one literally smoke up one end of the layout. I too wanted to do dual operation with toggles and isolation tracks. I made one mistake, I will never never do that again.

Good luck fellow retiree.

jrc

 Think you missed what I said. ONE toggle, either the entire layout is DC or the entire layout is DCC. NO CHANCE of connecting the systems. I do NOT think the idea of running both with one cab wired to the DCC system and one cab wired to a DC power pack is a good idea. One 'empty' block between trains or not - one little slip up and POOF. It doesn't even have to be a powered loco that crosses the boundary - metal wheels will bridge an insulated gap just fine.

 Bottom line - there is ONE way to have a layout that has capability for both and is completely safe - want uyltra-safe, use an old-style knife DPDT switch. Absolutely impossible to connect the inputs together unless you drop a pair of screwdrivers onto the switch at just the right place. The individual block method is just askign for trouble, especially if more than one person is running trains, or when you are distracted showing off your awesome new model railroad to visitors. One leg on my benchwork has 2 holes in it - I drilled the hole while talking to a visitor and managed to get it too close to the corner so I couldn't get a wrench in to tighten the bolt. Easy fix but it's easy to get distracted when showing off your creation, too.

 Also, the whole other issue is that once you start playing with DCC you'll not WANT to go back. A short piece of track connected tot he old DC power pack is sufficnet to test a new loco on DC before installing the decoder.

                                        --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 jeffrey-wimberly on Thursday, July 22, 2010 9:14 AM

 If you're going to run them at the same time at least have a section of dead track between them that's no shorter than your longest consist.

Running Bear, Sundown, Louisiana
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Posted by jrcBoze on Thursday, July 22, 2010 8:06 AM

 

Perhaps you cannot quite understand what is being said. The replies are divided between those who KNOW about what will happen, and those still willing to roll the dice.

WHEN (not IF!) you smoke that $300 DCC engine, OR your DCC system, please remember that most knowledgable people have told you NOT TO RUN THEM TOGETHER IN ANY WAY - DPDT toggles are NOT a good protection against your own human error - unless you are perfect.

Our club smoked a number of DCC engines. I watched one literally smoke up one end of the layout. I too wanted to do dual operation with toggles and isolation tracks. I made one mistake, I will never never do that again.

Good luck fellow retiree.

jrc

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Posted by jdobo on Thursday, July 22, 2010 3:30 AM
rrinker

 The ONLY acceptable way to do this is have a big DPDT toggle switch. Once side goes to the DC system, the other side to the DCC system, and the middle to the layout. Using a CENTER OFF switch so there is no chance of connecting the systems. Then the layout is EITHER DC or DCC, NEVER both at the same time.

                              --Randy

This is what I do so that I can still run some of my older equipment, It works well . Regards Jon.
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Posted by jeffrey-wimberly on Wednesday, July 21, 2010 9:06 AM

Bedbug
I recently retired and am getting back into n scale after a hiatus of several years. I have a small (4x10) layout with 11 blocks and 12 turnouts that is wired for duel cab DC operation. I have acquired several DCC locomotives to go with a rather large collection of DC locos. In order to operate both types of motive power, I would like to convert one of my duel DC cabs to DCC. On the surface that would seem lime a pretty simple thing to do. Has anyone else done that and can you offer any tips or advice?

My layout (16 blocks) is set up to do exactly what you're proposing. Each block is on it's own DPDT switch that can switch between DC and DCC. I almost always run DCC now and hardly ever use the DC anymore. Sometimes I may use a pair DC switchers on the passing track to move cars around but for the most part I use the DC to test DC locos to see if they run well enough to take the time to install decoders in them. Only once has a DC loco bridged the gap between DC and DCC. That resulted in my Digitrax system tripping and shutting down. And soon as the loco was removed the system came back up.

Running Bear, Sundown, Louisiana
          Joined June, 2004

Dr. Frankendiesel aka Scott Running Bear
Space Mouse for president!
15 year veteran fire fighter
Collector of Apple //e's
Running Bear Enterprises
History Channel Club life member.
beatus homo qui invenit sapientiam


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Posted by SpaceMouse on Wednesday, July 21, 2010 8:52 AM

My ex-club did what you are talking about. The spent hours rigging the DCC and DC so they could work together. As soon as they started running DCC, no one ever wanted to run DC. This was several years ago and they still talk about all the time and effort they wasted. 

I'm not saying this is you, but most of the people who talk about all the locos they have to convert, usually have 10 or 15 runners and 85-90 shelf queens. In reality, you only need to upgrade the runners. If you get a Zephyr or ProCAB you can run the shelf queens on 00 every once in a while as the whim strikes, without converting them.  

Chip

Building the Rock Ridge Railroad with the slowest construction crew west of the Pecos.

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Posted by pastorbob on Wednesday, July 21, 2010 8:45 AM

Having used DC, then command control (non DCC), and now DCC for the last 11 years, I strongly suggest you NOT do what you propose.  Several have given you workaround solutions, but unless you are a recent immigrant from Mars, you WILL slip some day and get the two tangled.  I have known and seen that happen on several different layouts.

I was forunate with my conversion as I had been using Dynatrol and I just had to replace Dynatrol components with NCE, no wiring changes and I was good to go.  At that time, Dynatrol was winding down but had a receiver/decoder, made by NCE that would recognize either signal, so I started a year in advance putting in the decoder/receiver so I would have several engines converted before DCC day.  When it came, all went very well.  In fact, I still have a few diesels with that original decoder/receiver still working.

But bottom line, I get around to several different layouts during the year, and know of three who tried to run DC and DCC with switches, and relays and witches curses, and they still ended up frying a decoder. Do as you wish, but you were warned.  The Martians are gathering right now at your house.

Bob

Bob Miller http://www.atsfmodelrailroads.com/
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Posted by rrinker on Wednesday, July 21, 2010 6:27 AM

 The ONLY acceptable way to do this is have a big DPDT toggle switch. Once side goes to the DC system, the other side to the DCC system, and the middle to the layout. Using a CENTER OFF switch so there is no chance of connecting the systems. Then the layout is EITHER DC or DCC, NEVER both at the same time.

                              --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 MisterBeasley on Tuesday, July 20, 2010 10:59 PM

davidmbedard
Dont do it.  If anything spans the gap between the 2 systems, your DCC system will die.

 

Read that.  Now read it again:

davidmbedard
Dont do it.  If anything spans the gap between the 2 systems, your DCC system will die.

 

Please, don't try to run them both together.  It's a recipe for disaster.  The Titanic Railway.  The Hindenburg Central.

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

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Posted by Texas Zepher on Tuesday, July 20, 2010 9:47 PM

Bedbug
... is wired for duel cab DC operation. ... I would like to convert one of my duel DC cabs to DCC. On the surface that would seem lime a pretty simple thing to do. Has anyone else done that and can you offer any tips or advice?

Yes, I ran that way for several years.  I had multiple incompatible command systems.  I had 4 cabs that were originally all DC.  When I went to CTC-16 I replaced cab 4 with that system input and continued to run DC on the other three.   When I wanted to run the CTC-16 I just flipped all the block selectors to cab 4.  Ta-Da command control layout!   Later I added CVP rail-command and switched cab 3 to be that.  Then as time went on I replaced the old CTC-16 on cab 4 with DCC.   After a while I seldom ran the two remaining DC cabs the command control systems were just so much easier and funner to run.  Eventually, the only time I used cab 1 was for the good sound units (PFM sound).

That layout is gone.  Now the only time I get to use the PFM sound is when I hook up a special arrangement for it - mostly just the Christmas tree trains.

My advice - run the layout as DC or DCC never have them both powered up at the same time.  That is have all the cabs set to block 1 for DC or have all the cabs set to block 2 for DCC.  Don't try to run them both simultaneously with one DC loco on one cab and a DCC locomotive with the other.  Many strange and bad things can happen.   In fact it might not be a bad idea to put a DPST cut out switch on the unit.  Or a DPDT switch to change the cab from DCC to DC  that way in addition to being certain the DCC was not engaged you could still have two DC cabs and operate as normal .

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Posted by richg1998 on Tuesday, July 20, 2010 7:36 PM

 If you are not paying attention, a DC loco can cross into the DCC section that may be powered by the DCC controller.. That happened at our club and burned out the NCE 5 amp Power Pro. We no longer power DC locos on our club layout that was wired for fourteen blocks. We thought we could keep Murphy out.

It can be done but you better know what you are doing.

This has happened to a couple others I have seen in forums.

Don't forget Murphy.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

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Posted by Bedbug on Tuesday, July 20, 2010 7:02 PM
When I built the layout, I isolated both rails on all blocks with plastic rail joiners and separate feed lines.. The layout also has 2 reverse loops. Are they an issue?
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Posted by Hamltnblue on Tuesday, July 20, 2010 6:53 PM

You can run both the same time if you totally isolate sections. You can also switch between DC and DCC with a switch if you want to run either/or.  I suggest the later and convert the dc loco's to DCC over time.

Springfield PA

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DCC and DC on same layout
Posted by Bedbug on Tuesday, July 20, 2010 6:50 PM
I recently retired and am getting back into n scale after a hiatus of several years. I have a small (4x10) layout with 11 blocks and 12 turnouts that is wired for duel cab DC operation. I have acquired several DCC locomotives to go with a rather large collection of DC locos. In order to operate both types of motive power, I would like to convert one of my duel DC cabs to DCC. On the surface that would seem lime a pretty simple thing to do. Has anyone else done that and can you offer any tips or advice?
Tags: DCC

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