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Running DC and DCC on the Same Layout?


Lichfeldian
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Further to my earlier post, the layout I am working towards will be run on DCC, but as I don't currently have any DCC locos, I will have to chip all those that are DCC ready. Unfortunately, I also have a number of older locos, some are the dreaded Bachmann split chassis and one or two are old tender drives. I know that even these can be chipped, but with a level of difficulty that is currently beyond my abilities and there is also the issue of cost and the time to do them. I don't want to risk damaging the locos by running them on DCC power, therefore, I was thinking that to start with, I would operate the layout in dual mode, depending on which locos are in use. All the books say not to do this, but why? Surely it should be possible to just switch over the power supply from DC to DCC and back again? I can see there would be a difficulty with DCC wired points, as they would no longer be self isolating in DC mode, but if there is only one loco in operation at a time, or I put in a few isolating sections, what would be the problem?

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I don't see any reason why you can't wire up the layout such that you use EITHER a DC controller or a DCC Command Station with the ENTIRE layout under one form of control*.  Just make sure that you install sufficiently thick wiring to accommodate the current output from the DCC system and include whatever isolating sections you would need for DC operation.

 

However, you DO NOT want a form of cab control where each section can be switched independently to either a DC controller or a DCC controller, since as soon as you run something across a section break that then connects the DC and DCC systems together, you'll likely damage everything: DC controller, DCC command station and no doubt your locomotive decoders.

 

*It is of course possible to have DCC for the track and DC for the accessories or vice versa.  And you could also use different forms of control for entirely unconnected sections of track such as DCC for 00 but use DC for an entirely separate 009 narrow gauge feeder that doesn't intersect the 00 track.

 

Like you, I'm building a DCC layout, but most of my locomotives are still analogue and I intend to use DCC for both the track and accessories (on separate buses) but to also be able to disconnect the DCC track output and connect a DC controller for testing and running unconverted stock.  However, things like DCC circuit breakers like the PSX don't work with DC, so the larger the layout and more complex the DCC layout, the more difficult it will become to make it able to be switched from DC to DCC.  Once you get to block occupancy detection, I think you need to commit to one form of control.

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If you wire your layout as conventional DC with sectioning you would be able to plug in DCC instead as and when, but it REALLY IS A BAD IDEA because sooner or later you will accidentally try running it on the wrong supply, which can do a lot of damage.  As Dungrange has said, yes, you CAN do it, indeed some clubs do so as some members have one system, some the other.  You can even wire it with a change-over switch, but be careful not to knock that switch mid-session!  You have been warned!

 

As for older locos you don't feel up to converting I would suggest you sell them and use the proceeds to replace with DCC.  You won't get as much for them as for current models though.  Some older locos are quite easy to convert, some are difficult because you can't get at the wiring, some smaller locos have nowhere reasonable to put the decoder.  If there a very large number of those , you might want to remain DC on cost grounds.  It might be a worthwhile exercise to analyse your fleet to see how many are in the "too difficult" category, and which you can convert.

 

If you are building a new layout you intend to run it under DCC, it's not worth the bother of providing all the additional section switches and associated wiring for DC.

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It's just too easy to momentarily forget which controller is currently wired in.

 

And very easy to be confused as to which locos are fitted with a decoder and which aren't, especially with a large loco collection, more especially if you have several specimens of a class, and most especially after a lapse of time.

 

 Guess how I know.

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9 minutes ago, Mike Buckner said:

And very easy to be confused as to which locos are fitted with a decoder and which aren't, especially with a large loco collection, more especially if you have several specimens of a class, and most especially after a lapse of time.

 

I'm DCC throughout on my layouts and still have this problem, not being able to remember which locos still need decoders fitting. Simple test is to put it on the track briefly and see if it buzzes!

 

Andi

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The need for care is wise but there is absolutely no reason not to do this if it's what you want. I have a main test/running layout that accommodates anything from 1950s Hornby Dublo to modern Bachmann DCC sound locos. There is no way these can be one or the other, the vintage locos are deliberately original and are not getting hardwired chips. 

 

The layout is set up so that the (few) isolating sections can be switched in for DCC mode - only 'risk' if I forget is that part of the layout is dead. For the main feed, both the DCC and DC controllers are fitted with DIN plug feeds. The DC one is wired for each of the three circuits to be independently controlled. For DCC the three circuits get a common feed. There is only one DIN input socket to connect these to so it is impossible to accidentally switch from one to the other. All the DCC locos will run on DC power, so the only no no would be to go to the trouble of connecting the DCC feed and turning it on whilst there were any DC locos on the layout. I've not yet had this happen....

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