Multiple DCC areas?

Discussion in 'DCC & Electronics' started by Travellar, May 7, 2007.

  1. baldwinjl

    baldwinjl Member

    I think you missed simplest, and best (other than just using one system). No need for relays and automating, just a switch. I still don't like the inductor idea, at all. I think you've gone off base there, though it may work. DCC is more like DC than AC, the voltage changes quickly, then stays put for a while. Just make a bridge with three sections of track.
    Section one: System one/Dead
    Section Two: System one/System two
    Section three: Dead/System Two
    Drive onto the bridge, throw the switch, drive off the bridge. If you want to sense and automate, you can, but you are still going to have to have a throttle ready to control, so why not leave it manual anyway. I wouldn't introdure DC into the mix at all. It only adds unessessary confusion, to me.

  2. BigJim

    BigJim Member

    I certainly don't understand the inductor idea. DCC can have long DC output pulses. I think they are on the order of 83 milliseconds. Yes, the normal pulses are 8 khz & 16 khz but the allowed long pulses are in the 12 hz range. This is a VERY LARGE inductor to be a couple of ohms at DC and 100+ ohms at 12 hz.

    You will need at least one very long isolation track. Consider layout 1 & 2, isolation track A. Match 1 & A. Drive train on to A. Track has to be as long as the entire train since any metal wheel, pick-up or not, will short the gap when 1 <> A. Now switch so A matches 2. Drive train on to track 2. You cannot drive ANY metal wheel across a gap that has different power sources on either side. I guess you could have plastic wheels on all of your rolling stock but after changing my passenger cars from plastic to metal wheels and seeing the difference in rolling through turnouts I will never go back to plastic. My 8 car passenger train is almost 9 feet long. With a little slop for starting and stopping I would need a 10 foot isolation track.

    You might be able to use small dead sections at either end of the isolation track to avoid the single wheel shorts but, since the "dead" track has to be shorter than the loco pick-up length (or it will just stop) any error in sensing or switching would still cause a short DCC to DC.

    It is my understanding that some of the smaller DCC units can be used in slave mode as a booster networked to a host unit. So the easiest AND best method would be to have section 2 with a smaller unit. Slave it to the main host unit for connected operation. Disconnect it from the host for stand-alond operation of section 2. Use RF, IR or multiple plug-in spots for walk-around DCC controllers. Lose the DC idea. I know it was marketing hype but "drive the trains - not the track".

    Might be a little more expensive to start (not counting the 50 pound inductor or sensors & relays) but much cheaper than burning out a DCC unit with DC voltage on the output when somebody rolls a metal wheel boxcar across one of the gaps or a DCC loco that didn't like switching to DC while operating in DCC mode.

    There are some VERY LARGE, multiple room club layouts and modular layouts that all run on a single DCC system with boosters and walk-around controls. These are run by smart and experienced MRers. If your "Best" was was best I think they would use it.
  3. pgandw

    pgandw Active Member


    Every poster has agreed that a single DCC command station setup with multiple throttles at multiple locations is the cleanest; simplest to install, operate, and maintain; and likely the cheapest overall solution. Throttles can be tethered handheld or wireless handheld, and a few can be fixed. If more power or flexibility is needed, multiple power districts are set up. This is how club layouts and modular setups implement DCC.

    Yet you want to go a different path. That is certainly your choice. But if you have already decided on a different path, then just tell us so. We're not going to police how you do things; we'd just like to know how it works out in the end.

    my thoughts, your choices
  4. Travellar

    Travellar Member

    My original suggestion pretty much went out the window as unneccisary somewhere around the bottom of page one. :lol: From there, it's been mostly a matter of trying to solve an (unneccisary) engineering problem.

    Big Jim: I wouldn't think I'd need a dead track more than perhaps a quarter of an inch long to avoid metal wheels being a problem, although I didn't realise that some DCC pulses are on the order of 83mSec.

    And as one final coffin nail in the original concept, (my idea, I get to bury it!), While the DCC controller for my set up right now would have difficulty linking together with other controllers, I've missed the point that the multi-layout setup I suggest would require the aquisition of more controllers anyhow. So one really good controller, with support for multiple walk around modules would handle everything that my multi controller scheme could, and admittedly, do a better job of it.

    Incidently, the relay switching suggestion wasn't one for DCC-DC-DCC, it was simply a switchover for DCC-DCC Again, it's become a purely academic excercise anyhow.
  5. baldwinjl

    baldwinjl Member

    Just 'cause this is so much fun, I was thinking system1 to system 2 where either system could be DC or DCC. The tracks on either end are just to ensure that you can't possibly overrun and short the systems together, no matter how hard you try. Well, there might be ways, but you'd need to be creative!

  6. BigJim

    BigJim Member

    Don't throw away the old, smaller controller. With a switch/relay you could connect one of the separate parts of the layout to the main system or the small controller. I would kill the connecting track at the same time.

    Might be useful if the kids wanted to play on the separate section and you wanted to make sure they didn't mess with the stuff on the main layout.
  7. pgandw

    pgandw Active Member

    Or use the smaller controller at the workbench and/or test track - especially if it can read/write CVs and/or supports a programming track.

    just my thoughts
  8. MadHatter

    MadHatter Charging at full tilt.

    I remember reading in my Digitrax manual that one can install a section of DC current, but not for the reason you want to use it- they suggested using it to maybe let your loco slow down and stop before a signal or something.

    I would go with the power districts idea.

    1) Much less work involved.
    2) If there is a short in one of the yards, only that one yard would be affected thus making fault finding easier.

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