1. ScaleCraft

    ScaleCraft TrainBoard Member

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    Hey. All those years in boats we never saw a horizon, so it must be, right?

    I use what works with minimal futzing around.

    Conventional track power or straight battery r/c (none of that dcc carp jammed into it).
    1911, and not an A-1.
    Flathead Fords.
    Vacuum tube radios.
    Even have dial phones in a drawer.
    XP Pro.


    Scotty said it very well...the more complicated you make the plumbing, the easier it is to stuff up the drain...or something to that effect.
     
  2. Doug Gosha

    Doug Gosha TrainBoard Member

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    Insult aside, you ignore the most important aspect, resistance, in favor of a secondary concern.

    Doug
     
  3. DCESharkman

    DCESharkman TrainBoard Member

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    I am looking at this as an impedance, because material properties vary and change with frequency. It has a real part called resistance, and a complex part called reactance. In DC, reactance is zero. So it is only about the resistance.

    DCC is a complex modulated high frequency pulse with a repetition of 8KHz. This means none of the rules for DC apply any longer. In fact the AWG no longer applies because it is only valid for DC and 60Hz AC power. So transmission line theory is more accurate than AWG for DCC. The true frequency content is not the 8KHz pulse repetition but the modulation inside the pulses which is considerable higher. Also add in the fact the edges are all squared off and not smooth and slowly changing like a Sine wave means it takes even higher frequencies to generate the squared edges. This is all explained in many signal theory texts and is factual science.

    When you look at from the signal theory aspect, more material means more reactance. More reactance means more signal degradation because more of the power is being held in the reactance. This is what causes the ringing on the leading and trailing edges of the pulses. It is because of the reactance that the resistance can be less in smaller wire than larger wire because the combination of reactance and resistance are also dependent of the material properties of the wire. If it is solid, then it can be even more dependent on the material properties. If it is stranded wire, the properties involve the number of strands, the gauge of the strands, the twist rate of strands and also the material properties of the strands. While the effects may be minimal, they are still there. And since track and wire drops are added to the mix, they have their own effects. In some case they can correct or minimize the reactance of the bus wire, and in some cases they can increase it. So it is always better to have as clean a bus wire to start with.

    Smaller wire is dependent on current still, but not as small as motor winding wire, a remark I found insulting. In reality you can get just as good DCC bus wire performance with a good 16 gauge wire as you can with a 12 gauge wire.

    This is the point I was making is that bigger is not necessarily better. That a good 16 gauge wire can have a 100 foot run under an NTrak module set and still only drop .24 volts over the whole 100 feet. This is mostly due to the reduced reactance of the wire.
     
  4. ScaleCraft

    ScaleCraft TrainBoard Member

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    But...let's say you took an Ames Pill and tried Large Scale dcc and locos that draw 5 (five) amps under load...sometimes more....and the recommendation is 16GA. Bigger might be better, necessarily or naught.
    Yes, freq is higher, but so is the load, and I know in 0 on AC I use 14GA for feeders, 12 for commons, and I wouldn't dream of using anything as special as 8KC for that.
     
  5. flexeril

    flexeril TrainBoard Member

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    Is twisted important for a bus wire?
    I hope not!

    As for the gauge, help me out here.... 12 or 14. What is best?

    Sent from my iPhone using Tapatalk
     
  6. Doug Gosha

    Doug Gosha TrainBoard Member

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    By twisted, do you mean stranded or two wires twisted together? Stranded doesn't really matter. You can use either stranded or solid. Stranded is just a bit easier to work with. There is no need to twist two wires together although it may be more convenient.

    How long are your runs going to be? You certainly don't need 12 gauge wire for a typical layout. You don't really even need 14 gauge. 16 would be OK.

    Doug
     
  7. natsb

    natsb TrainBoard Member

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    It depends... I am new to DCC so I did a lot of study and Did a lot of testing on my track. I did the testing because of all the contrary advice on the web, so I wanted to see what was what with my own eyes.

    The bottom line was that the trains didn't care. They worked perfectly with or without the twist.

    The signal did care. The twisted bus produced a much cleaner signal. I have posted screenshots of my oscilloscope elsewhere to show the comparison.

    Therefore, it all boiled down to whether or not I cared about how pretty the signal is, because the trains certainly don't. It is my hobby, my track, and my peace of mind, so I twisted the bus to make me happy.

    There are too many different layouts using lots of different materials to pretend that my results can be applied across the board, so you need to do what works for your situation.

    It would be interesting to know if the dirty signal affects the life span of decoders, but that would be the topic for another tread.

    Sent from my LG-E980 using Tapatalk
     
  8. flexeril

    flexeril TrainBoard Member

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    Natsb,

    What gauge are u using?


    Sent from my iPhone using Tapatalk
     
  9. natsb

    natsb TrainBoard Member

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    I used 12AWG for the power bus. 20 and 24AWG for the feeders. 18AWG was used to juice the frogs because it was the smallest 3-wire cable I could find at the stores.

    Sent from my LG-E980 using Tapatalk
     
  10. flexeril

    flexeril TrainBoard Member

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    So for the frogs, u recommend 20 or 24?


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  11. natsb

    natsb TrainBoard Member

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    I would bow to the much more experienced folks here, but since a frog would draw very little power, a 20 or 24 would do fine.

    Sent from my GT-N8013 using Tapatalk
     
  12. Doug Gosha

    Doug Gosha TrainBoard Member

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    About the only way you may have trouble with 20 or 24 gauge for a frog is if the bus were about 100 - 200 feet away from the frog. The voltage drop would maybe be noticeable then.

    :D

    Doug
     
  13. subwayaz

    subwayaz TrainBoard Member

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    Hey Gentlemen let's play nice and please keep it simple for those of us who are new to DCC; like myself.

    Thanks
     
  14. flexeril

    flexeril TrainBoard Member

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    ?


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  15. flexeril

    flexeril TrainBoard Member

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    Thanks for the reply natsb


    Sent from my iPhone using Tapatalk
     
  16. mfm_37

    mfm_37 TrainBoard Member

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    20 to 24 will be fine for powering frogs. It will also work fine for track feeders if you have enough. I like every two to three feet or every piece of rail that is not slodered to a piece of rail with a feeder attached.
     
  17. Doug Gosha

    Doug Gosha TrainBoard Member

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    In rereading this thread, I want to apologize to David for my earlier snarky comment about using motor wire for a long run, etc. He was speaking in terms of the relatively complex signals involved in DCC and I was naturally (being I don't use DCC) thinking in terms of fairly uncomplex DC. Reactance will, of course, affect a DCC system much more than a DC system since the decoder relies on cleaner signals from the controller to work whereas a motor just needs voltage to run.

    My audiophile parody still stands, however. :D

    Doug
     
  18. ynono

    ynono TrainBoard Member

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