Kato Unitrack N Scale Track Discussion

Hardcoaler Jul 6, 2017

  1. Hardcoaler

    Hardcoaler TrainBoard Member

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    A quick few questions please. Are the tracks insulated from one another on Kato crossing components? In other words, is the yellow track insulated from the orange track in the picture below? Also, does the track component carry the current through to the opposite side (between A and B and between C and D) or will I need to wire the opposite side? Thank you.

    upload_2018-5-17_10-27-42.png
     
  2. RBrodzinsky

    RBrodzinsky November 18, 2022 Staff Member TrainBoard Supporter In Memoriam

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    Yes and yes. There is no electrical connection between the two tracks; and the four short rails inside the diamond are electrically connected to the rails, on both sides, from the unijoiners.
     
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  3. Hardcoaler

    Hardcoaler TrainBoard Member

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    Thanks Rick -- should be a piece of cake to put in place then.
     
  4. Hardcoaler

    Hardcoaler TrainBoard Member

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    I've read various posts on wire gauges and am more confused than ever about what to use on my DC Unitack layout. The longest wire run I can possibly imagine would be 8 FT to a track feeder or turnout. Most will be half that. I normally run double-headed diesel power, but sometimes three units. Most of my locomotives are from the mid-1980s to mid-1990s, so they might pull a bit more amperage than newer products.

    Kato uses 24 Ga for track feeds and 26 Ga for turnout control. If I were to move to 24 Ga for both, would that suffice or would 22 Ga or 20 Ga be a better bet?

    I'll have nearly two dozen turnouts and a dozen blocks in a two-table layout that will be moved someday, so would like to avoid pulling and fighting with heavy gauge wire if possible. Thanks y'all! (y)
     
  5. drbnc

    drbnc TrainBoard Member

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    At 8 feet, 24 gauge should be fine. Stranded for flexibility. 20 gauge would be better, but you still have to join to the 24 ga. that Kato supplies, so it's kind of pointless (at 8 feet max).
     
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  6. NorsemanJack

    NorsemanJack TrainBoard Member

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    I would be shocked if it would make any difference for turnouts. For track feeders, your only concern is voltage drop. There are online calculators that will provide a reasonable estimate of how much voltage drop you'll experience based upon length and gauge of wire. I personally run 16 gauge for feeders on my small DC Unitrack layout and only drop down to the smaller gauge for that final length of the Kato feeder wire. Since you're using blocks, you could "see" a voltage drop as a train passes from one block (with a shorter circuit path) to another block (with a longer circuit path).
     
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  7. Hardcoaler

    Hardcoaler TrainBoard Member

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    Thanks Norseman. I found a calculator and these results for 12VDC @ 1 AMP for 8 FT:

    20 Ga = 11.798 volts (1.7%)
    22 Ga = 11.679 volts (2.7%)
    24 Ga = 11.489 volts (4.3%)

    Looking at the results, I'm thinking that the powerpack will certainly be able to overcome any of these voltage drops.

    Thinking about a voltage drop transitioning from one block to another, I looked at 24 Ga wire 8 FT Long and 4 FT Long, I see that a block fed by a 4 FT wire would have 11.745 volts present and a block fed by an 8 FT wire would have 11.489 volts for a difference of 1/4 Volt (0.256). I wonder if that would be noticeable? With 22 Ga, it shrinks to 0.16V and with 20 Ga it's only 0.10V.
     
  8. NorsemanJack

    NorsemanJack TrainBoard Member

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    Hard to say. An unconventional approach might be to still use 8ft of wire for that four foot run. That would somewhat equalize the voltage drop. You could also use a higher gauge wire for the shorter runs, and run the calculations. The drop would likely vary by current, so that might not work as well.
     
  9. Hardcoaler

    Hardcoaler TrainBoard Member

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    That's a novel approach to equalizing the differences that would probably work. Alternately, I could also use track feeder wires of different gauges in recognition of their length to engineer a uniform voltage drop for all blocks …. assuming a consistent amp draw.

    Although, I continue to think about drbnc's comment that connecting a larger gauge feeder wire to Kato's smaller 24 Gauge factory wire for track connection likely nullifies gains, much like using a 5" water pipe to feed a lawn sprinkler, but having to neck it down to a garden hose-sized outlet just before the sprinkler.

    This is all interesting stuff. I can't think of many other hobbies that combine as many elements of design and engineering as model railroading, especially with all of the aspects of creativity and handwork we combine in the process.
     
    Last edited: Jun 21, 2018
  10. NorsemanJack

    NorsemanJack TrainBoard Member

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    I don't believe this is true (without getting into the fluid dynamics). A large feeder with a final short length of small wire will not result in the same voltage drop as a full length of the smaller wire.
     
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  11. pdavidson

    pdavidson TrainBoard Member

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    I ran 14ga buss wire and tried to route it so that it was always within reach of the Kato 24ga feeders. Tried to minimize the amount of 24ga feeder wire. I never extended the 24ga feeder beyond the stock length and always cut it off shorter when possible so that it was no longer than needed to reach the buss. Only a few are the stock length. Most are around 12 inches or shorter. My consist are typically made up of 4 locos and have had no problems of evidence of voltage drops. However, all my locos are recent vintage. No really old stuff that might draw excess current.
    As far as the Kato turnout control wire, just about anything will work. That wire carries a pulse...not a constant current.
     
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  12. Carl Sowell

    Carl Sowell TrainBoard Supporter

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    NJ,

    I agree with you that we can not compare the electricity voltage issue to the fluid dynamics.

    In the case of the question wouldn't the smaller wire at the end of a long or short larger gauge become warm or maybe hot by forcing the voltage and amperage through that smaller diameter ? ? You can tell that I "no savy" electricity.

    Carl
     
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  13. NorsemanJack

    NorsemanJack TrainBoard Member

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    LOL. Voltage isn't an issue. It is only current. The poster said he was running DC, so it's highly unlikely that the amperage would ever be an issue; even with 24 gauge wire. Besides, a short length of warm wire is unlikely to ever cause a problem.
     
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  14. NorsemanJack

    NorsemanJack TrainBoard Member

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    I spotted this today on Kato's Japan web site:

    https://www.kato-smartcontroller.com/

    Looks like we'll soon be able to use our iPhone to run the railroad! (there must be an app for that....) (y)
     
  15. Roger McCarty

    Roger McCarty TrainBoard Member

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    In this situation Voltage drop occurs as a result of resistance and is independent of current drawn, basic Ohm's law.


    Voltage drop can be an issue because the lower voltage will reduce the RPM speed of the motor which ultimately affects the speed of the loco. If the voltage drop is great enough, you will hear a change in motor pitch as well as observe the speed change.

    [edited per request]
     
    Last edited by a moderator: Jun 26, 2018
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  16. NorsemanJack

    NorsemanJack TrainBoard Member

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    Except.... At higher currents, the conductor will heat up, and increased temperatures increase the resistance of the conductor. Ohm's law still applies, but an increased voltage will be required to sustain the same current.
     
  17. Hardcoaler

    Hardcoaler TrainBoard Member

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    Thanks again everyone for furthering this discussion -- good thoughts here. I might do a few simple experiments on the floor (since I don't have benchwork yet) with two blocks and see if there's any noticeable fluctuation as a three unit set crosses the gap.
     
  18. Roger McCarty

    Roger McCarty TrainBoard Member

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    While it is true that a conductor's resistance does increase with temperature, the increase is very very small. We are not operating in conditions which would trigger a thermal runaway.

    In a case where the resistance of the conductor increases, the voltage supplied for the current drawn will decrease due to the increased load on the power supply. Current drawn will remain essentially the same, but the voltage supplied will decrease. This voltage drop is due to the increased load resistance.

    Our power supplies don't increase the voltage to sustain a level of current. They deliver the amount of current drawn and do their best to deliver the voltage dialed-in. Resistance changes ultimately affect the voltage available at the loco. Increased resistance will result in voltage drop.
     
  19. Point353

    Point353 TrainBoard Member

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    So what does MRC's "Accutec Technology" do?
     
  20. Maletrain

    Maletrain TrainBoard Member

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    Well, no, that is wrong.

    Ohm's law is V = I x R. That is, the voltage drop across a resistance is directly proportional to the current flowing through it (and the value of the resistance). So, the voltage drop in a wire of resistance R is going to depend on the current flowing through that piece of wire.

    That has nothing to do with the temperature of the wire increasing, and causing increased resistance. Circuit components (like incandescent light bulbs) that have increasing temperature because of the power dissipated in them by flowing current are called non-Ohm's law resistors. Those types of components typically reach some sort of equilibrium in current, electric power dissipated, and heat dissipated so that the current and temperature quickly become constant. So, for instance, an electric light bulb can be rated in watts of electric power (W = I x V) at a particular voltage (V), because they limit the current (I).

    Some model train short circuit protectors work on that principal by inserting a 12 volt light bulb in the power feed circuit. At the small current drawn by a typical N or Z scale locomotive, the current through the bulb filament does not heat it up, so the voltage drop is insignificant and the train runs. But, if the train creates a short circuit, the current tries to increase and the light bulb filament heats up and increases resistance to the point the the short circuit on the tracks can only draw something like 1 or 2 amps.
     

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