Playing with DCC++...quick question

french_guy May 14, 2018

  1. french_guy

    french_guy TrainBoard Member

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    I want to try DCC++ with Arduino Uno and motor shield
    To be clear, if I power the Arduino with 12V (no more), I don't need to power the motor shield (screw terminal) nor cut the trace on the PCB, is that correct ?
    Thanks
     
  2. sachsr1

    sachsr1 TrainBoard Member

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    No the motor shield needs to get 12 volts separate from the Arduino. The Arduino can't supply 12 volts or the current needed through the pins. You can split the 12v wire and power both from one source. You'll still probably want to cut the trace but I think you can put 12v into the VIN pin???
     
  3. french_guy

    french_guy TrainBoard Member

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  4. Quax

    Quax TrainBoard Member

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    The motor shield must be powered in any case. When the traces are not cut, then the motor shield supplies power to the Arduino board. In this case, you don‘t need a separate power supply for the Arduino. But if you want more than 12 volts on the track, you should consider a separate power supply for the Arduino to not exceed the Arduinos Vin specs.
     
  5. sachsr1

    sachsr1 TrainBoard Member

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  6. french_guy

    french_guy TrainBoard Member

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    What is the right voltage for N scale?
     
  7. Quax

    Quax TrainBoard Member

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    Regarding the brake traces: You can cut them to make the relevant pins available for individual use in your project.
    But: If some day a Railcom/BiDiB feature is added to the project, the brake lines may be needed for this purpose.
     
  8. Quax

    Quax TrainBoard Member

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    I'll leave the answer to this question to the N scalers here. From what I have heard, you don't need more than 12 V for N scale.
     
  9. french_guy

    french_guy TrainBoard Member

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    No N-scalers here apparently.................:cry:
     
  10. SP_fan_1951

    SP_fan_1951 TrainBoard Member

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    You will only need 12V if you are running bullet trains;), for any reasonable speed, 10 V track voltage is plenty, so a 12V supply will work just fine. A 2 Amp supply will be adequate. The driver board is probably going to be the limiting factor there. If you are running a large layout with more than 10 loco's running at the same time, you will probably need to add boosters and a larger power supply. The power supply you are looking at will not only power the track, but probably your LED lighting, accessories, and everything else as well.
     
  11. sachsr1

    sachsr1 TrainBoard Member

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    The link I shared showed 12v to be okay for n scale but I was hoping that an actual n scaler could confirm
     
  12. RCMan

    RCMan TrainBoard Member

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  13. Trusty

    Trusty TrainBoard Member

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    Hi compatriot. For this kind of question about DCC++, I can just encourage you to ask it on the forum of the site Locoduino (French spoken only), the best French source about DCC++ usage.

    Bonjour compatriote. Pour ce genre de question, je ne peux que te recommander le forum du site Locoduino à la pointe pour l'utilisation de DCC++ en France...
     
  14. french_guy

    french_guy TrainBoard Member

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    Hi
    Got my answer from TrainBoard, not problem
    I've discovered Locoduino on another post though, and I find it very nice. I may try their solution as well
    Thanks
    By the way: where are you located?
     
  15. Trusty

    Trusty TrainBoard Member

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    Melun, 40Km from Paris
     
  16. TwinDad

    TwinDad TrainBoard Member

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    Actual N-scaler here.

    12V is nominal for N scale, and is the "official" output voltage of Digitrax boosters for N scale. Somewhat higher is acceptable. 10V is fine, and (as Mr. Gurries says) arguably better than 12V. Below 10 at some point the decoder may start getting wonky depending on how its voltage regulation is done.
     
  17. french_guy

    french_guy TrainBoard Member

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    Never went to Melun, but I know the name for sure.....I used to live in Compiegne, but moved out of France to the US in 2005, then Brazil and back in the US. I live in Michigan (1 hour north of Detroit)
     
  18. french_guy

    french_guy TrainBoard Member

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    I will have to check the voltage of my power supply under load........Have a new multimeter arriving today
     
  19. John W Zerbe

    John W Zerbe TrainBoard Member

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    Also an N-Scaler here. You can run it on 12v and I did for a while. My atlas locos ran slower than they would on my N scale dc power supply. I switched to 15v to the motor shield and get more comparable performance.
     
  20. TwinDad

    TwinDad TrainBoard Member

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    Because of the way DCC driven motors are controlled, the voltage isn't necessarily as important as it may seem. Because the motor is under PWM control by the decoder, the track voltage has very little to do with the (effective) voltage applied to the motor. It does set a maximum, but under normal conditions this doesn't matter. It's rather the opposite of DC... under DC control, the voltage controls the speed. Under DCC control the speed (throttle setting) controls the voltage (at the motor) regardless of the track voltage.

    If you are running your locos at anything close to prototypical speeds, you can probably use significantly higher track voltages with no worries because you are not applying much current to the motor. It won't (or shouldn't) get hot. The decoder itself, if NMRA compliant should be fine up to 24V or so, and as long as the motor stays cool it will be fine at any reasonable voltage.

    Now, if you tend to run your locos at full throttle, or place them in conditions where they may stall out frequently, then there will be trouble. And the manufacturers will generally make recommendations based on the stall conditions because they want to ensure happy customers and no fire hazards.

    Fault conditions should be handled (quickly) by the circuit breakers and other protection devices in your system. The loco's motor should not be the weakest link in the system.


    All that to say, the important thing is... are your motors getting overly hot? If they are, then either run them slower or lower the track voltage. If they aren't getting hot, you probably don't have anything to worry about.
     

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