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how do I trouble shoot line noise ?

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  • how do I trouble shoot line noise ?

    The only thing I can think of is that I am getting some line noise. I am using Cat-6 to connect photosensors and all with 150 ohm 1/4 W resistors. typical pins 10-13 for sensors, 2 for relay and 15 for track call all going to separate ground pins 19-25 the relay on is on 25.

    I put an example of it in this video. The loud banging is me reaching over to hit the track call button with a stick.

    [YOUTUBE]U7ZFsyJo_xo[/YOUTUBE]

    I cant explain what's happening here. But if I do this, it works fine the rest of the day until I reboot.

  • #2
    First add a small capacitor across each lane, (ones like fitted to SCX cars to stop TV interferance work fine)
    Is this on an Ardunio setup or straight to the Parallel port?
    If to an Ardunio add a ferrite core to the USB lead.

    this is what Rusty on Auslot did.
    1. Fitted '104' ceramic caps (Same as on a SCX motor) accross the rails on each lane.
    2. Fitted 200uF capacitor between ground and +5v on the Arduino to reduce brown outs.
    3. Grounded an unused, but wired up, 4th lane input.
    4. Fitted a ferrite core to the sensor harness.
    Last edited by Phil Kalbfell; 06-21-2015, 07:38 AM.

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    • #3
      Originally posted by Phil Kalbfell View Post
      First add a small capacitor across each lane, (ones like fitted to SCX cars to stop TV interferance work fine)

      Is this on an Ardunio setup or straight to the Parallel port?
      this one is Parallel port.

      I will try adding a capacitor to each lane today, I think I have a ton of the in a box somewhere.

      update: turns out I do not have any. I might need to look on the auction site for some.
      Last edited by jeremycobert; 06-21-2015, 08:33 AM. Reason: update

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      • #4
        I think Scalex also have a capacitor on the motor leads.

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        • #5
          My installation uses a Trakmate card and a 0/0/4 phidget card. I fitted a ferrite core to the sensor harness, Phidget card USB cord and the Trakmate serial cord. No issues of any kind.

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          • #6
            Like madman I only use the ferrite core, But that is not always the fix, adding the 104 caps near the sensors and the core seems to fix the problem.
            The Ardunio boards seem to be more sensitive to the problem.

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            • #7
              I added capacitors to each lane. that did not work. I am going to have to keep looking into this.

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              • #8
                Where are the capacitors located? They should be as close to the computer as possible. You could also try adding ferrite cores like Scalextric uses.

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                • #9
                  Originally posted by RichD View Post
                  Where are the capacitors located? They should be as close to the computer as possible. You could also try adding ferrite cores like Scalextric uses.


                  Sometimes get random signal for false lap and suspect noise as the cause. Can someone give a dummies guide for what type of capacitors to use and how to attach to the lanes please?


                  Also would it help for noisy cars to attach the capacitors to the motors similar to what I see in the majority of new cars?

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                  • #10
                    I have used capacitors cut off SCX cars and just attached them across each track feed.
                    Also ensure each sensor ground wire goes back to board or plug.
                    May help knowing what sensors, interface and software you are using.
                    Last edited by Phil Kalbfell; 01-07-2017, 08:33 PM.

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                    • #11
                      Using a light bridge and some 3du5c light transistors in the track. Signal goes bacl to an Arduino board via a cat6 shielded cable and from the Arduino to the pc on a 20cm USB cable. PC is running Race Coordinator.

                      Never see the issue on Carrera/Scalextric cars, seems to be mostly the older Fly cars. Perhaps I just need a capacitor on the motors in them.

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                      • #12
                        The capacitors across each lane should fix the problem on all cars.
                        Does the USB cable have a Ferrite core on it?

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                        • #13
                          Hi, yes the USB cable has a ferrite core and is a good quality cable. Also length is very short to reduce any noise to it.


                          For the capacitor across the tracks, I assume this is one capacitor per track and one leg to each rail? Any specification capacitor? Would assume a 50v would be sufficient, but what uf?

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                          • #14
                            Had similar problems with a bad ground on the power cord of the computer. I was using an adapter to plug a 3 prong into old house wiring 2 prong

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