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  1. #1
    RC Qualifier
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    Servo Signal "missing"

    Please forgive me if this info is readily available. I've had little luck finding it

    Would someone please tell me what will happen if I lose the signal between the receiver and a servo, but still have the power applied to the servo?

    I am at work so I cannot experiment

    Will the servo....

    Hold its' last known position?

    Return to zero/home?

    Implode in a firey mass of smoke?

    I'm sure someone here has tried,experimented, or experienced this. I've been to several "how does it work" sites. I am also familiar with how servos and their controllers function in a manufacturing environment, but only in specific applications.

    Thanks in advance
    Last edited by Mayberry Kid; 09-28-2012 at 04:02 PM. Reason: spelin'
    The Kid

    14.4 Dewalt & Misc. el-cheapo mods

  2. #2
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    i think it should return to it's neutral point as its not getting a signal. It shouldn't be locked in the last known position as it needs a signal to keep it there, Unless that was the neutral point and maybe hard to turn with just the power to it. It won't go up in a mass of smoke.
    But then again, i've never tried to do it.
    Guide books aren't part of the packaging.

  3. #3
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    But it also needs signal to return to center... that is why it would stay where it was at.
    BUT, if this is a steering servo; the tires would be able to move the servo wherever they want. It would be just like as if the RC was off, because the power goes through a controller that is operated by the signal.

    Hope that makes sense.
    ~J
    Whatever it is I just typed... could be wrong.

  4. #4
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    thats the bit that confused me the neutral signal for the servo would be like disconnecting that wire thus returing to the servo neutral point, as opposed to sending a signal to the servo then disconnecting the wire at that point which locks it at that point
    Guide books aren't part of the packaging.

  5. #5
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    If the signal for return to center was like "turning off" the signal wire, this would be the case; but that is not how a servo works.
    Whatever it is I just typed... could be wrong.

  6. #6
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    I think i got it,
    using a pot when the pot is at neutral the servo turns to neutral as it still sends a signal that is the neutral point.
    cut the signal wire at any degree of movement the servo doesn't recieve no more signal therefore staying where it is and not turning forward or backward as the servo isn't been told to move.
    Guide books aren't part of the packaging.

  7. #7
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    Yes!

    Whatever it is I just typed... could be wrong.

  8. #8
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    Exactly as I thought, now for part two

    I am asking BC I have a big'ole fluffy idea that I'm most likely going to try

    Do you think the servo will "hold" since power is still applied??
    Or, as you said in post #3, the servo would get "driven" by the wheels and bump steer to wherever that might be??

    In an RC, the servo listens for instructions and then does its' best to carry them out (position wise). Simply one way communication. Thats where it gets foggy for me, I did not know what happened with a lost signal. Nor do I know how the servo acts once that signal is gone (and power is still there).

    In a manufacturing environment, where $$machinery$$ and $$product$$ are concerned. There are Hall effects and absolute position encoders (among other things) that give direct feedback to the controller. Once a servo(or servo motor) stops, slows, speeds, or strays the equipment will E-stop, or go to a safe position depending on what is designed into the machine

    Thanks for all of your feedback and please let me know if you think the servo will "hold" or "drift"
    The Kid

    14.4 Dewalt & Misc. el-cheapo mods

  9. #9
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    I am pretty sure it will drift...

    One way to test (easy too) is to use a sharp knife to pull out the signal wire from a servo. There is a little plastic tap holding a metal bit in the Futaba J connector. When you carefully lift this tab and gently tug on the wire, it should slide right out. If done properly, this is 100% reversible.

    Plug the servo connector into channel 3...
    Plug the bare connector into channel 1 on the signal post/pin...
    Use the radio (the system needs to be powered up now) to turn the servo...
    Then unplug the signal wire.

    What happens?
    Whatever it is I just typed... could be wrong.

  10. #10
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    Thank you Jimmie
    I will play tomorrow night,if I can get off of these long hours
    The Kid

    14.4 Dewalt & Misc. el-cheapo mods

  11. #11
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    Soak it up while you can!
    They don't last forever.

    I would do it to test... no time here either. lol
    Whatever it is I just typed... could be wrong.

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