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what is a servo?

Discussion in 'General Discussion' started by chapsrlz, Sep 10, 2014.

  1. chapsrlz

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    hi guys!

    i've read a lot about "servos" googled, looked in the wikipedia and seen a lot of servo images (all serving different purposes) but i cant find a direct answer to what a servo is,mor what the word stands for.

    can you explain me, plain and simple what a servo is.
    thanks!
     
  2. HarryT

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    It's simply a device that converts an electrical impulse into a mechanical action - typically rotating a wheel to a position specified by the electrical signal. This movement could be used to press a camera shutter, raise or lower landing gear, move the control surfaces of an aircraft, etc.

    "Servo" is short for "servo motor".
     
  3. MadMitch88

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    This might be a cool place to start learning about servos:


    [youtube]https://www.youtube.com/watch?v=D-QTSghkqVk[/youtube]
     
  4. KwadKopter

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    Good video. 22 second intro is absurd.
     
  5. Suwaneeguy

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    In simpler terms, a servo is nothing more than a switch that responds to a radio signal.
    The switch can activate any number of devices, depending upon how it is set up.
    The video shows how a simple servo can cause movement of something, such as a rudder.
     
  6. ProfessorStein

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    Actually, a servo has nothing to do with a radio signal. Harry's description is more correct. If the action is controlled by a radio signal, the radio signal has already been received by the receiver, interpreted by the control circuit, and converted into the proper electrical impulse to drive the appropriate servo.

    But the servo is completely independent of the radio signal itself. There are plenty of examples of uses of servos in non-radio-controlled applications.
     
  7. Wedeliver

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    As a kid I used servo motors in Erector sets. They are controlled as stated above by electric means, as the ones I used when I was a kid ran off of maybe C or D type batteries. We used them when you might build things like an elevator or conveyor, things like that.

    Recently I had to put a servo motor in a P 2 Vision to replace a missing one, it controls the tilt function on the Phantom 2 Vision Camera.
     
  8. chapsrlz

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    thank to all for your responses.

    crystal clear what a servo is :)
     
  9. Suwaneeguy

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    Dear professor, I was relating to RC servos as the person was asking about.
    I did not go into the 30,000 pages of detail needed to explain it thoroughly as that answer is not within the scope of this forum.
    You want a basic answer, I give you one. I do not feel it necessary to get into all the inner technicalities.

    Did you watch the video?
    Explain how the servo responded to the controller stick when the servo was not even attached to an aircraft.
    Ergo, the servo is a receiver and cares less what it is attached to.

    Yes there are servos elsewhere in the real world that operate without radio waves.
    But that is not what the original question was asking about.
     
  10. Mike

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    It was attached to an RF receiver.

    Yes, it is a receiver, but only of electrical signals, not radio waves.
     
  11. HarryT

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    No, the servo is not a receiver. The servo is plugged into a radio receiver. It's the radio receiver that receives the radio signals, not the servo.

    All servos "operate without radio waves". As has been said, servos do not themselves receive radio signals.
     
  12. N017RW

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    What a servo is, how it works, etc. is not a philosophical question. It is well defined and documented.

    There is TONS of on-line information which will eliminate the errors of context and/or other miscommunications or misunderstandings. Not sure how the OP missed it.

    No need to argue about it here.
     
  13. ProfessorStein

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    I might buy that argument if your description (which is inaccurate) was any shorter than the one HarryT posted 3 posts above yours which described a servo perfectly. This proves that you do not need "30,000 pages of detail", nor was I suggesting that you should've included it. But if you are going to shorten it to a more digestible 200 words or so, at the very least those 200 words should be accurate. And by beginning your description with "in simpler terms...", you give the impression that you are ignoring, if not out-and-out refuting the descriptions before yours (including Harry's... which is accurate and deserved no refuting).

    I did, in fact, watch the video. I'd seen it before, but watched it again when Mitch posted it above. Other than the stilted presentation style of Mr. Weekly, it's an excellent video. As far as me "explaining how the servo responded to the controller stick when the servo was not even attached to an aircraft"... no one ever said a servo must be attached to an aircraft. But if you look closely, the orange wires leading to the servo are clearly visible at the bottom of the video. These wires are attached to, you guessed it, an RC receiver attached to a control circuit board. In your own words... you wanted a basic answer, I give you one.

    In short, servos themselves do not operate on "radio waves". None. Period. They all have to be attached to a receiver and a control board if they are to be used in an RC situation (there are some control modules that have a servo and a control board, maybe even a receiver, built into the same housing, but the servo is still just one component). And to describe them any other way does a disservice to the thread and the OP. What if the OP had taken your description literally, run out and bought a servo, and then wondered why it wasn't responding to the radio control he was trying to use to activate it? Nowhere in the OP is there a question about radio controlled servos, specifically. In fact, the question seems very much more about servos in general.
     
  14. Mori55

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    It plugs into a receiver. Used in Rc products forever.
     
  15. Wedeliver

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    Soo, I was reading through 31,000 pages of, I'm not really sure, something about the skateboards. but, I have a question. This comes from an old guy, although to really honest I don't feel much different then I did when I was young and I am still trying to figure out what I am going to do when I grow up.

    But, enough rambling, my question is.trying to keep it simple. "A servo is an electric motor with controlled, limited movements"

    although I don't think I know what I am talking about.. gonna hit submit anyway...lol