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5 wire servo

  1. May 13, 2009 #1

    I am supposed to build a controller for a 5 wire servo. I'm having trouble finding information online that appeals to electrical engineering folks.

    What are the 5 wires? I suspect there is power and ground, but that leaves 3 unknown connections :eek:

    I have a basic understanding of servomotors (though, by no means complete), to the point where I can get a handle on the application circuit in the following datasheet:


    Maybe someone can help me understand what the 5 connections are in terms of the above circuit? Do you think it would be possible to make a basic controller with a PIC uC?

    I know this post is kinda vague, so thanks for any thoughts or help.
  2. jcsd
  3. May 13, 2009 #2
    The five wire motor is a stepper motor. It's composed of a number of electromagnets that have to be activated in sequence to rotate the shaft. And you need a special driver for that too.

  4. May 13, 2009 #3
    Hmm, I don't think it's a stepper. From my experience, you can usually turn a stepper in your hand without much physical resistance. You don't get that dynamo charging sound like you do when you turn a servo. (I get the servo sound, on this one.)
  5. May 13, 2009 #4
    Never mind, forgot some servo motors have error correction for a feedback loop.
  6. May 13, 2009 #5
    I think I might give up on this one. The servos are part of an xyz stage, which is supposed to come with a controller (both the stage and controller are made by the same company). Well, the controller has been missing for many years.

    My thought is that the interface is somewhat proprietary; they probably don't want you to figure this one out ;). Thoughts on this?
  7. May 13, 2009 #6
    The 5-wire synchro-resolvers ("servos") I have used had two wires for ac power and return, and the other three wires transmitted/received a 3-phase angular position signal to/from the other synchro. Either synchro could be used as a sender, and the other as a sender. We would put a hand crank on one and the other synchro would follow. I have never used more than two connected together.

    Edit: These units were also called selsyns. See Figure 2 in this for wiring diagram:
    Last edited: May 13, 2009
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