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speed sneosr having analog output — Parallax Forums

speed sneosr having analog output

erfanerfan Posts: 3
edited 2012-07-02 09:53 in Robotics
Dear members,
Would you please let me know if you any speed sensor having analog output. I need it for a closed-loop controller to control a small dc motor. Many thanks for your time.

Comments

  • Tom CTom C Posts: 461
    edited 2012-07-02 03:47
    erfan,
    You can use a small dc motor as a generator. It will produce a voltage proportional to the speed of the armature.
    Just a thought.
    Regards,
    TCIII
  • erfanerfan Posts: 3
    edited 2012-07-02 04:11
    Dear Tom,
    In this case I need to couple the shaft of the generator to my motor. As they are small, it is difficult. Furthermore it can act as a load for my motor. Is it correct?
  • kwinnkwinn Posts: 8,697
    edited 2012-07-02 09:53
    A reflective sensor may work. Use a marker to darken one side of the shaft and aim the sensor at the shaft. Use the signal to trigger a one shot (555 timer) that charges a capacitor. The output voltage on the capacitor is proportional to the speed.
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