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Maximum distance between potentiometer (for analog input) and motor controller — Parallax Forums

Maximum distance between potentiometer (for analog input) and motor controller

BlakeBlake Posts: 74
edited 2009-12-02 22:17 in Robotics
Hello,

I think I have a relatively simple motor controller related question:

I am trying to hook up a 12 volt, 6 amp Dayton brushed motor with a unidirectional motor controller (I am thinking Critical Velocity Enterprises' SPD-315-D criticalvelocity.com/products/datasheets/spd-315-d.pdf). This motor controller can use an analog input signal from 0-5volts varied with a potentiometer. I am pretty inexperienced with this, but I think the motor controller provides 5 volts on-board which is then varied down with the pot and sent to an input pin on the controller.

All of this I'm okay with. My application however requires my potentiometer to be 350 feet from my motor controller. In other words, I want to activate the motor controller and thus the motor from a 350 foot distance using a potentiometer. The purpose of the motor is to wind in slack on a wire with a specific amount of pull, which can be made stronger or weaker depending on the potentiometer.

Can it be done?

I would like to use 18 guage wire for the "tether" between the pot and controller. I am thinking of using a 1k wire-wound single-turn pot. Does anyone have experience in sending analog signal to a motor controller over such a long distance through a wire (i.e., not radio-transmitted).

Any help/advice would be awesome,

Thanks,
Blake

Comments

  • allanlane5allanlane5 Posts: 3,815
    edited 2009-12-02 20:32
    350 feet of wire have quite a bit of resistance. As well, it could pick up a lot of noise -- 350 feet makes a good antenna.

    Doesn't Dayton, or Critical Velocity, have a solution to this issue?
  • BlakeBlake Posts: 74
    edited 2009-12-02 21:12
    after a phone call to critical velocity, they are under the impression that using a low ohm pot and capacitors to smooth out the noise would probably accomplish the task... but, any other opinions?
  • ercoerco Posts: 20,256
    edited 2009-12-02 21:29
    Makes me appreciate the accomplishments of the developers of wire-guided missles and torpedoes. Up to 2.5 miles of control wire that has to pay out at very high speed!

    http://en.wikipedia.org/wiki/Wire-guided_missile




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    ·"If you build it, they will come."
  • BlakeBlake Posts: 74
    edited 2009-12-02 21:35
    I guess my question really is, "has anyone in this forum actually done something like this with acceptable results?"
  • Beau SchwabeBeau Schwabe Posts: 6,566
    edited 2009-12-02 22:17
    Blake,

    Due to antenna effects mentioned earlier, I would lean more with the idea of having a digital potentiometer that is local to your controller and program it serially at 350 feet.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
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