Circuit Help - D/C Motor to move to specific points

Discussion in 'The Projects Forum' started by BGrisinger, Mar 14, 2011.

  1. BGrisinger

    Thread Starter New Member

    Mar 14, 2011
    2
    0
    I'm new to electronics and I'm looking to create a circuit that will essentially mimic the way a windshield wiper works. A wiper motor is much to big for my application.

    Essentially, I need to have an arm start at a specific position, move 90 degrees, stop and return to the start position. It needs to be relatively fast (between 50 and 60 lifts) per minute.

    I currently have a 3V dc motor which easily pushes the load I need it to move. I previously tried using a cam that rotated in a complete circle but the space I'm working in is too small to provide enough movement.

    Any help or ideas on how to create this would be greatly appreciated. Thanks in advance!
     
    Last edited: Mar 14, 2011
  2. shortbus

    AAC Fanatic!

    Sep 30, 2009
    4,019
    1,542
    People have a mistaken idea of how wiper motors work. Even though the blade arms move through a roughly 90* arc, the motor moves in a complete circle. There is a crank pin off-center on the motor that moves a linkage to make the arms move the correct arc. http://auto.howstuffworks.com/wiper1.htm

    Instead of a cam you would need to use a disk/wheel hooked to the motor shaft and a pin offset from the center enough to give the amount of movement needed and a connecting rod from the pin to the load.

    Another way is called a 'Scotch Yoke' here is a short video; http://www.youtube.com/watch?v=hsaoTo1vuY4
     
    Last edited: Mar 14, 2011
  3. BGrisinger

    Thread Starter New Member

    Mar 14, 2011
    2
    0
    Thanks for the response. Now I need to figure out how to build this.
     
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