dc motor control

Discussion in 'The Projects Forum' started by takeitapart, Jan 31, 2011.

  1. takeitapart

    Thread Starter New Member

    Jun 20, 2010
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    I have come across this circuit for a simple dc motor control. Does anyone have any input. I need something simple for speed control. high precision is not needed. Thanks.
    DCmotor.jpg
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    The image is too small to see, and you have not provided any info about your motor or supply voltage.
     
  3. takeitapart

    Thread Starter New Member

    Jun 20, 2010
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    Is there a "best way" to post the circuit. I scaned it from the article. I can redraw it and scan again? Or another method?
     
  4. gerty

    AAC Fanatic!

    Aug 30, 2007
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    What voltage/current does your motor require. That drawing shows 120v ac going through a bridge rectifier. Very dangerous..
     
  5. takeitapart

    Thread Starter New Member

    Jun 20, 2010
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    It is a 90 volt dc dayton motor. I do not have the current requirements with me. I was going to use it on a grinder in a home shop. Why "very dangerous"
     
  6. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Check post by hobbyist, right now two posts below yours. He is using 90V PM motor with a SUS trigger; schematics almost the same. The DIAC will trigger at about 28V & SUS adjustable, as shown about 10V. An isolation transformer will keep from having a " hot chasis".
     
    Last edited: Jan 31, 2011
  7. takeitapart

    Thread Starter New Member

    Jun 20, 2010
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    I hope this is a better image. My motor is a 90volt 1amp continious duty permanent magnet motor. This circuit came from "The Home Shop Machinist" Charles Eyer 1996. The idea was to use a dc lawnmower motor on machine tools for speed control instead of belts. I was wondering if it still is viable or is there another equally simple cuircut that can be used?
    circutit.jpg
     
  8. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    The circuit is simple & should work. I would connect motor to moving SW contact, fixed to R2 & B1+, other SW to black 115 AC line along with a 10A fuse. Ground motor frame & chasis if metal. Remember all of the accidents back in the 1950s when when we had high V series string filaments & hot chassis; be carefull if not using isolation transformer.
     
  9. takeitapart

    Thread Starter New Member

    Jun 20, 2010
    21
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    What is a moving SW contact? If you have any other simple designs I am not commited to this one. How would an isolation transformer fit in?

    Thanks for the input!
     
  10. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Not pretty, but I hope it helps: The transformer willnot make ckt work any better, but adds a bit to safety, @ 150W, probably expensive. There are a lot of appliances that use two wire cords & no transformers, but are designed to keep wandering fingers away from hot circuits.
     
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