5v USB board connection to high powered devices

Discussion in 'The Projects Forum' started by adam763, Feb 27, 2014.

  1. adam763

    Thread Starter New Member

    Feb 27, 2014
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    Hi there, here's my first post (of many, I assume) currently, I require any helpful information regarding connection of high powered devices to a 5v USB controller. P.S. I'm a total noob, so please don't reply in tech-speak, if possible.

    OK, I have a USB controller board, designed to power 5v LEDs. I'm told that if I want to connect 12v devices or devices that run at more than 500mA, I should link all "+" points (of the devices) to a single 12v supply and not to the USB boards + outputs. "-" outputs are connected to the board to allow communication. This all makes perfect sense to me as I have tried a similar project to this before.

    However, I wish to use (for example) 12v 2A solenoids and step motors. Could I connect these up to the board as mentioned above, or would I need to use diodes, relays, etc? -I presume I do?

    And, if so, which diodes would I need? 500mA or 2A?

    I really don't want to melt my USB board or break my computers USB ports by getting this wrong.

    Thank you sooo much in advance.
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    might help to actually provide a link to this "usb controller board" you speak of.
     
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Use a an external power supply with a chassis ground. An ATX power supply converted to a bench power supply works well.
    Supply the 12 volt device with this supply.


    Then you can use the 5v USB to control logic level N-MOSFET transistors (5v connected from source pin(-) to gate pin (data pin of some controller connected to USB). Then place your stepper motors between the drain pin on mosfet and 12v power rail.

    The motor will be energized when the data pin goes to 5v and not energized when data pin is at zero volts.
     
    adam763 likes this.
  4. adam763

    Thread Starter New Member

    Feb 27, 2014
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    of course: http://www.ultimarc.com/pacdrive.html



    Thanks GopherT, I'll have a quick Google as some of the terms you've stated seem a little foreign to me (total noob alert). And if I'm still struggling, I'll post again.
     
  5. adam763

    Thread Starter New Member

    Feb 27, 2014
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    In response to my Googling, I've found this video that explains your text perfectly.

    Thanks again for your reply, without it, I would have had no idea what to search for.

    One last question, is a mosfet transistor limited to certain/maximum Amps?
     
  6. wayneh

    Expert

    Sep 9, 2010
    12,089
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    Yes, but you can get MOSFETs that can handle very high currents.
     
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  7. adam763

    Thread Starter New Member

    Feb 27, 2014
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    Thanks Wayneh.
     
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