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5v output from computer

Discussion in 'General Electronics' started by AM, Feb 22, 2004.

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  1. AM

    AM Guest


    I was attempting to get a 5V output from a computer and into a
    transistor to trigger an external circuit. Presently I am attempting
    to use the serial output but I just cant get it. Would really
    appreciate any advice.


  2. Robert Baer

    Robert Baer Guest

    There is very little power available at the serial port, it was not
    designed for powering anything.
    PS/2 and USB ports do have +5V power available; do not load more than
    You do not need any power (of merit) to trigger an external circuit,
    or to drive the base of a transistor; 10uA is more than enough for most
    devices and some will draw only a few microamps at most.
    You need to be mor eXplicit about what you are trying to do and how.
    For example, do you want to use an RS-232 output to turn something on
    and off?
    A CMOS gate has zero loading and might be part of a solution.
  3. AM

    AM Guest

    David & Robert,

    thank you for your reply.

    The link actually answers most of my questions.

    thank you

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