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Drawing Power from an RS232 Port

Discussion in 'Beginner Electronics' started by S. Ethier, Apr 11, 2005.

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  1. S. Ethier

    S. Ethier Guest

    I am interested in drawing power from an RS232 port so that it powers an
    external circuit, only I am not too sure where to begin. The RS232 port
    is not on the DTE side, but on the DCE side. I was able to measure
    -7.59V DC and -25mA on the following PINs using a digital multimeter:
    RI, DSR, DCD, CTS.

    Is it possible to draw power from this DCE so that I have +3.3V DC at
    approximately 140mA for my circuit? Let me know what you guys think.

  2. Kevin R

    Kevin R Guest

    There's no way you're going to get 140mA from a serial port,
    not at 3.3 volts anyway.

    How about USB instead ?
  3. No, there's not that much power available. Not even from all the signal
    lines combined.

    John Musselman
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