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basic question

Discussion in 'Electronic Basics' started by Mike_in_SD, Feb 13, 2007.

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  1. Mike_in_SD

    Mike_in_SD Guest

    the speed sendor/sensor on my streetrod transmission turns on and off
    (pulses) 12v sending it to the speedometer.

    I have an old scope that I barely know how to use .. and it shows
    a nice square wave

    with the speedo disconnected my fluke reads 6v
    so I guess I am measuring average voltage.

    now the problem

    Im working on a project where I feed these pulses to a microprocessor

    If I dont have the speedo connected and just connect the sender
    to the micro .. it works fine.

    but ..

    when I connect the speedo and "tap" into the signal line
    I only measure 1v and its not enough to trigger the micro

    not sure what to do ..

    thanks for any help
  2. ehsjr

    ehsjr Guest


  3. Bob Masta

    Bob Masta Guest

    CMOS buffer would be easier and better for square waves.
    The ever-popular CD4049 has 6 in one package. These are
    inverting buffers, so if polarity is important (which I doubt here),
    use one of them to invert the sensor signal, and feed it to
    the rest, which invert it back. You'll then have 5 copies of the
    signal to use. You can parallel these as needed if one
    destination needs more drive current.

    Best regards.

    Bob Masta

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    Scope, Spectrum, Spectrogram, Signal Generator
    Science with your sound card!
  4. Mike_in_SD

    Mike_in_SD Guest

    (Bob Masta) wrote in <45d1c06f.2054715>:

    Cool Bob .. I'll check that out .. thanks

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