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PC based measurements

Discussion in 'Electronic Basics' started by Indroneel Ganguly, Jul 8, 2004.

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  1. Hello Everybody,
    I am trying to use my PC to measure resistance, capacitance and inductance
    of the
    respective components.
    I would like to use the parallel or serial port to do it.
    Do I need to have a ADC circuit to do it ?
    I would appreciate any advice on this.

    Thank you,
    Indroneel
     
  2. Yes, and a lot more hardware and software, including parallel port
    driver and a software packet to display/store thr results.
    I think you will be better off with a DVM with serial output and the
    related software.
     
  3. Yes, and a lot more hardware and software, including parallel port
    driver and a software packet to display/store thr results.
    I think you will be better off with a DVM with serial output and the
    related software.

    http://www.linuxtoys.org/dvm/dvm.html
    might get you started
     
  4. Don Taylor

    Don Taylor Guest

    I'm not usually happy when I say how I want to do something
    and people immediately respond by telling me to throw away
    everything I have and do it all differently, I'm really sorry,
    but ANY chance you might have a sound card you could use instead?

    If you put together a tiny oscillator with the frequency
    controlled in part by the component you want to measure,
    adjust the amplitude to be something the sound card likes.

    And then you could use available software to show the
    waveform, or software to measure the frequency, and from
    that calculate the value of your component.

    This might be easier than building an ADC or trying to get
    control of the pins on the printer port so you can measure
    pulse widths and/or frequencies.

    And if you really need to use one of the other ports then
    just ignore everything I said.
     
  5. If the OP had to ask this question then obviously he's got no chance
    of building his own serial/parallel port LCR meter!
    An off the shelf RS232 connected LCR meter (or similarly equiped
    multimeter) is the way to go.

    Dave :)
     
  6. Bob Masta

    Bob Masta Guest

    Yes, you need an ADC circuit, but it doesn't need to
    be a "conventional" one using a commercial ADC chip.
    If you are handy with programming low-level real-mode
    DOS, you can do all sorts of tricks based upon timing
    of printer port interrupt requests. You would need to
    convert your input variables to an appropriate period or
    frequency.

    You can make a simple 8-bit R-2R ladder DAC that
    the proper software can use to make a successive
    approximation ADC. The LPTX driver for my Daqarta
    software <www.daqarta.com/download> includes
    complete tutorial information on how to build this,
    which you can read on-line before you download.
    In many cases the whole works can be completely
    passive; nothing but resistors, while the PC does
    all the active stuff. If you use this circuit with the
    LPTX driver, Daqarta can read it as a waveform
    for a scope display, spectrum, or spectrogram in real-time.

    Finally, the simplest way to do many measurement
    tasks is to use the joystick port on a sound card.
    There have been many articles written on how to
    do this. The PC essentially measures resistance
    based upon how long it takes to charge up a
    capacitance as the resistance varies. You can
    thus measure capacitance by the reverse approach.

    Hope this helps!


    Bob Masta
    dqatechATdaqartaDOTcom

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    www.daqarta.com
     
  7. Thank you all for your replies.
    Using the sound card is something, I didnt know could be done.
    It looks most promising as an LCR is out of my budget and
    building a ADC is a more work.
    Time to read about what my sound card can do for me.
    Indroneel
     
  8. Try and google for the "parallel port faq" for how to interface circuits
    with the printer port. An interesting alternative on a PC is the game
    port, as it can measure resistance directly.

    Note however that direct access to the pp is possible only with DOS
    based operating systems, modern (?) Windozze versions require kernel
    modules. So it is probably easiest to recycle an old 386 or 486 for that
    type of experiments.
     
  9. Tim Auton

    Tim Auton Guest

    Easier and less expensive if you happen to do something wrong! Unless
    you're already familiar with Windows development I'd go for Linux or
    one of the BSDs - plenty of good, free development tools for more
    languages than you can shake a stick at.


    Tim
     
  10. Guest

    Look for "io.dll" in google, it is a free 'dll' file from which you can call routines
    to access the Parallel Port. With some tricky programming it works in all versions
    of Windows.
    I have just purchased PureBasic (59 Euros) which works in windows, creates full 32 bit
    applications, has a wysiwyg interface generator so you can create nice standard
    'Windows' in minutes, and this connects to the Parallel Port via "io.dll" easily.
    I am a novice programmer, only learning enough to get done what I need, and I
    created a simple application that drove my P.Port interface in the first couple of days.
    Regards, KT
     
  11. Rich Grise

    Rich Grise Guest

    Of course, when you install Linux, you can do anything you want to do
    to anything in/on the machine.
     
  12.  
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