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About a Diy pc oscilloscope found on the Net

Discussion in 'Electronic Equipment' started by Gaetan Mailloux, May 2, 2007.

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  1. Hello

    I've found this pc oscilloscope web page;

    Any one try this ADC for pc scope ?

    Is there any freeware to do spectrum analysing (FFT) who would work with
    that PC parallel port ADC ?


    Gaetan, Canada
  2. scada

    scada Guest

    If you can save the wave with their software, you can do FFT with trial version is free, something like $35 to own it! I
    recommend it highly, I've been using it for years!
  3. scada

    scada Guest

    At a second look at that circuit, the A/D chip has only 8 bit resolution.
    That's not going to give you much of an FFT!

  4. Hello

    How much bit are need to do FFT ?


  5. scada

    scada Guest

    The Nyquest theory states you want to sample at a rate of at least twice the
    highest frequency you want to see.

  6. Hi

    Here's what they said at the scope web site;

    Key Features

    Sampling Rate 100K Samples per second
    -5 V To +5V Input Range
    -50V To +50V Olerload Protection
    8 Bit Resolution
    Scope Timebases:100uS/Div To 100mS/Div
    Scope Volts/Div: 100mV/Div To 5V/Div
    Works with ANY parallel port


  7. jcomeau_ictx

    jcomeau_ictx Guest

    So, a 50 KHz Nyquist frequency. A little better than twice what you
    get from the input port of your sound card, at much lower resolution
    (16 bits is 256 times the resolution of 8 bits, and 16 bit sound cards
    are commonplace). In Canada, as in the US, you ought to be able to
    find analog oscilloscopes for $50 or less at yard sales or eBay; that
    might be a better use of your money.

    I've used the input port of a sound card as a low-frequency digital
    scope. It worked, for example, to see the encoding on the magstripe of
    a credit card, by hooking up the read-head of an old tape player to
    the microphone port of my computer and dragging the card across it.
    This was years ago, and I had to write my own software. Nowadays you
    have freeware like Audacity that will do that part for you.

  8. Hello

    I mostly want to do spectrum analysing of distortion, I have a sine wave
    oscillator who have less than .0003 % distortions. Most soundcard do
    have quite high distortion to do that with a software, and buying a spectrum
    analyser adaptor for an oscilloscope cost quite to much for me.


  9. John Bordynuik cut and paste " I mostly want to do spectrum analysing of

    Hello Gaetan,

    Consider using fast ADCs (>20 Mhz ADS1610 or something), parallel
    interface or differential, then capture the data on the PC using an
    inexpensive (but fast) PCI DIO card. This solution would cost you less than
    $600.00 if you built it yourself.

    I just finished a 128-channel unit.


    John Bordynuik
    CPU Architect
  10. Jean-Yves

    Jean-Yves Guest

    I'm afraid you wont be able to detect such distortion with equipment
    that is less than $20000....
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