Build an Oscilloscope

Discussion in 'The Projects Forum' started by Ghyrt, Jun 15, 2009.

  1. Ghyrt

    Thread Starter Member

    Jun 3, 2009
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    Hi, I was looking into getting an inexpensive oscilloscope and decided I wasn't willing to spend the money right now. Is it possible to make something like the ProbeScope for cheap? My idea was to use a serial microphone port. Assuming one has the programming ability, is this possible? I don't need to get numerical data, I'd just like to be able to observe the behavior of circuits I build. Any input would be appreciated. Thank you.
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,764
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    Ever hear of using your PC sound card to make your PC into a low end Oscope?
     
  3. Ghyrt

    Thread Starter Member

    Jun 3, 2009
    10
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    No, I haven't. How would I learn how to do that?
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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  5. Ghyrt

    Thread Starter Member

    Jun 3, 2009
    10
    0
    I found a free program. It seems to be what I need, but I'm not getting a reading from my circuit. I built a voltage divider with a 1 MΩ and 100kΩ resistor. The voltage drop across the 100kΩ resistor is about 1V (which is supposed to be safe for the computer). Any idea why there is no visible change in the oscilloscope?
     
  6. jut

    Senior Member

    Aug 25, 2007
    224
    2
    Sound cards remove the DC component of a signal. Check out my post from last week:

    http://forum.allaboutcircuits.com/showthread.php?t=24455

    The input is really a square wave, but as you can see in the first screen shot of my post, the scope shows the voltage fading back to zero because the sound card is "taking out" the DC.

    Try building a 555 timer circuit to output a square wave and feed it into your sound card scope.
     
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