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Sharpening a squarewave

Discussion in 'Electronic Design' started by Mark Roberts, May 5, 2007.

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  1. Mark Roberts

    Mark Roberts Guest

    I am currently generating audio frequency squarewaves in the audio
    editing software "CoolEdit". Although there are others that will do
    the same job.

    However, I need something more harmonically pure for test purposes,
    ie. a squarewave that is perfectly rectalinear and has virtually
    instantaneous rise and fall times.

    It needs to deliver a 12V swing and hold up under a 16 Ohm
    non-reactive load.

    What type of circuit can I add to my soundcard output that will do
    this best?

    Mark Roberts
  2. Phil Allison

    Phil Allison Guest

    "Mark Roberts"

    ** You must come up with actual rise and fall time figures.

    If that doesn't strain your tiny brain too much.

    ** A power amp IC may be OK - depending on your rise and fall times.

    ** A "Schmidt trigger " will sharpen up the rise and fall times of your
    existing signals.

    However, you MUST come up with actual rise and fall time figures.

    Justify them too.

    All sounds like a giant wank, so far.

    ........ Phil
  3. Tim Williams

    Tim Williams Guest

    An XR2206 would do it.


  4. Eeyore

    Eeyore Guest

    Your sound card output is band limited for very good reasons. It won't make a
    truly sharp squarewave.

  5. DaveM

    DaveM Guest

    A harmonically pure square wave??? Now, how in the world is that possible??

    Dave M
    MasonDG44 at comcast dot net (Just substitute the appropriate characters in the

    Life is like a roll of toilet paper; the closer to the end, the faster it goes.
  6. Phil Allison

    Phil Allison Guest


    ** No harmonic missing - of course.

    Right out to fucking infinity ..........

    Beam me up Scotty .........................

    ....... Phil
  7. It's
    "Scotty, beam me up"

  8. John Fields

    John Fields Guest

  9. You mean like the second, the fourth, the sixth, and so on?

    The simplest way to get a square wave with very good symmetry is to us a
    binary divider.

    Many thanks,

    Don Lancaster voice phone: (928)428-4073
    Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
    rss: email:

    Please visit my GURU's LAIR web site at
  10. Fred Bloggs

    Fred Bloggs Guest

    Mark Roberts wrote:
    Rectal-in-ear huh? You must be British!
    View in a fixed-width font such as
  11. Phil Allison

    Phil Allison Guest

    "Don Lancaster"

    ** Why.

    Since their absence would be no surprise to anyone.

    Just like your brainless ASD fucked crap.

    **** head.

    ...... Phil
  12. MooseFET

    MooseFET Guest

    I am sort of surprised that nobody has already suggested this. If you
    have a comparitor to turn the sound card's output into sharper
    squarewave, you may still be off the 50-50 duty cycle mark. A good
    way to solve this is to use a flip-flop such as a 74HC74. This will
    give you a squarewave with the needed duty cycle but at 1/2 the
    frequency. Since the sound card can be programmed to make twice the
    frequency, you should be able to work with this.

    There still can be a bit of timing shutter on the output of the sound
    card. This is likely to go away when the cycle of the signal is an
    integer multiple of the sampling rate. Since this is true at many
    values you can just be selective in what frequencies you use.
  13. James Beck

    James Beck Guest

    Damn it Jim, I'm a doctor, not a breakfast cereal.....
  14. And then never actually used during the original series. "Scotty, beam
    me up" wasn't uttered until they put it in one of their movies.
  15. Rich Grise

    Rich Grise Guest

    I did hear, "Gentlemen, I suggest you beam me aboard" on the one with
    the neutronium doomsday machine.

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