Oscilloscope thinks it’s a video monitor

There is nothing wrong with your television set. Do not attempt to adjust the picture.

Where would we be if we listened to advice like that? [Eric] writes that with a fairly simple circuit, he’s able to split a composite video signal into its constituent X and Y ramp signals for display on his trusty Tektronix 465m. A LM1881 IC does the bulk of the heavy lifting. After running the signal through a few passive components, the generated ramp signals are ready for consumption by his venerable ‘scope. All that’s needed past that is some additional glue logic to invert the levels so the image shows up properly. The end result is a display that has an almost ethereal quality to it, like an old TV set or something out of the movie Brazil.

Hit the break to catch a video of the circuit in action.

Comments

  1. Pedro says:

    This is so awesome. I can’t think of a practical use (except for showing off to nerdy friends, I suppose) but I love it!

  2. wosser says:

    See also the “youscope” demo.

  3. No offense, but this is a standard project in many a college EE lab curriculum.

  4. austinmarton says:

    So awesome. Wasn’t in our curriculum unfortunately.

  5. strider_mt2k says:

    Cur-rick-cu-lum?

    I don’t know about all that, but that’s a damn fine lil’ hack right there.

  6. teqo says:

    I always thought the steampunquesque machines in Brazil where made of Apple IIc monitors, typewriters and Hollywood glue….

  7. Hirudinea says:

    Thats how they watched XHamster in the old days.

  8. Slanderer says:

    I mean, it’s hardly a hack in the sense that this is basically what the LM1881 was designed to do…

    I followed this years ago:

    http://www.electronixandmore.com/project/14.html

    And then added the additional inverter. Uses really common parts, and has a much cleaner scope output.

  9. Grod says:

    That was one of the projects we did in 2nd year engineering. That would have been about 22 years ago.

  10. Alan Parekh says:

    That looks creepy! That would be a great prank to play on someone.

  11. echodelta says:

    It’s even better when you set H or V to sub intervals, and mess with the aspect ratio like there’s no today on the tube. Come to think of it you can correct for the aspect ratio mess that has arisen since widescreen TV. Cool if you like black & green TV. Come to think of it most TV has turned a sickly green.

  12. Paul says:

    I vote for Youscope.
    For anyone who doesn’t know yet, Youscope is only a (stereo) audio file which is played on an analog (or really high end digital) oscilloscope. NO extra circuitry required.

  13. Dave says:

    Yes it’s a popular engineering lab experiment, but not everyone here is an engineer and it’s one of those things that is high payoff in cool factor for not much effort. You know- a hack.

    @Paul- never saw that before. It’s going on the scope in the lab this morning.

    http://blog.makezine.com/archive/2007/08/youscope-oscilloscope-dem.html

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