Vector Display Output on an Oscilliscope

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What can we say, we’re a sucker for projects featuring our logo. That being said, this one is seriously awesome. [CNLohr] has figured out how to create a vector display output on an oscilloscope… from a VGA port.

He was inspired by a game called Trace Vector, which is done in the same style as some of the old classics like Asteroids. This got [Charles] thinking, and he decided to see what it would take to make his own vector capable display. An oscilloscope is perfect for this, as it already works by controlling the position of the beam (like a vector), as opposed to standard LCDs and CRTs that use rasterizing (horizontal scanning). This means to get the oscilloscope to display a graphic, all you need to do is to vary the voltages going into the X and Y channels — well, at a high speed!

But where are you going to find such a high speed digital to analog converter? Oh yeah, your computer’s VGA port! For a few dollars [Charles] threw together a VGA adapter with a few resistors using just the red and blue outputs (source code). A bit of programming later, and he’s created his own vector display!

Stick around to see our lovely skull and cross-wrenches rotate on his oscilloscope! Oh, and for a more in depth explanation and more impressive vector video demonstration.

Comments

  1. ijg says:

    Only 30MHz?
    LOL, my Rigol does 100 megs with no problem.

  2. Luke Wren says:

    “Oscilloscope vector display”
    ehhh… not again…

    “uses the VGA port for its DAC output”

    Whoah! That is clever :L

    • Peter says:

      Agreed! With Most of the things I see on hackaday, I think to myself, “that’s interesting” or “that must have taken a lot of work.” It is not too often that I think, “wow, that was clever.” This is a clever hack.

  3. AndyT says:

    You need X, Y,and Z modulation to put that display up, not just X and Y as stated in your summary.

    Z inputs (brightness) are usually a BNC connector on the back of the scope for those who may not know.

    • VintagePC says:

      Aha! A use for that otherwise vestigial green VGA channel! ;)

      • RichC says:

        I wonder why he didn’t use red and green channels rather than red and blue. (Puny) human blue perception is relatively poor, sometimes video hardware takes advantage of that and renders it with fewer discrete levels (fewer bits).

        • Rich Grise says:

          It’s called “the blue channel” because it controls the “blue” gun of a color CRT o the one which is aimed at the blue phosphor dots. The electrionc signal has no color at all.

          • RichC says:

            On some hardware implementations, a video DAC has fewer bits assigned to it for the blue channel. For example if the RGB colour for a pixel is encoded with 16-bits then there may be 6 for red, 6 for green and 4 for blue. You won’t notice this when rendered to a colour because blue perception is poor, but when it is rendered to an horizontal or vertical offset it will manifest itself as poorer resolution.

    • CNLohr says:

      Indeed you do not! VGA is just /that/ fast. When you’re not in use or blanking, the beam goes back to the lower-left.

  4. Fredk says:

    Someone please make this work with MAME.

  5. Rich Grise says:

    How do you drive the DACs directly, and what do you do about sync? Doesn’t the VGA automatically do blanking? Or can the DACs be written to by output ports?

  6. OH – and here are some better pictures of the 10 year old version

    http://emergent.unpythonic.net/01115494353

    • CNLohr says:

      I am going to have to give some credit where credit is due!

      • RunnerPack says:

        If you didn’t know about his implementation, you deserve equal credit for independently coming up with this.

        Yes, it’s one of those “obvious, in hindsight” ideas, but you did it without the benefit of hindsight :)

        • CNLohr says:

          I actually googled for a few things to try to make sure no one else did it. Boy was I wrong.

          • Greenaum says:

            As they say, best way to get an answer on the Internet is not to ask the question. Just post an answer yourself and people queue up to correct you!

          • CNLohr,

            Good work non the less.

            It’s getting harder and harder to find anything with search engines. I’m obviously a fan of Asteroids and Tempest which is why I knew about the other one.

            Hell I am writing a version of Tempest for the Uzebox.

  7. RunnerPack says:

    I hope that old asteroids monitor I have kicking around still works. If it does, it’s definitely getting a VGA makeover!

    • echodelta says:

      I have one too. The bandwidth is somewhere under 1 MHz if I recall. It used magnetic deflection with current feedback.

      • Rich Grise says:

        I used to be a video game repairman, and those vector monitors are kewl! They’ve got a standalone PS for the anodes because there’s no flyback, and the yoke windings are one layer of about 12 turns of about #18 wire. Mr. Do! came out about two or three years after Pac-Man, but they offered a conversion kit – rather than spend $3,000 on a new game, they could gut an old obsolete one and install a new board and slap new skins on the cabinet for about $350, so they did a land-office business. I accumulated a lot of chips and stuff that way, because when you’d convert a game, the owner didn’t need his old board, so I salvaged a lot of them. I built my TV typewriter (like http://www.swtpc.com/mholley/RadioElectronics/TV_Typewriter.htm) with parts scrounged from old video games.

  8. Some Guy says:

    Oscilliscope? How about a hack to run all Hackaday submissions through a spell checker?

    • password says:

      i don’t understand the fuss about spelling

      • Rich Grise says:

        “i don’t understand the fuss about spelling”

        It’s about precision of communication affecting the perception of the quality of the information presented. I’m less likely to take seriously the opinions of someone who’s too lazy or arrogant to be bothered to check that they’re actually using the language properly.

        But hey, if you want to wave an “I’m an ignoramus” flag over your head, knock yourself out!

        • Rob says:

          I don’t like to be “that guy”, but poor spelling is a deal-breaker with me… And when I’m the one posting a comment and then realizing that I fudged up the spelling, it’s even worse. Oh, for an edit button on HAD comments!

          • password says:

            yes we are going to confuze a Oscilliscope with a Oscilloscope? I think more that people who focuss so much on other spelling , either does not care for the content , or does not comprehend it. Secondly , do you even understand how the brian process words , do yourself a favour and go to a reading instutute and let them test how you naturally focus on a word . People who read letter for letter tend to be reading ioncorectly

          • TheStarman says:

            Regarding all comments above having to do with SPELLING; e.g., what “password” said: It’s *not* a matter of whether us humans can figure out what someone means, because it’s quite easy from context and how we perceive words in context to often know exactly what they mean in spite of many errors. The problem with spelling is this: If you want someone to find your comments in a search engine and they don’t commit the same spelling error(s), they may never get a chance to see whatever information you provided that could have helped them. Google is getting better at ferreting out even our misspellings, but being accurate is the best way for others to find this info.

  9. TheStarman says:

    Many years ago (70’s and 80’s), I worked for a company called XYTRON; note the “X” and “Y” then tron (as in ‘electronics’). We made vector graphic monitors which were used not only by the Air Force in AWACS planes as well as other military displays of that era, but also in Hollywood. (It’s not much of a leap to wonder if the movie “Tron” was derived from our company name which was on front with the “X” and “Y” in silhouetted form and “TRON” in bold characters, when a producer happened to glance at the name while using our equipment.)

    The main point: Although we used varying size CRT displays; some of which were also used in color TVs, the units were basically oscilloscopes with very large X and Y amplifiers! The bigger the screen, the bigger the amps, which often used two big long finned heat sinks containing about 12 power transistors (one for each axis) and two very heavy transformers. Later we made a very small headset tube and towards the end, full color screen projectors (with red, green and blue projector tubes); which used very high voltages, requiring me to wear a radiation badge. We often tested the units using an old 68000-based mini-computer that created rotating graphic images of a fighter jet that could be manipulated by entering different values into the program.

    So, thank you for bringing back the memories!

    • TheStarman says:

      Wishing I could edit what I wrote about the name of the Tron movie. I just found out that they had already picked that name for the character/movie title years before anyone saw one of our monitors. But it’s still a cool coincidence that a company with the name XY_TRON contributed to its production.

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