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Good and large X-Y CRT?

Discussion in 'Electronic Design' started by Tim Shoppa, Oct 4, 2004.

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  1. Tim Shoppa

    Tim Shoppa Guest

    What oscilliscope-type CRT's are still being manufactured and
    widely available today? I need something with electrostatic
    deflection, and preferably with a big screen. Tektronix used to
    sell 8" or 10" square faced instruments which were perfect for this.
    I'd be satisfied with a bare tube, but would be happy if someone could
    point me towards a source of old Tektronix big-screen X-Y scopes.

    Looking around, I see that new 3RP1A's are being imported from China, otherwise
    all the scope tubes I see seem to be replacements for brand X model Y scope
    or pulls from old scopes. There seems to be a minor market in used
    ATC-style vectorscopes which are somehow magnetically deflected? Don't
    understand what's inside them and unless they're easily turned into X-Y
    instruments I don't care.

  2. John Larkin

    John Larkin Guest

    Used Tek X-Y boxes show up on ebay fairly often; I've bought a couple.
    But I've seen mostly smaller ones, not 8-10".

    What are you making? Could you fake it with a computer monitor and
    some ADCs?

  3. I may actually have a few "new" (meaning unused) round faced Tektronix ones in
    boxes in the garage. I could look. But not the square ones, if I recall.

  4. Julie

    Julie Guest

    I have no idea what your application is, but you can still get used X-Y
    monitors over in the vintage video arcade circles for under $500. If it can
    apply to you, go post in for further details.
  5. Dave VanHorn

    Dave VanHorn Guest

    I have no idea what your application is, but you can still get used X-Y
    I've yet to see a video game that ran electrostatic deflection.
  6. Rich Grise

    Rich Grise Guest

    I once worked with a unit that simulated sweep-scan on a raster display
    by adding a small coil on top of the vertical deflection coil, called
    the 'bend board'. They actually had a little circuit that, when you
    wanted to display a curved trace, you would write (80186 assembly)
    to the "bend register" and it would introduce a little bend into
    the trace, and literally smooth over the stairsteps. The segment
    of the next scan line would be bent a little to line up with the
    previous, and like that. It did look great, and some guy got a patent
    for the circuit. But it requires modifying the monitor, and I'm pretty
    sure there's a limit to how much "bend" can be applied, but it's a

    And it was incredible fun to code for. ;-)

  7. Rich Grise

    Rich Grise Guest

    What? You didn't do PONG on your scope when you were a kid?

  8. I read in that Tim Shoppa <[email protected]
  9. Tim Shoppa

    Tim Shoppa Guest

    I'm "just" looking at Lissajous figures in the few MHz region. If
    a video game monitor assembly uses a tube with magnetic deflection
    but makes it look like a good old X-Y CRT as far as what I have to
    feed into the assembly, then it'd work fine.

  10. Tim Shoppa

    Tim Shoppa Guest

    An analog computer that integrates the Lorentz equations while the user
    tweaks the knobs that vary the parameters. Part of a museum display on
    chaos and analog computing.
    In fact that's what I'm doing now:

    1. As fast as I can (inner loop),
    measure X and Y, go to that pixel and add, say, 100 units of brightness.
    If it would go over the max value (255 for 8-bit pixels) then just
    leave it at 255.

    2. Every sixtieth of a second, "age" all the pixels to simulate
    phosphor persistence by going over every pixel and multiplying
    its brightness by 0.95.

    Step 2 gives me a persistence of about a fifth of a second. A nice tweak
    is that I can change the aging rate to give me effectively variable
    persistence. While that's cute, it's not a necessity.

    But using a whole PC running full-throttle on this seems a bit of a
    waste, and defeats the simplicity of the analog multipliers and
    integrators used to solve the Lorentz equation. I was kind-of hoping
    to find a common X-Y CRT that will be available for a while into the
    future. I found the 3RP1A and was hoping to find something bigger.

  11. Rich Grise

    Rich Grise Guest

    Well, they're probably horrendously expensive these days unless you
    can find a video game collector - "Star Wars" and something like "Frenzy"
    or something, were vector displays. In fact, I think "Asteroids" was
    a vector display, monochrome.

    They have very sparse deflection coils, and mongo current drivers.
    Like, DC-100's KHz flat. But as long as it doesn't break, it's great!

    Good Luck!
  12. Julie

    Julie Guest

    Yes, EM deflection. The B&W units (Electrohome G05 series) come in 19" and 13"
    sizes, and are pretty much self-contained. You should be able to pick up a
    working used unit for around $250 or so.

    Theory of operation:
  13. Dave VanHorn

    Dave VanHorn Guest

    I've yet to see a video game that ran electrostatic deflection.
    Yes, but that's the other way around.
  14. Dave VanHorn

    Dave VanHorn Guest

    You won't find it in a magnetic deflection system.

    even the vector type games used magnetic deflection, and the specs just
    don't make it.
  15. John Larkin

    John Larkin Guest

    My favorite persistance algorithm is to, at some rate, just compute a
    random X-Y coordinate and zap that pixel. It makes a cool
    fading-scintillating effect, and uses very little compute power and no
    program memory. I could post an example (it would be an .exe file) to
    a.b.s.e. if anybody would like to see it. I think Tek uses this in
    their low-end digital scopes to fake persistance.

  16. Some of the low-end analog scopes use Hitachi flat-face rectangular
    tubes- not sure what size they go up to. If I was tasked with sourcing
    such a thing for small-scale production (no fun, I'm sure), I'd try to
    do it from Asia.

    Best regards,
    Spehro Pefhany
  17. The LBO9C Alignment Scope / X-Y Display Module is equipped with a
    9-inch screen. LB09C is made by Leader, not sure about the bandwidth,
    but was in production like 2-3 years ago. Same Leader that made the
    low cost chinese or taiwanese scopes.

    If you find some cheap, please let me know so I can mothball my Tek
    I actually used to do vector graphics for a living, doing laser shows,
    and still have the 5K worth of custom vector control stuff, including
    8 channel digital tape and a 68040 based PCI card that rides a PC bus
    to do the real time math. Of course nothing done for laser shows gets
    out of the high audio bandwidth, because of the mechanics of the
    galvanometer scanners, yet we can get 16 bit 3D wireframe with up to
    1200 points per frame, and still cram it into audio with almost no

    Steve Roberts
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