Bench equipment tip: Screenshot of old oscilloscopes

oscillocam-oscilloscope-camera-accessory

Here’s a quick tip on capturing the output of oscilloscopes that don’t have that native feature. [Paulo Renato] used a cookie tin as a camera cowl for capturing CRT oscilloscope screenshots.

We figure if you’ve got any kind of functioning oscilloscope you’re lucky. And although it’s nice to pull down the measurements to your PC on the newer models, the results [Paul] gets with this rig are still satisfactory. The plastic cookie box he used blocks out ambient light while holding the camera at a consistent focal length. He used some flat black spray paint to make sure the obnoxious yellow plastic didn’t interfere with the image, then drilled a hole which fits tightly around his camera lens.

You’ll need to monkey with the exposure settings to get the best image. But once you’ve got it dialed in it should be the same every time you want to take a picture of the screen.

Comments

  1. Ken says:

    This isn’t as daft as many people will think. Tektronix sold a polaroid camera specifically for this purpose back in the day.

  2. Tom the Brat says:

    Yup! Dad’s lab had one of those. Was attached to a hood. You could look into the hood to see the display, think “Mr. Spock,” and snap the picture.

  3. Alex says:

    Hilarious! At my college we had to do this with the spectrum analysers. Funny thing is, this was 2-3 years ago, and we used smart phones to do it. Too expensive to replace the equipment.

  4. Victor says:

    Just take a look at this picture:
    http://farm8.staticflickr.com/7045/6926143499_6a0241afb7_z.jpg

    It shows part of Jim Williams’ desk, with on the left a (Tektronix?) oscilloscope with an official camera ‘add-on’!

  5. sbrk says:

    If your old Tek ‘scope has RS-232 out, you can set the printer output to use that port and just capture it with a null-modem cable to another machine. Mine will even dump PCX (PC Paintbrush .. how’s that for ancient!) to this port.

  6. cyberteque says:

    I once bought an ancient ultra-sound machine the size of a large chest freezer, for $400, just for the polaroid camera…

  7. HC says:

    Why can’t you just turn the lights off?

  8. Joejoedancer says:

    How painful

  9. Z00111111 says:

    Could probably write up something in OpenCV to convert the image into computer useable data?

  10. Hoi says:

    The TDS model series pictured always have a GPIB port (some has RS-232 options, like TDS 544A). You can pick up a cheap RS-232USB converter for a little more than $100 in the used market and do way more with that than just taking screencaps :)

  11. djnikochan says:

    As someone whose only scope is a banged up, old, analog Telequipment D54, this trick could come in handy for me. I had seen scope cameras in the wild before, but didn’t realize they were just a hood and a conventional camera. Spiffy! Now if I could just get the old beast calibrated. A shop sticker on it says it was due for calibration December 1981; the month before I was born. Anybody got a hack for that?

    • Eatith Mee says:

      Yeah, Just rent a new scope that *IS* calibrated, run both of them off the same source and through a crap-ton of waveforms and amplitudes and compare, tweek your scope to match the calibrated one.

  12. Bob Fleece says:

    EG&G used this sort of thing during the era of nuclear weapons testing to capture the one shot waveforms that appeared for only a fraction of a second during a test. An LCD shutter was also developed. It had a much faster response time than a mechanical shutter.

    https://www.llnl.gov/str/June07/Bennett.html

    They even auctioned one of them off online recently. I assume TW stood for traveling wave as in traveling wave tube amplifier, something else EG&G developed in its quest for faster data acquisition.

    http://www.liveauctionworld.com/EG-G-850B-T-W-SCOPE-CAMERA-707-OSCILLOSCOPE-print-sequence-I511_i16783951

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