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Help. No idea what this is.

Discussion in 'General Electronics Discussion' started by KevinPhoenix, Oct 12, 2016.

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  1. KevinPhoenix


    Oct 12, 2016
    I picked this up at an Estate auction. I thought it was interesting. I have searched High and Low and can find nothing similar. It is made by the Rubicon Co. Philadelphia. A light bulb is located under the cylinder in the back corner. Any help would be greatly appreciated.

    Thx Kevin

    Attached Files:

  2. shrtrnd


    Jan 15, 2010
    The unit looked to me a lot like an old test and measurement standard. I just skimmed Google, and didn't
    see this exact unit, but saw articles that said Rubicon made a lot of resistance measurement standards like
    wheatstone bridges and such. If I had more time, I'd look some more.
    Try Googleing the Rubicon company, Radio Museum, things like that.
    Vintage sites.
    Last edited by a moderator: Oct 13, 2016
  3. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    Looks like a classroom moving-mirror galvanometer. The lamp housing in the upper right corner shines light onto the small square mirror which reflects the light onto the galvanometer mirror through the circular aperture (which may hold a lens). The light reflected from the mirror on the galvanometer is then directed toward the long mirror at the front of the box which then directs the galvanometer beam to an external screen after reflecting off the mirror in the cover of the box. Nice vintage toy. Great find!

    "Modern" versions of this type of moving-mirror galvo were cylindrical, about the size of the "lead" in a #2 pencil lead, and a couple inches long. Dozens of them were mounted side-by-side in a common magnetic field frame with coaxial electrical connections via a socket on the bottom. You could mechanically rotate each one to get the beam pointed in the right direction for recording on moving film. The deflected beams "wrote" traces on moving photographic film, often as part of an airborne data recording system, but also for laboratory use too. Frequency response extended into the low kilohertz range for the most expensive galvos, a few hundred hertz for the garden-variety ones. Thank heavens (not me) that digital took over in the 1950s and relegated multi-channel galvanometer recorders to the dust heap of history. Honeywell had a good run with them though for folks that needed the capability and were willing to spend big bux.

    They survive today in rugged, high speed (often mechanically resonant) form for use in deflecting beams of light from lasers for all sorts of purposes: laser light shows, laser engraving, laser scanning. and image-dissecting cameras.

    The first IR camera I ever encountered (a commercial unit available for sell to civilians) used a resonant horizontal scan to produce NTSC video, digitizing the output of two different liquid-nitrogen cooled IR sensors, storing each digitized line in a line buffer, and then playing it back twice with a DAC at the TV line rate, because the galvo wasn't fast enough to scan at the TV line rate. Plus, it was a sinusoidal scan because the mirror was driven at resonance. IIRC, an ADC provided spatially equal samples of the sinusoidal driving waveform and this was used to control the clock that performed the readout of the line buffer, yielding a substantially linear scan, spatially. Clever design I thought.

    My contribution was a high-speed analog switch that I added to the two video outputs to alternate between the two sensors every other scan line, thus allowing both IR bands (3 μm to 5 μm and 8 μm to 12 μm) to be displayed simultaneously on a single B&W TV monitor. The powers-that-be blanched when I suggested combining one of the two channels with a beam-splitter and a visible CCD camera synchronized to the IR camera to display visible imagery overlaid on the IR image.

    Apparently this had already been done for a classified project I wasn't "read in" to yet. Today anyone can do it, and combined with other sensors (such as synthetic aperture radar) the procedure is known as sensor fusion. It was hot stuff in the 1980s.

    A few years later we acquired a civilian hyper-spectral imaging system that used a holographic grating to direct a spectrally dispersed image from a push-broom airborne line sensor to 1024 detectors spanning the ultraviolet to infrared range, producing 1024 2D images recorded on 9-track digital tape. Each image represented a narrow slice of the electromagnetic spectrum. This wasn't "real time" though. It took many hours to post-process those data tapes into more images than the human mind is capable of perceiving in one fell swoop. Four-dimensional data: Each data set represented a 3D cube with two spatial axes and one spectral axis. And consecutive sets of data added a fourth dimension of time.

    So one of us (not me) sicced some spiffy computer programs on the data and finally got single frame images sorted by "false colors" into spectral bands that a human could interpret. Still not real time of course, but I suspect "some improvements" have been made since then. :D You could, for example, extract "signatures" from the data sets that would identify certain minerals or types of vegetation by their sunlight reflection properties. If you "false colored" the parts of the spectrum that matched the "signature", say with red, and displayed everything else in black-and-white then the thing you were looking for popped right out at you. The inventors of this contraption were trying to use it for airborne discovery of certain geological formations, but the military had much bigger expectations. Powerful enough processors didn't exist yet to massage all that data in real time. Much has improved since 1990 when I got out of that business.

    Moral of this story: don't discount technology just because it is old. Clean it up, add a little polish, and it's ready to serve again, although perhaps in ways not anticipated.

    The first time I saw a mirror galvanometer was in the 1960s in a Western Kentucky State College (it's a University now) physics laboratory. Their's was a ballistic galvanometer, sometimes called a string galvo, because it had little or no restoring force... no spring. That one was very sensitive and was suspended in a vertical enclosure vibration-isolated from the lab floor. I suspect your box contains a normal galvo with a restoring spring. It would be interesting to measure it's frequency response.
    Last edited: Oct 13, 2016
    Harald Kapp and bushtech like this.
  4. bushtech


    Sep 13, 2016
    Fascinating! Thanks hevans1944
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