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Thread: Back then...this is what we did...

  1. #1
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    Unhappy Back then...this is what we did...

    In this thread I will post things that show what I (or others, feel free to join in on this post) came up with when starting out on the amazing enterprise and journey of becoming a laserist, building projectors and control consoles and special effects for pleasuring the eyes and ears of our patrons. For me the journey began when I was working as a theater union projectionist, having previously worked as an audio recording engineer. After a few years absence from my first two years of college I took some class at a new local junior college taking astronomy, geology, anthropology, calculus, trig, ac/dc electronics and other things. I was taken back, blown away, that the astronomy classes were taught in a 40 ft. planetarium dome with a Spitz 512 star projector and was equipment with a fast array of other visual special effects projectors and 35mm slide projectors, planetary orrery, etc. It wasn't long that I volunteered to help with producing audio taps used in multitudes of astronomy related planetarium shows for the public. During my 2 or 3 year of being a volunteer planetarium nerd and having audio/electronic and optical skills the planetarium director urged me to build a laser projector like Laserium. After a brief education on what all that entailed I jumped in with all feet. I had the opportunity to create laser shows at this facility and make money in the process. The college and I came to a business agreement to split the proceeds by selling laser show tickets to the public. After quite a few months, I put together a simple business plan, showing expenses and cash flow and presented it to my local bank to get a short term loan, which I believe was for $8,000. That was enough money to do a lease/purchase with Coherent Radiation for a 1W mixed-gas krypton/argon ion laser, purchase eight GS G-115 open-loop scanners from General Scanning with front surface mirrors and mirror mounts, (I couldn't afford to buy their scanner drivers or scanner mounts and built my own. More on that later.) The rest of the money went for IC chips, sockets and other electrical components for building the myriad of circuit boards for building a phase-lock loop/free running set of sine, triangle and square wave generators along with amplitude modulation oscillators and other good stuff. My primary shop tools to make many of these things were a Craftsman table saw and drill press. I cut slots in aluminum panels for slide controls on my table saw.

    My projector was going to consist of RYGB scan colors from four sets of XY scanners plus RYGB special effect "clouds". I mentioned in another recent Lumia post that back then we called them laser clouds, regardless of the type of cloud that resulted from the "effect" of the distortion material. For creating Lissajous patterns of many forms and variations the console had four PLL oscillators that could be phase locked or in free run mode that generated sine, triangle or square wave patterns from a base frequency of 45 Hz to 450 Hz, select-able in harmonics 1 through 10 of 45Hz. (in free run mode the high end frequency was slightly higher.) There were two independent PLL oscillators one pair for X and the other pair for axis outputs. Each oscillator output magnitude was independently controlled by an audio taper slide potentiometer. PLL outputs 1 and 4 created an XY pair and 2 and 3 created a 2nd XY pair and could be individual set for a phase-locked harmonic from 1 to 10 and then summed together via slide potentiometers, (Ch.1 + Ch.2 for X's output and Ch.3 + Ch.4 for Y's output). The was a phase control knob that could set the phase-locked phase difference between the X and Y channel outputs. The sum of the four PLLs were sent to each of the four XY scan drive amp pairs. In addition, each PLL and/or free run oscillator could be switch selected to be amplitude modulated by one sine, square oscillator, while a second oscillator could be used only for CH.3 and Ch.4's outputs.


    This first photo is the finished result of my 1st generation PLL console.
    Click image for larger version. 

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    The 2nd photo shows how it eventually evolved. To the right is my old Heathkit dual-trace scope I used for an XY output preset monitor. The toggle swiches above the console were the ON/OFF flags for the 4 scanner beams and 4 cloud beams, plus ON/OFF switches to control relays that turned Synchron motors on or off (that drove the cloud disks.) (edited 12/01/2020 - change could beams to cloud beams)

    Click image for larger version. 

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    The console case was recycled by me from a DIY 2 channel, low impedance microphone mixer my dad built years earlier.

    In 1979 I added additional XY image source switch to allow the Apple II's AppleDAC outputs to be selected on XY1 or XY2 channels.

    These next photos are is the 3rd generation of this same basic console.

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    This photo shows how wire-wrap methodology helped compact the circuitry. There was no way I could afford to have PC boards made back then but eventually I did.
    Click image for larger version. 

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    So, by this time my principal image sources were from the 4 channel PLL outputs and the Apple IIe's AppleDAC. Also, the version 3 console had digital blanking oscillators that were used in conjunction with the Apple's image blanking and IntraActions Acouto-Optic modulators, one for each of the four colors.

    Next, I will show images of my very first method for blanking the image beams with a spinning cardboard blade (only one every got partial burned by the 1W beam) placed on a lead screw in the beam path right where it exists the laser....AND.... DIY scanner mounts, from my 1st ones to the last variations of my quad XY, RYGB high density mounts for GS G-120PD scanners, still using the krypton/argon 1W mixed gas ion laser or the krypton only variant. You guessed it, all but my latest, greatest scanner mounts were made with 3/8" aluminum 6061 bar or plate, a table saw and drill press, and thread taps.

    The saying, "necessity is the mother of invention" holds true and I hope those laser enthusiasts among you will take inspiration from these and the posts on this forum.
    Last edited by lasermaster1977; 12-01-2020 at 12:17.
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  2. #2
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    I will read later when I am done with work (I came for the pictures!). My initial TL,DR response: Wire wrapped...

    Click image for larger version. 

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    Those who fail to grasp art are the ones who criticize it.

  3. #3
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    Quote Originally Posted by absolom7691 View Post
    I will read later when I am done with work (I came for the pictures!). My initial TL,DR response: Wire wrapped...

    Click image for larger version. 

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    Aw, now...I had to Google "TL,DR"

    ...and before there was wirewrap there was adhesive copper tape.
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  4. #4
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    Wow I didnít know the xr2206 was that old.

  5. #5
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    Most of the boards in a Laserium projector other than the scan amps were wire wrapped.
    Eventually this had a printed circuit board done, but I saw several wire wrapped models:

    Click image for larger version. 

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    [QUOTE=absolom7691;353149]I will read later when I am done with work (I came for the pictures!). My initial TL,DR response: Wire wrapped...
    "There are painters who transform the sun into a yellow spot, but there are others who, with the help of their art and their intelligence, transform a yellow spot into the sun." Pablo Picasso

  6. #6
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    Quote Originally Posted by laserist View Post
    Most of the boards in a Laserium projector other than the scan amps were wire wrapped.
    I saw a few wire wrapped boards at MWK when I worked there. Amazing workmanship. I can't even imagine the patience and precision associated with the craft and then ramp that up to projection consoles.
    Those who fail to grasp art are the ones who criticize it.

  7. #7
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    Quote Originally Posted by absolom7691 View Post
    I saw a few wire wrapped boards at MWK when I worked there. Amazing workmanship. I can't even imagine the patience and precision associated with the craft and then ramp that up to projection consoles.
    Actually it is far easier than you may think, but there are two types of wire-wrap tools. One, you slip over the wire-wrap post and twirl with you fingers for 6-7 wraps and accepts small diameter wire spool bobbins. This is the poor mans tool. The more preferred is the electric motor driven version that allows you to set how many wraps it is to make when the trigger is pulled and accepts much larger wire spool bobbins. I'll post examples of these if requested.

    Here is an example of one of the boards from my final control console, named Lasermaster and made with the electric wire-wrap tool.

    Click image for larger version. 

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  8. #8
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    Default Very Cool

    Alden,

    Thank you for making this interesting and informative thread. I really enjoyed reading about and seeing pictures of the First iterations and what a difference between then and now. Looking forward to more pictures and continuation.

    And be careful.

  9. #9
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    Quote Originally Posted by icecruncher View Post
    Alden,

    Thank you for making this interesting and informative thread. I really enjoyed reading about and seeing pictures of the First iterations and what a difference between then and now. Looking forward to more pictures and continuation.

    And be careful.
    Thanks, icecruncher.

    As indicated earlier in this thread, here is what is "almost" the most crude means of beam blanking that I first made, after using my first control console for 3 or 6 months doing planetarium laser shows (I've slept since then and don't recall exactly) Here is the verbal description followed by photos, including a CAD "construction" showing all lines drawn for a blade before cutting it out.

    7-inch Diameter Cardboard Chopper Wheel: created 1978-79 and used in planetarium laser shows for years
    Unfortunately no photos of the "chopper box" survived, so I will endeavor to document it with modern drawing means...and words. ;-)
    Dense, sheet cardboard was used for this chopper wheel that is .045" thick. I have no recollection of where I got the cardboard from that long ago, but I can say with
    confidence that today, one could take two thicknesses of a Coors Light 12 or 24 12 oz. can cardboard container, glue them together appripriately and will yield very close to this thickness.
    That is to say, the cardboard density was similar to twice the thickness of today's Coors can container box. It is quite likely that the cardboard I used was what was referred to as
    "shirt cardboard". Back then, if shirts were sent to the Cleaners, er ah, clothes cleaners, they came back washed, possibly starched to some degree, ironed and folded neatly,
    with a flat piece of cardboard used to fold the body of the shirt around so the shirt stayed "nicely formed, neck and collar centered on the rectangle of the piece of cardboard".

    I used two chopper wheels in my first beam chopper solution. I made an 18 and 36 tooth chopper wheel out of .045" thick cardboard, each with a 7" diameter, using only a
    pencil, draftsman circle compass, 180 deg. draftsman's angle protractor, a steel straight edge ruler and a pair of sharp scissors.

    Here is how the cardboard chopper blades were constructed.
    A center point for each circle was marked on the cardboard with the circle compass and a 7" diameter circle drawn. Then, using the angle protractor centered on the center point, radial
    marks were made on the 7" diameter circle's circumference at either 5 or 10 degree intervals. (5 degrees for a 36 tooth blade and 10 for a 18 tooth blade.) Diameter lines were then drawn from each
    radial degree mark through the circle's center point to the opposite side of the circle. See diagrams provided.

    A 6" circle was then drawn by the circle compass centered on the 7" circle. This defined the length (or depth) of each blade tooth at 1.0". As I going through the process of "drawing"
    out the chopper blade format, I began to realize it would be possible to give each blade a sloping trailing edge, while the leading edge was a radial line, thereby providing a pulse-width modulation blanking effect that would range between 50% ON/OFF to 0% OFF, depending on how deep the beam was into the blade's teeth. All I had to do was be reasonably accurate and consistent with cutting the profile of each blade on the chopper wheel.

    This is THE original 36 tooth blade. It survived!!
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    The 1W beam diameter at the ion laser's front aperture was close to 2mm or .08", so the caliper is demonstrating the beam diameter at that point in the blade opening.
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    This drawing demonstrates the construction lines and where scissor cuts were made in the cardboard, also note the 2mm diameter circle at 12 o'clock in between two blades.
    Click image for larger version. 

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    Once the blades were finished they were sprayed with flat-black enamel spray paint and mounted with hot glue on a 12vdc motor's brass, flat pulley face.

    Small 12vdc motors with small, 3/8" diameter brass pulley hubs, were used to spin and the cardboard chopper wheels affixed with, what else? HOT GLUE.
    The dc motors where mounted on a Teflon v-notched block, roughly 1" x 1" x 2" . The Teflon block had a lateral hole drilled through it's base to accept a small 12" long, 3/16"
    diameter lead screw with just enough friction for it to move back and forth on the lead screw. The lead screw was supported at each end and gear driven by another 12vdc motor.
    Each chopper wheel's dc motor was driven by a 1 amp current-limiting, op amp whose output voltage was set by a 10-turn rotary potentiometer on the control console. This provided
    a simple, surprisingly stable means for controlling the chopper's rotation rate.

    The two horizontally mounted lead screw mechanisms with their two chopper wheels were enclosed in a 3/4" thick, particle board box, painted inside and out with flat black Krylon paint, that was roughly 14" long, 8" deep and 8" tall. The front and rear faces of the container box had a 2" diameter hole drilled that allowed the laser's output beam to pass directly through the box. The chopper blades would be "queued up" to be just out of the laser's beam path through the box, at one end of the box. The two drive amps and power supply were mounted on top
    of the chopper enclosure. This enclosure was placed on the same wooden platform that the ion laser was sitting on. See drawing.

    When the horizontally oriented lead screw was energized it would move the Teflon block with chopper motor (and wheel) back and forth into and out of the 1W laser beam. Moving the
    chopper blade further into the beam changed the on/off duty cycle and shortened the "On" length of any scanned line in an image provided the frequency of the chopper blade's ON/OFF
    cycle was a higher harmonic multiple of the scanned Lissajous pattern or image.

    I think in 4 years of use, only one chopper blade caught fire (partially) when it was moved into the 1W beam path without it spinning. Then we eventually changed to acousto-optic-modulators!

    More to come. (not sure why this image below is showing ??)
    Last edited by lasermaster1977; 06-06-2020 at 17:53.
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  10. #10
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    Great thread. I saw laserium in 1975 as a 9 year old in cleveland. Iím still here. Few move moving experiences in my life.

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