anyone know anything about optical comparators? - Page 3
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  1. #41
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    Default Kodak comparator.

    Most of the fans in these older units are locked up from dried lubrication. The lenses get hot and crack. The squirrel cage fan is underneath the unit and is a pain to get to but easy to fix. I rebuilt one of these for a friend a while back and I have to say Kodak (Optical Gaging Products) made a very nice comparator.
    Charles

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  3. #42
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    Yes the fan for the surface projection bulb would not start due to dried up lubricant in the bearings. The bearings were also some very obscure size. I pulled a shield and regreased them and it all works as it should. Was a bastard to get to the fan. No damage to anything in that area from the non working fan. That fan had only stopped working in recent times. Big capacity 1000W bulb in there though.

    Being doing lots of research on the internet. What I have found out.

    The only light beam that can be properly collimated is laser light. Reason being for other light sources the single point light source is but a theoretical creation, much like a single point. Bulbs like LED's are not single point light sources.

    Out of the blue I managed to pick up some comparator parts on ebay. Not for a Kodak, but a 14" Mitutoyo. Goodies included a brand new 14" glass screen and accompanying holder. A red and green filter lenses, and some other less relevant stuff.

    I tried contacting CCP a company whose manager used to post on here saying to contact them for any help on these older units. Kodak Optical Comparator help needed Got nothing back from them, they must be very busy.

    The various lenses I bought from Surplus Shed have arrived and one of them seems to be the one to use, to replace the broken one.

    I also ordered a couple of aspheric lenses, to see what they will do.

    Still waiting on the driver for the LED to arrive. USPS is much faster then china post.

    With new methods of manufacturing and LED lights there has been some new Lens designs out there. https://www.auer-lighting.com/filead...b487355afd.png Some do not look anything like a lens. The other thing is the complete misuse of the word "collimated" with regard to light. Advertisers are selling what they call "collimating lenses" with a choice of lens spreads, and by spreads I mean tens of degrees, rather then sub one degree.

  4. #43
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    Got the LED driver today, had a play this evening. Looks like just under 2000 lumens will be ample light. The screen lit up like never before.

    Also thought while the big 1000W surface projector bulbs are still available at a reasonable price, I picked up three of them at $12 each.

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  6. #44
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    Well I have blown the driver up.

    Note to self and anyone else powering a high powered LED.

    LED drivers made for torches get amazingly hot and cook themselves when powered by 12V DC, even though they are supposed to handle it.

    I have since found out these drivers are made small to fit in torch bodies and a forum of torch enthusiasts is probably not the best place to get advice for LED's being used for a different application.

    I have now come across these devices.

    DC 3W 2A CC CV Constant Current Adjustable Converter Step-Down Voltage Buck | eBay

    Being CC and adjustable both current and voltage output and of a high power capability (I only need less then 30W output) it should be the ticket. Downside is the three weeks to a month for it to arrive.

    High Power LED Tutorial #1 - How to Drive 1W and 3W LEDs from 12 Volts - YouTube
    Last edited by RC99; 09-07-2017 at 02:18 AM.

  7. #45
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    Quote Originally Posted by RC99 View Post
    LED drivers made for torches get amazingly hot and cook themselves when powered by 12V DC, even though they are supposed to handle it.
    Not having seen the specs I can't dispute that.

    But 12 volts is awfully high voltage for a flashlight (torch).

    I would expect no more than 6 batteries (9 volts) in the largest.
    Four batteries (6 volts) or fewer are much more common.

    - Leigh

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    So light was great, screen looked better than anything...but it died in hours?
    Keep us updated.
    Bob

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    In the context of a comparator that previously used a high-wattage incandescent source for illumination, the 3W LED heat output is almost inconsequential from the system perspective, but it is critical to get the heat away from the LED junction for continued survival. In designing and engineering instruments using LED sources, we pay a lot of attention to heatsinking the LEDs.

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  11. #48
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    Quote Originally Posted by CarbideBob View Post
    So light was great, screen looked better than anything...but it died in hours?
    Keep us updated.
    Bob
    Yes light was great in the bodged up trial, but the driver has burnt out. I bought the wrong type of driver.

    I also will be improving air flow within the lamphouse. Pictures with be forthcoming when I get something substantial done.

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    Well some advancement and another setback. For some reason my expensive LED has died. Gives you the shits when this sort of thing happens. Especially when I have designed a holder and printed it in plastic as a proof of concept. I am not going to replace the LED I had but rather move on to the now available Luxeon V led which is now on the market and has been trialed by someone and the results documented Lumileds Luxeon V, test of a 4K 7CRI emitter | BudgetLightForum.com These LEDS are about $4 each bare, hopefully soon some will be available attached to boards. In the meantime I am going to try a cheap CREE LED.

    The holder I made required no modifications for the projector. I did pull out the fan for this light and found the blades were covered in dirt and gunk. Cleaned up and it blows more air then ever before.

    20170917_171420.jpg 20170917_171409.jpg 20170917_171212.jpg

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    Just to make sure we are working on the same page... 20X and 14" screen machine is the desired package?
    Bob

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    Yes, 10X or 20X. That is all I have fitted to the carousel. Generally 10X is ample. 14" screen

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    Quote Originally Posted by RC99 View Post
    Especially when I have designed a holder and printed it in plastic as a proof of concept.
    I'm missing something here.

    The photos show a very large heatsink attached to the plastic holder. For what purpose? It won't do anything.

    In the first photo there's a black shroud surrounding the heatsink and the rest of the assembly. This would kill the heatsink function. A heatsink requires free air circulation.

    And for it to work, it must be attached to a metal assembly, not plastic. There must be thermal conductivity between the heat source and the heatsink. If you tried to run your expensive LED with this configuration, that would explain its failure.

    - Leigh

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    Quite right you are missing something.

    The LED module gets attached to the heatsink. There is a fan in the bottom of the lamp house that directs air up through that black shroud then it goes back down the outside of the shroud to exit the lamphouse.

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    If you want to the maximum useful life out of high intensity leds, use a pwm (pulse width modulation) controller.

    BTW, this is not a typical dating site.

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    It will not see massive amounts of use and my testing seems to indicate I need no where near as much light as I was expecting.

    While waiting for my new LED's to arrive (order got stuffed up so will now be next week) I remembered I had a LED light bought years ago. No idea of how many watts. Would only be 1 or 3 or so I guess. it is a 20mm PCB though.

    This was the result of a helical tap.

    20170921_210003.jpg

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  21. #56
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    For giggles I bought an aspherical lens. ~$5 delivered from China. It is supposed to be for LED torch use, and is to help stop aberations. Runtime Error

    Initial tests just holding the lens in place by hand seem to indicate that using it alone is going to be better then using the existing lens system. Going to print up a holder for it and see how it goes. Have to make a MkII holder for the LED as well. It needs some minor changes.

  22. #57
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    I have some litle things to do, but looks like I am on a winner.
    I now have a CREE XHP35 LED running at 1.1 amps with an output of 13W or so.

    The whole screen lights up quite well.

    The LED holder is at the Mk3 stage and I am pretty much finalised on this design. I need to work out why the fan circulation is so crap. I think it needs holes up the top of the lamp house so the air flows through. The LED does get warm, as it is being slightly overdriven. I will also need a better power supply for the LED. I only have 12V and need 13+V.

    So anyone else wanting to retrofit I used a cheap 50mm aspherical lens from Deal Extreme. A CREE XHP35 (although I may yet put a Luminleds Luxeon V in when they become more readily available) and a suitable driver.

    I did blow some $ on the original LED and driver, but that is what R&D is good at doing.

    Surface illumination works well as well.

    20170927_120502.jpg 20170927_115957.jpg 20170927_120803.jpg

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  24. #58
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    Carbide Bob made reference to using printed out transparencies on the screen.

    Volia. 2017-10-03_17-29-17_hdr.jpg

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