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    Re: LED for Marine Sextant
    From: Doug Royer
    Date: 2006 Sep 8, 19:21 -0500

    You live around Nova Scotia don’t you? Go online and type in: http://www.newark.com

    Search for LEDs. I believe there is a $25.00 min order but you will be able to get ideas. I like the H.P. light bars as stated. They are rectangular LED packages.

    I have a Tamaya Spica and an Astra B-III and on both I disassembled the cover that holds the illumination for the micrometer and veneer on the arm. Snipped the bulbs out and placed 2 LEDs in parallel with each other (one facing the micrometer scale and one facing the veneer scale. Soldered the power leads to the corresponding leads on the LEDs. I used Dow Corning RTV 3145 to insulate the exposed leads and to anchor the LEDs into the proper position to illuminate the scales. Then reassembled the cover back onto the arm. Been using them at sea and on land for years with no problems. Battery life is also extended by installing LEDs.

    Good luck!

     

     


     

    Thanks Doug,

    A few more questions:

    Did you have re-configure the light bulb recepticle or were you able to obtain an LED that screwed into the existing recepticle.

    Can you recommend a particular supplier?  There are none anywhere in my particular part of the world.

     

    Robert

     


    > Robert,

    > Yes there are many types to be used. I've changed all my illumination
    > set-ups on each of my sextants to use LEDs.

    > Mail order houses/catalogs such as Newark, mouser, Digi-Key etc have
    > what you will need. In your town I'll wager there are surplus 
    > electronichouses that can give you what you need. 

    > On all my sextants the power for illumination is from a bank of 
    > two AA
    > batteries stacked in series in the handle.This will give you about 3
    > vdc. The LED should drop about 1.7 vdc of this across itself. 
    > Sometimesyou will need to add a current limiting resistor in 
    > series with the LED
    > to limit the current to about 20 m.a. At 3 vdc that will be about 75
    > ohms.

    > On mine I just didn't use the resistor because the light is not
    > activated for long periods of time and I've yet had one burn out.

    > I really like using the H.P. single element light bars in my set 
    > up. The
    > yellow wavelength lights I like the best. Red works but, for me, the
    > yellow is easier to see.


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