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Thread: Retro fitting an LED to an old 2D flashligh

  1. #1

    Default Retro fitting an LED to an old 2D flashligh

    Good morning, I have purchased an LED, driver and lens from ebay
    http://www.ebay.com/itm/NEW-Cree-XHP...38.m2548.l4275

    however, the seller is unable to furnish me with a schematic of the driver.

    I am trying to retrofit this LED into an Ray-O-Vac Sportsman flashlight to have some style with the efficiency of an LED. I selected the 5K LED, and the 25° Lens.

    I am interested in confirming if the upper range of the voltage input and what the efficiency might be as the batteries are run down.

    I would also like to ask for suggestions on how to heatsink the LED in the old style body. I was thinking of going on the lathe and turning down a piece of Aluminum, but I am not sure how to follow the contour of the bell end.

    Is there an easier way to get some heatsink behind the LED and into the body of the flashlight?
    I am still on the fence on weather to use the original reflector and machine off the back where the incandescent bulb went in or use the lens that came with the LED. I was presuming to machine off a 1/4"" to get the LED up to about the filament level since I assume the reflector curve is based on that focal point.

    thank you for your time and have a good day

  2. #2
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    archimedes's Avatar
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    Default Re: Retro fitting an LED to an old 2D flashligh

    Your post above has been approved, but the thread has been moved to the "Homemade / Modified" subforum
    ... is the archimedes peak

  3. #3

    Default Re: Retro fitting an LED to an old 2D flashligh

    With the forward voltage of that driver being 6v or less, that means you can really only run one 26650 Lithium Ion cell (4.2v) or two D cells (3v). I'm assuming your host only holds two D batteries. The LiIon cell would certainly have the juice to pump out 2,500 lumens, but two alkaline will certainly not, for any length of time.
    The second issue is that you will have a great deal of heat to pull away from the LED emitter. What are you thinking in terms of heat sinking? Generally speaking, upgrading an old incan C/D cell host means machining up a pill to house the LED board and driver.

    You can look up Adventure Sport Flashlights on the web (username of vesture of blood on these pages), he sells some interesting upgrades for maglites, it will give you an idea of what is necessary, and what is possible.

    Once you get your post count up (3 or more, I believe), you can post some photos of your torch. Do you have the ability to machine/ lathe parts? What is your comfort level on working with soldering electronics?

    ~D
    Have torch, will travel.

  4. #4

    Default Re: Retro fitting an LED to an old 2D flashligh

    I did want to see if there was a typical schematic that was used for these flashlight drivers so I could try to understand the topology, I am evaluating if a de-coupling capacitor across the batteries would buffer high switching currents to improve performance.

    My other question is about heatsinking options, and any unique approaches people have used.
    I may turn a slug around 34.5mm diameter and use an expoxy filled with metal filings to bridge the gap between the slug and where the bell flares out for the reflector.
    I will look for the maglight retrofit kits that you mentioned. I think I saw something like this on Youtube. It looked like they used 3 XHP50s on an aluminum heat sink. However in that video the person then set a crumpled newspaper piece on fire.
    I am not sure if that demonstration was to be taken as a positive or as a warning of the danger that retrofit kit had.

    Thank you again, and if anyone has some good suggestions on epoxies with good thermal conductance that would be appreciated.
    Last edited by archimedes; 08-11-2017 at 01:45 PM. Reason: fixed quote tags

  5. #5

    Default Re: Retro fitting an LED to an old 2D flashligh

    Has anyone ever tried this
    http://www.overclockers.com/need-the...make-your-own/

    it looks like instead of metal fillings from the lathe they are using thermal paste.

    Also, another thought, has anyone used the clear acrylic hobby material to fill in the lit side of an LED to allow heat to flow foward as well?

    thank you and have a great Saturday.

  6. #6

    Default Re: Retro fitting an LED to an old 2D flashligh

    I just use two-part thermal adhesive, I think mine is from Thermaltake. You can get the fancy stuff with the silver in it, but the main thing is to just make a thermal pathway between the LED's board (MPCB) and the pill.

    I've used clear epoxy that included some glow powder a couple times, just for fun. I doubt it helps with drawing thermal energy away, but it looks cool
    Have torch, will travel.

  7. #7

    Default Re: Retro fitting an LED to an old 2D flashligh

    Thank you Dan, do you happen to know what the setup time is for your expoxy?
    I prefer a longer set up time so I don't feel as rushed. I can let my flashlight sit until the next day for it to set.

  8. #8
    Flashaholic* kosPap's Avatar
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    Default Re: Retro fitting an LED to an old 2D flashligh

    Quote Originally Posted by madbadgers View Post
    I did want to see if there was a typical schematic that was used for these flashlight drivers so I could try to understand the topology, I am evaluating if a de-coupling capacitor across the batteries would buffer high switching currents to improve performance.
    I think most buffers do soemthing liek this. They have a capacitor at the exit towards the LED to even out voltage fluctuations.
    I do nto see a reason to try anything else, cos you will be starting with a higher battery voltage than the LED.

  9. #9
    Flashaholic* kosPap's Avatar
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    Default Re: Retro fitting an LED to an old 2D flashligh

    Quote Originally Posted by madbadgers View Post
    I did want to see if there was a typical schematic that was used for these flashlight drivers so I could try to understand the topology, I am evaluating if a de-coupling capacitor across the batteries would buffer high switching currents to improve performance.
    I think most buffers do soemthing like this. They have a capacitor at the exit towards the LED to even out voltage fluctuations.
    I do nto see a reason to try anything else, cos you will be starting with a higher battery voltage than the LED.

    BTW tto much heatsink compund is not a good thing. Better have metal to metal contact.

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