# An Idea for a heat sink to replace H3 bulb with LED



## Norm (Aug 10, 2007)

Making a heat sink to replace a H3 bulb would give us access to cheap hosts, for instance million candle power lantern type host, making it possible to have an LED run at maximum current and still have long runtimes because of the extra room for batteries and the advantage of a larger reflector.
I've just started to think about this, so all suggestions are welcome.
I don't even know if the reflector in one of the lights is suitable for LED.
Here is what I have in mind.
The heat sink would be retained in the reflector by the earth screw. The reflector I have is metal so there should be no problem with heat sinking.
Any suggestions welcome, If someone decides to make one, please make two 

My idea would require a heat sink something like the picture, no dimensions at the moment but I could add them if someone is interested in having a go at making it. I don't have a lathe







Same picture with the bulb overlaid to give an idea of relationship of the bulb placement to the heat sink.






This is the sort of thing I had in mind. But with a broader base for extra heat sinking.





From this thread http://www.cpfmarketplace.com/mp/showthread.php?t=141994
Thanks AW I hope you don't mind me using your picture as an example.​


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## Quickbeam (Aug 10, 2007)

Keep in mind that you would want your LED to be at the same level as the filament in the glass capsule for proper focus... Otherwise, it looks/sounds like a decent idea!


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## legtu (Aug 10, 2007)

and don't forget about heat dissipation. moving heat away from the led is just the first step.


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## yellow (Aug 10, 2007)

Sorry to say, but in all the reflectors I tried Leds in, they have to be placed WAY other than where the filament was - much less inserted.


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## Norm (Aug 10, 2007)

Perhaps a prototype with a threaded post for the LED would be the best way of determining the best focus point. I'm going to have a go using a piece of 6mm aluminium cut out with a hole saw and a brass bolt for the LED post, using two nuts I'll be able to move the LED position, it might be best for any heat sink to be made this way, so as to allow for adjustment for any reflector. If someone could machine something in aluminium that would be perfect.
Norm


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## wquiles (Aug 10, 2007)

Norm said:


> Making a heat sink to replace a H3 bulb would give us access to cheap hosts, for instance million candle power lantern type host, making it possible to have an LED run at maximum current and still have long runtimes because of the extra room for batteries and the advantage of a larger reflector.
> I've just started to think about this, so all suggestions are welcome.
> I don't even know if the reflector in one of the lights is suitable for LED.
> Here is what I have in mind.
> ...



Good idea. In fact it was such a good idea that I tried that over a year ago. You can see the hand made prototype heatsink I created in my old post: 

http://candlepowerforums.com/vb/showthread.php?t=123003

Final design:






It does work, but the reflector totally sucked with an LED source  . If you were to try it with a different reflector you would probably get different (hopefully better) results 

Will


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## Norm (Aug 11, 2007)

Thanks Will, just goes to prove that there is no such thing as an original idea, very interested in what you've done in your thread, it is exactly what I had in mind except I wanted to leave a larger disk at the back of the reflector for heat sinking. How well did the one you made handle the heat from the LED?
Interestingly the bulbs must have some variance in the the position of the filament the bulb I have only measures .63" where yours looks like it was .80"
Thanks Norm


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## wquiles (Aug 11, 2007)

Norm said:


> Thanks Will, just goes to prove that there is no such thing as an original idea, very interested in what you've done in your thread, it is exactly what I had in mind except I wanted to leave a larger disk at the back of the reflector for heat sinking. How well did the one you made handle the heat from the LED?
> Interestingly the bulbs must have some variance in the the position of the filament the bulb I have only measures .63" where yours looks like it was .80"
> Thanks Norm



Norm - I don't mean to discourage you - You still have a new/novel idea with the larger heatsink; mine was something slightly different trying to replace the actual bulb 

As to the height, I actually found out by experimentation that I had to move the module back in order to get best focus, so yes, .63" or even less would be nice. The problem is trying to use a reflector designed for the bulb to work well with an LED that has a different light radiation pattern 

Will


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## Norm (Aug 11, 2007)

Not discouraged at all Will, just interested to see the work you had done.
Norm


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