LED light from scrap and left over pieces .....

[wquiles]

Uhm… a whole pivoting heatsink? Perhaps with a lot of holes into it, for venting?

Yup, that would work better. Heat-wise, the LED's work like the CPU in a computer - it gets hot, and needs a heatsink to help disipate the heat - otherwise the temperature increases until the chip dies. But unlike a CPU heatsink, there is no fan in a portable light, so you rely on having a large surface to spread the thermal energy and exchange that into your hand and the air around the light. That is why a lot of handheld lights have fins - to increase the surface area (again, same as in CPU heatsinks). Designing and building LED lights is certainly a great hobby )

 

[mattthemuppet2]

great to see your work again Will, always a pleasure I have a long list of LED projects to get started on once we move, not much point doing them beforehand.

 

[Torbo]

I have this Dewalt 18V incandescent "lamp" what plugs into the Dewalt batter pack this model, in case anyone wants to buy one for a similar project. I trade it/barter for it many years ago, and it has been sitting in a shelf in my home office - just sitting there, as I hoped to eventually do something with it. I like it since with the heavy battery base, it can stand on its own, and have the head pivot at either horizontal or vertical, which might come handy.


I wanted to take it camping with my son's scout pack on March, but I ran into some trouble, and I could not finish on time. This weekend I finished it


I measured the threads on the head as best as I could - something like 18TPI:





I started with a scrap piece of Aluminum - gummy, does not machine well (certainly not 6061), but it was "free", so I used it as a base for this project:








To give the new head/heatsink a non-slip surface, I gave it a swirl knurling finish:





Then face, and bore for the thread side:








Then cut the threads, and test fit:








Cut the "excess" in my revamped bandsaw:





After machining the oposite side for the LED and the lens pocket, the head was finished. Here it is compared to the original plastic retainer ring:








For the LED head/heatsink, I decided on color quality over quantity, so I used several LED's with a high CRI value, which I had in my storage for 3-4 years:





and in the middle, I used on the McGizmo high CRI LED's he sold years ago:










Not pretty, but this is how I decided to plug the head/headsink to the swiveling base:





Now, since these packs charge to higher than 18V (actually in the 21V range), I decided to use one of my own PWM LED controllers, connected in direct drive (for high efficiency), and to make it adapt to the temperature in the head - so as it warms up (new/fresh batter), the PWM duty cycle gets smaller (which lowers the temperature), and once the temperature lowers, it can go back to the initial, higher duty cycle. Of course I have a 5C histeresys in the software, so that this is all very gradual, and automatic (Tiny85 gets calibrated at programming time). Of course, I can't connect a 3V PWM signal without some sort of switch, so again, I am using one of my own small MOSFET boards as the switching element. Here is the setup in my bench - I have a "sticky" thermal pad between the boards and the metal head, and epoxy to keep them in place (that schematic is the one for the "white" PWM controller board I designed):





Bench testing. The back of the my controller board has the Tiny AVE programming pins, so that I can re-program/fine-tune as part of the development of the firmware settings - right now I am letting the head get to about 48-50C before picking a lower PWM duty cycle:





Here is the initial duty cycle setting - about about 68-69% (yes, I am under-driving everything, for cooler temps, and longer runtimes):





Once the temperature level is "hit" the PWM adjustment takes place, lowering the RMS current, thus starting the "cooling" process for the LED's - here the duty cycle is 50% lower than initial, at about 34%:








Finished product:







I just simply used the original plastic lens, and glued it down in place using epoxy:




Up and running (pun intended!):





Not too bad for stuff/pieces I have laying around, right?

Exilent! Impressing!