Even though my 4000K LEDs aren’t in yet, I couldn’t help but build a prototype while I wait! I have some 5000K on hand, so I used those - I just wanted something warmer for a “lantern” style device.
Differences between this light engine and what I have envisioned for the final version:
5000K LEDs instead of 4000K
Used a 1800 Ohm resistor instead of the 1mA current regulating diode. Assuming a supply voltage of 4.2V and a LED forward voltage of 2.43V (as measured), that should give me roughly 1mA on a full battery: (4.2V - 2.5V) / 1800 Ohms = 0.00098A = 0.98mA
Jumped the switch pads with a wire instead of a switch (like the CRD, I only bought one switch)
Stranded copper wire for the conductor pillars instead of the copper rods (only bought enough for the final version)
Battery is only held in place by the spring tension. I plan on having a partial copper surround and then a velcro strap or something to make sure it doesn’t budge.
Dim mode, Bright mode
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Action video:
Another tidbit… assuming a 3000 mAh battery, this should last 8.6 hours on high or 4.2 months on low/moonlight.
Ok, I decided to go a different route for the end caps. I was trying to mostly use materials I already had sitting around (putting the B in BLF!), but that oak was hefty to work by hand.
So I picked up a piece of 1/4” poplar. I think I’m going with two stacked discs, one being smaller to fit into the plastic housing, large enough to pressure-fit in place. I’ll glue that to a slightly larger disc that will sit outside of the housing.
Here’s the rough cut with a jigsaw:
And getting to it’s final size & shape using my palm sander:
Ok, all poly’d up (6? spray coats each side with some sanding in between). Nice and snug, solid feeling.
Still waiting on my 4000K LEDs. They must be taking the slow boat from China. Once they get here, I’ll have everything to build the final light engine.
With this much time left in the contest, I feel like I should do something more to up my game. Thoughts or ideas? Something that doesn’t involve redesigning the PCBs, that is
My 4000K LEDs have arrived and I just assembled the final circuit boards.
I also cut the copper pipe that will partially surround the battery. It’s been cut to length and a strip going the length of the battery has been cut. Now I want to cut a hole in the “back” of it so I can push the battery out from behind. Kinda a mess to explain, but pretty simple. I’ll snap a pic later.
Edit: here are the final circuit boards (differences from the prototype are the switch inclusion and the current regulating diode instead of a resistor)