5W headlamp with adjustable BB750

my first mod in a long quite awhile. here's a pic of the output, which is very much under-driven but i'm not sure how much exactly. basically i just turned it down until i could run it without the heatsink getting too hot since it's in a plastic body.



this pic is with EL's 30mm optics. the picture isn't quite right, unfortunatly the checkerboard die is still plainly visable and the color is more yellowish. i took this mod into a nice sized cave last weekend (the big room football field sized) with the NX-05 optic and decided it was too much of a flood beam. Haven't tried the 30mm optic in the field yet but the beam is noticably better.

at it's current current setting (/ubbthreads/images/graemlins/crazy.gif) it's lasting about 5 hours at constant brightness on four AA GP 1800mAh NiMH batts. Pretty good considering the output. the standard bulb has the same longevity and the LS blows it away in output and color temperature.

more pics...





it's well into hour 5 and still going strong, i'm going to wait until it starts petering off before i open it up for better internal pics.

btw, the doaner light is a hybrid of Easter Seals Headlamps, the battery pack is the yellow waterproof 4AA and the head is the normal red type.

*****

my old NiMH that have been sitting around doing nothing for two months must have needed a charge cycle to get back in the swing of things. the light stayed constant for over 6 hours this time. unfortunatly now it's too late for pics, time for bed =P. i'll try the write-right trick and post those results as well, thanks for the tip mcgizmo.

Nice mod, Papasan! I think you might find that a 1/4" diffusind disk between the LED and the ball portion of the lens will eliminate the grill but still give you a good beam. I assume that the grid is larger and outside the brighter center beam?

- Don

yeah, the grid portion is only visable in the corona. btw, it's much less noticable with the 30mm optic then the NX-05. i have a piece of write-right at the end of the optic to smooth things over a bit. so if i put this inside the optic i'll get better results?

also, forgot to mention that i tried the stock reflector for this light but it didn't work out well at all. it's too shallow though plenty wide.

ahh, the little one is finally asleep, i'll get some pics in now...

Papasan,

From what I can gather, the significant portion of the beam is produced by TIR of the tube and collimator. The corona is produced by the small ball portion of the lens and this is what projects the grid. A 1/4" disk of write right in the tube, between the ball and LED should round and fuzz the corona whereas the centerportion of the beam will not be reduced in intensity or sharpness (no difussing material over it) You may notice a slight null in the center of the beam without the write right but I don't think this is a problem in actual useage.

- Don

Papasan, nice mod! I was looking for something similar to what you have done, but for use as a bike light. I'd like to see more pic's when you're done testing.
Great job /ubbthreads/images/graemlins/cool.gif
Russ

Very nice!
How does the output (subjectively) compares to an Arc-LS - specifically after about 4-5 hours?
Lifetime/duration when using high end alkalines?

I don't have an arc-ls to compare it to, unfortunatly. i do, however, have a lambda ill-pill in a mini-mag that i can pit it against. work has been hectic, but hopefully i can find some time to do it this weekend.

finally got some internal pics. the 30mm optics work out much better than the nx-05 in-cave. the biggest problem is lack of side-spill light, but i never got tunnel vision (which i have gotten from too directional lights in the past) so the side light must have been adequate.

mcgizmo, you out there? i tried your 1/4" piece of write-right but i couldn't get it to comfortably stay in the optic. the inside of the 30mm is convex (bended back out towards the opening) and all i could get to stick down was the middle part. when i tried to push the edges down the opposite side would pop back up. any hints? the waffle pattern isn't very noticable when in use anyhow, just when it's directly thrown onto a solid white wall.





i turned it up a little, more for the color than because it doesn't put out enough light. this light just blew away the petzl zooms in a cave last weekend. the only thing that came close to it's output (and beat it really, though the color was a crappy orangish yellow) was a TAG light with a big gell battery that only lasted 4-5 hours.

http://www.caves.org/imo/recharge.htm

pretty sweet light, i've already had several buy offers if i decide to make more (doubtful with my current time-eating job).

the 30mm optics also, i've found, are focusable. distance the optics from the emitter and you'll get a decent flood light.

about the only thing i would change would be to upgrade the heatsink from a piece of PCB to a solid piece of aluminum, something i'll definatly change if i do this project again. it works well now, after a couple hours on the copper was fairly warm but you could hold it fine.

Papasan,

Nice job! On the write right,it doesn't need to conform to the ball of the optic; merely lie between it and the LED. If the grill pattern doesn't bother you, heck, don't even use it!! Since I used a piece of LSD film, I think it has more body than the write right and as a "firmer" disk, it just hangs in the cavity between ball and LED. One of these days, I am going to try taking a drill bit and flatten the ball portion of the lens and then polish the acrylic back up and see what that does.

If you are moving the optics for changing the beam pattern, you definately don't want a loose piece of plastic in there. /ubbthreads/images/graemlins/grin.gif

- Don

oh yeah, almost forgot.

left is my 5W creation, about 3 times brighter (sorry, no meter) from the lambda batwing 'ill-pill' that's seen some use. top center is an ARC-LE for reference as well. the ARC has an old alkaline in it, the others are 1800 NiMHs.



and thanks for the praise, mcgizmo. considering your creations i take your compliments highly.

I have been considering doing a very similar mod. I already did one with 30 Nichia's in a Easter Seals, but it has very little throw.

I was always scared that the metal would get too hot inside the plastic body. If the excess room in the rectangular portion of the head were full of aluminum, do you think it could run at full amperage?

What did you put over the optics to give the diffused look. It looks like it won't hurt the kids, that I take on caving trips, eyes as bad. /ubbthreads/images/graemlins/cool.gif
Very nice mod. /ubbthreads/images/graemlins/buttrock.gif

papasan,

Nice mod!

About the BB750. Can you get it to dim down real low with that circuit? Say down to about Arc AAA brightness?

blue_shift, i did a 17 LED nichia mod for an easter seals headlamp as well. for the mod i used a bunch of different LEDs (basically all that i had left over from previous experiments). that one actually put out more heat. rather, it put out enough heat to send itself into thermal run-away and turn a couple of the LEDs into dim, cyan colored mutants. a single 5w or 1w solution is much more elegant and versatile, i believe. i'm not sure about running it at full amperage even with a larger heatsink, the heat build-up is probably exponential and i wouldn't trust anything that was too hot too touch for fear of melting the case. and i used a product called 'write-right' to coat the end of the optics, it's similar to satin finish clear gift wrapping tape. in fact, some people don't bother buying write-right, they just use strips of tape.

lux, not sure how far down it goes, i'll try it out next time i open it. after 6 hours of light it'll get pretty far down there tho =). it's not really meant to be adjustable in the field, i decided not to put any pots or dimmers in because i wanted to preserve the water-proofness of the case. as a consequence, it takes a bit of doing to get the top off, adjust the trim pot and put the top back on while aligning the optics. not super hard, but it takes a couple minutes.