DIY Current-Regulated 3-Watt LED Caving Headlamp

Back in October 2004 I put together my own 3-watt headlamp, the Snickersnee3. Four months later I finally get around to typing up the plans so anyone can make their own from a certain degree of scratch - no modding! (unless you count drilling mounting holes in your helmet)

There really isn't much to it; the components are all off-the-shelf and inexpensive. And not to sound too conceited- but for caving applications it really excels in runtime, flood output and both immediate and long-term economy. I've been abusing it for some time now and it takes it's weathering handsomely and without fault.

I do wish it had some kind of swivel, though. If anyone knows of a decent one to employ that doesn't involve harvesting/modding a commercial product I'm all ears. In the meantime, kindly overlook the zipties holding the heatsink to the helmet. /ubbthreads/images/graemlins/crazy.gif

Recommendations and critiques are welcome.

Re: DIY Current-Regulated 3-Watt LED Caving Headla

That's awesome! It'd make a great rope rescue light, I think. .

Re: DIY Current-Regulated 3-Watt LED Caving Headla

Wow, that looks great... Job well done indeed!! The heatsink on the front makes your helmet look like its ready to get into a bullfight!! /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/thumbsup.gif

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Snickersnee3 said:

I do wish it had some kind of swivel, though. If anyone knows of a decent one to employ that doesn't involve harvesting/modding a commercial product I'm all ears. In the meantime, kindly overlook the zipties holding the heatsink to the helmet. /ubbthreads/images/graemlins/crazy.gif

Recommendations and critiques are welcome.

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This is one of the biggest challenges of making your own headlamps from scratch. I have not found a way around a certain degree of canibalization.

If you have a problem with buying a whole headlamp to rip apart, you can buy just the headband with a base you could use for your own tilting mechanism from REI. Some creativity would be required to make it work, but not as much as would be needed to start from scratch. It is a replacement headband for the PT Solo. It doesn't cost a whole lot less than you could get a whole Solo/Quest/Matrix/Matrix2/Predator for. The quality is good, so there is no reason to use some cheap headlamp parts on your expensive headlamp.

Cable ties are a really good idea. You can't tilt, but it is secure. The only other problem I could see is if your headlamp failed, it would be a pain to pull it off your helmet in a cave and put on your spare. You do carry a spare, right? 3 or more indendent light sources?

The only other issue you didn't seem to adress was water and much tightness.

I like the design a lot. The heatsink with the star in the middle looks very simple and effective.
It seems the manufacturers of headlamps haven't figured out heatsinking yet. They keep making the headlamps out of all plastic.

Good luck.

I've got my Melzer Radon a month ago and have it used now for 22 caving trips.
Up to now I like it.

For a swivel: IMO used to have such a device which was intended to fit in between a standard hook mount. It was used on the Melzer Polaris.

On you website you state full power for 24 hours with 8 AA cells.
Edit: While your schematic shows 16 cells

If using LiFe cells, you get about 4Wh per cell, maybe a little more, 8 of them give 32 Wh.
Driving a 3W LED with a 90% efficient circuit will need 3.3W, so you end up at about 10 hours.
How is it possible to get 24 hours?
If you use rechargeables, you get about 2.5Wh per cell in the best case, giving you 20 Wh.
Did I get anything wrong?

I use a BP835 power pack for my Radon, which has roughly 28Wh, better packs with maybe 40Wh could be available. This one is smaller than two cigarette boxes. Acutalle a little more than the size of a usual 6 AA pack.
On full power, the Radon takes 3.3W.

For the Nova, larger power packs are available, giving longer runtime, of course.
For the AL3, it should be some 1.5 hours on full power with a rechargeable cell.

Yours is a nice light, no question and probably very good value for the money.

Yes, I made the same observation regarding the watt-hours of AA batteries and his claimed full-brightness time.

Note that while the schematic shows 16 batteries, he actually only uses 8 since he is using 4 2xAA battery packs.

I had calculated an optimistic watt-hour time of 29 watt-hours for REALLY GOOD AA batteries, giving a 3W output life of under 10 hours. In addition, since the actual power delivered to the Luxeon is at least 3.6-4W, the life would be even less.

Scott

And further, I do not believe the 95% efficiency of the power supply. But this does not really matter.

I also wonder why the batteries are mounted on the helmet's side. I experience it quite often that I have to pass a fissure which is just as wide as the helmet.
And 8AA is a little bit over limit what I want to carry on my head (but cavers have different opiniuons about that). I could use my Radon with 6 AA cell, but I prefer readily available inexpensive video camera power packs.

And Aaron: how caveproof is your light? The heatsink may protect it a little bit, but it will also be some kind of mud catcher.

One of the links (SS procedure) on your site leads to Welsh Ally medical products instead to a caving light.

Re: DIY Current-Regulated 3-Watt LED Caving Headla

I'd guess they're on the sides due to weight. If you mounted the batteries on the back it would probably tend to pull it backwards..

Re: DIY Current-Regulated 3-Watt LED Caving Headla

Not so bad, I've used two D cells on my back and it is no problem.
Necessary is, of course, a good helmet.
A carbide lamp on front is much more awkward and still useable.
But people's taste about a balanced helmet are quite different.

And BTW, I bet that the MTBF of 10000 (caving) hours is completely out of reach for a light like this one.

Re: DIY Current-Regulated 3-Watt LED Caving Headla

MTBF?

Re: DIY Current-Regulated 3-Watt LED Caving Headla

Mean Time Between Failure

Re: DIY Current-Regulated 3-Watt LED Caving Headla

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ACMarina said:
MTBF?

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My experience from the last few decades caving is, that the MTBF of homemade lights is quite short .-) (average much below 100 hours)

Of course it depends largely on the kind of caving. When I guide trips, the lights do not suffer much, as tehse tend to be easy ones.
For exploring new cave (that is the usual thing) cavers do negotioate more difficult passages and are so excited that they do not treat the equipment too carefully .-)

Re: DIY Current-Regulated 3-Watt LED Caving Headla

Ahhh, thanks guys.