Headlamp Design Ideas For The Luxeon Star

I have been giving consideration to designing a headlamp, primarily for caving, but not exclusively. As I have never done caving, nor backpacking, I know little or nothing about the activities.

I have seen headlamps with straps, and headlamps with a clip, and headlamps that bolt onto a helmet. In regards to caving, which would be the best, or most typical way to use the lamp?

I see that some use a large tongue like clip on the back, which would seem to slip into something, like a slot on the helmet.

It doesn't seem like it would be too dificult to design something, especially if it is a bolt on. Or even easier if it just slips into some sort of holder?

I will be using the Blaster flashlight head, and attach it to either a plate to be bolted onto a helmet, or to be used with straps. I can go with either the 1 watt or the 5 watt, and it will use an external battery pack. For the 1 watt that would be 3 cells, and for the 5 watt it would be 6.8 volts in, or 5 or 6 cells. I would have resistance in the design, so rechargables should be okay.

Of course, the white 5 watts are not available yet, so it would be cyan.

I might be looking for a volunteer to test one out in a cave?

Wayne J.
www.elektrolumens.com

I think Nichias are better for a primary caving light than a Luxeon. Definitely not a 5 Watt as you want to use as much of your night vision as you can. The best primary light should be a wide flood, and that can be achieved with 5-10 Nichias or less if overdriven. I think this is more energy efficient than a LS. Maybe a 1 Watt spot light for distance spotting would work well especially if it could be focused tightly like a halogen lamp.

Originally posted by Ratso:
I think Nichias are better for a primary caving light than a Luxeon. Definitely not a 5 Watt as you want to use as much of your night vision as you can. The best primary light should be a wide flood, and that can be achieved with 5-10 Nichias or less if overdriven. I think this is more energy efficient than a LS. Maybe a 1 Watt spot light for distance spotting would work well especially if it could be focused tightly like a halogen lamp.

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<font size="2" face="Verdana, Arial">Okay, that's what I would want to know. Does a caver need 120 lumens of light? I guess the answer is no.

Regarding the 1 watt, it can be underdriven. This increases the efficiency quite a bit. Perhaps it could be used without the optics, for a wide flood? There could be a low and high setting.

If Nichia's are overdriven, they can easily pull 30mA each. That would be 300mA. The Luxeon Star at 300mA puts out quite a lot of light. If run at 200 or 250mA, it still puts out a fair amount of light. Perhaps a switch, with a high setting of 300mA or 350mA, and a low setting, at 200mA?

Thanks for your comments.

Wayne J.
www.elektrolumens.com

Would under driving the 5 watt LS be more efficient than under driving the 1 watt LS?

Originally posted by Nerd:
Would under driving the 5 watt LS be more efficient than under driving the 1 watt LS?

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<font size="2" face="Verdana, Arial">No, I don't think so. I don't have any numbers for you though.

Wayne J.

Wayne - Consider using something like this:



That's a 1W/O in a TO-3 Power HS. The HS is about 1/8" square, and 1.25" high. The Luxeon is nicely hidden and protected by the heat sink - the only thing that could damage it would be something protruding between the fins (and you could attach a lexan window over the fins).

The HS is rated for 25W - it keeps a 1W driven at 800mA at 34C in still open air.

I'm going to use this on my bike (as soon as I fix the mount and get a better battery holder)



I think this would make a nice base for a head lamp - should even keep a 5W lux relatively cool.

-Darin

Back few years ago (before I injured my lower back) I used to go "caving" pretty often. I can tell you that what ever you build will need to be impervious to water and mud. It will also need to be able to survive impacts with the cave ceiling, so it might be good to have some "give" in the way it is mounted onto the helmet.

I also think that a Luxeon emitter WITHOUT any collimating optic would be more useful as I always prefered a super wide-angle flood to a bright spot. To much of a bright spot destroys night vision and would tend to reduce the overall effectivness of the light.

You can get into some very wet situations in cave systems, so waterproofing has to be done. Not dive rated, but more like 10-15 feet or so.

Take into account the natural curve of the forehead, this tends to have headlamps that point UP at an angle. So being able to adjust the vertical angle of the head is important.

Runtime is also important.

I wonder if the optics unit could be mated to the bottom of a reflector???

How much light do these cavers need? That's got to be the first thing to get established. Although that heatsink above looks cool (BTW, where can I get one?), 800ma is a lot of current.

I don't cave, so I don't know, but there's no place darker than a cave, and I would find an LS at 800ma to be too much for backpacking, except for the occasional long range spot, for which I would use a handheld flashlight.

Cave Dave, help!!!

Originally posted by Lux Luthor:
(BTW, where can I get one?)

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<font size="2" face="Verdana, Arial">Digi-key! Part number: HS103-125-ND, $4.73 each

i have a couple LS headlamps i've made, both are driven to specs (~350mA) and work out fairly well for caving. the white one (an early violet-hue LS with old optics) is favored over the amber high-dome with new optics because of the color rendition, but the amber is still a very nice light.

the 1 watt LS seems to be a fine amount for the few caves i've taken it in, but it does seem to lack in side light so i tend to get more of a feeling of tunnel vision than i got with my 4 LED illuminator. but the largest gripe i have with them are the short run-times, only about 3 hours with maybe another hour or so of failing light. i've been thinking about getting twice the run-time by using a 4AA battery pack instead of a 2AA pack and wiring them 2+2 series/parallel but then i would need a different body for the mod. also, if you need any sort of throw then the white LS is useless although the amber works fairly well for throw.

the mod is a simple one using a 'kid's adventure lamp' from wal-mart ($6, waterproof) and a ZLT circuit.

i think i'll relegate them as back-up lights when i find a better main light, then the 3 hour run-time will be much less of an issue.

my current plan for a main light is an 'easter seals' headlamp (4AA) with a 5W LS without optics run directly. this headlamp has a nice large reflector and should work alright and by under-driving the 5W signifigantly the lighting level and run-time should be better for caving.

wayne, haven't you run a 5 watter this way (6V direct)? if i remember correctly you said about 8 hours of more-than-1W light? how bright would you say it was average? bright as two 1 watters?

from what i've noticed cavers tend to like headband type headlights, then they can use them around camp (cavers tend to camp alot) and such without wearing their helmet. although my main lamp will be mounted my back-ups will use a strap.

other things to keep in mind if you are designing a light for caves; make them bullet-proof - in a zero-light situation your lights are your life - this includes waterproof, solid, simple to repair, etc. try to make it light (weight-wise ), wearing a heavy light on your head for hours can be exhausting. common batteries, all of my gear (except my ARC-AAAs) use AA batteries, i really like battery commonality when i'm away from home and so i can use my rechargables in anything.

hmm...anything else i can think of i'll let you know. the community needs a good headlamp, i think. if you need anymore help or advice just let me know.

I'm soaking in all this good advice.

Thanks,
Wayne J.
www.elektrolumens.com

Originally posted by ElektroLumens:
 
[QB]I have been giving consideration to designing a headlamp, primarily for caving, but not exclusively. As I have never done caving, nor backpacking, I know little or nothing about the activities.
 
I have seen headlamps with straps, and headlamps with a clip, and headlamps that bolt onto a helmet. In regards to caving, which would be the best, or most typical way to use the lamp?

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<font size="2" face="Verdana, Arial"> 
As a caver of many years who has taken to tinkering with LEDs..
 
Bolted directly to helmet is by far the best way, although the mounting ideally should include provision for some vertical alignment of the lamp (this needs to be very robust - lamps do tend to get bashed against cave walls from time to time). If the beam is sufficiently wide angle then vertical adjustment is not required as long as the lamp points in about the right direction to start with.
 

I see that some use a large tongue like clip on the back, which would seem to slip into something, like a slot on the helmet.

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<font size="2" face="Verdana, Arial"> 
It's called a blade fitting and is pretty much a standard - it dates back to the days of those little brass carbide lamps which used the same fitting, and many electric lamps still use it. Although not as strong/foolproof as a permanent fixture the blade fitting is potentially more flexible (can fit a bracket to an elastic headband for helmet-free use). See <a href="http://www.karstsports.com/helmets.html" target="_blank">http://www.karstsports.com/helmets.html[/URL]</a> for some blade brackets.
 
Contrary to some, I would say that it is not possible to have too much light for caving - I would (and will) use the 5 Watt LED for sure (most existing electric caving lamps run at between 2 and 5 Watts on high beam and use large waist-mounted Ni-Cd or SLA batteries). Aside from their indestructible(ish) nature and somewhat higher efficiency the principal advantage of LEDs for caving are the ability to dim them - both for saving power and saving night vision (when you are wandering around in a chamber with a floor area of an acre or more you want a BIG light but when you are crawling through some poxy little hole and most of your light is reflected back into your eyes you want to turn it down a lot). Electric caving lamps usually deal with this by having two different bulbs for high and low beam - the Petzl Duo for instance was designed as a caving lamp.
 
Current electric caving lamps largely suck. Many cavers still use carbide lamps for three reasons: they are truly indestructible, they have unsurpassed light output for their weight, and the beam they put out is very wide angle and perfectly even (I'm not talking about those ancient little brass things, but the "ceiling burners" with waist-mounted gas generators made predominantly by Petzl which put out upwards of 300 lumens). Carbide has many disadvantages too - my reason for mentioning it is that it is the benchmark that 5 Watt luxeon-based lamps should be aiming to beat, rather than the existing electric technology.
 
The ultimate caving light would put out about 500 lumens of true white light yet run for 8 hours or more from a lightweight helmet-mounted power source, dynamically dimming itself in response to incoming reflected light so as to never waste power or night vision by providing too much light (because this mechanism can never be perfect there must be four or so manually-selectable power levels as well). The beam would be perfectly even and fill the entire field of view (roughly 100 degrees high by 150 degrees wide). The lamp and power source would be waterproof to ten metres or so even after having grit and mud smeared all over them by gloved hands fumbling for the switch and being bashed and scraped against walls and ceilings, for days on end. Can we do it?

The 500 lumens will have to wait a few years as will the compact power source for such a beast (compact methanol fuel cells, on the way). But 120 lumens is a good enough start, and both alkaline AA cells and Li-ion polymer cells have a power capacity of about 150 Watt-hours per kilogram meaning a 200 gram battery pack mounted on the back of a helmet can power a 5 W light for roughly 7 hours. The beam shape smoothness thing is easy using an elliptical holographic diffuser (not cheap, but well and truly worth it). The dynamic dimming of light is pretty easy using a light-sensitive resistor in the switching regulator feedback circuit, but falls apart a bit when mud gets spread over the sensor or when other lights get shone at the sensor (I'm pretty sure the latter problem can be resolved by going to a light-sensitive diode hooked up to a micro-controller, but that's starting to get complicated).
 
The last thing, indestructibility, is a lot more difficult. Any switch is a weak point no matter how it is made - you really need a rotary switch for multiple power levels but another option is to use a simple microcontroller interfaced to the switching regulator to run everything off a single push-button which can even be a magnet and reed switch. The whole light assembly can be inside a machined aluminium casing with a slightly recessed hardened glass window (and heatsink fins), and most internal components can be encased in heat-conductive epoxy. Mounting brackets, cable connections and the battery pack all need to be very solid, and there needs to be a water and mud-tolerant means of changing the battery pack over. The last aspect of indestructibility is that the light needs to be tolerant of component failure, including but not limited to the microcontroller, the switching regulator and the LED itself. By including a few 5mm LEDs in the design there are various ways of achieving this - the idea is that no matter how badly the thing fries itself, as long as you can apply power to it you will always get enough light to get out of the cave.
 
I've already applied some of these ideas myself, to a regulated 24-LED caving light, but even slightly overdriven the light output is a bit sad compared to the 5 W luxeon idea.
 
If you don't want to use any switching electronics in your light then you lose a lot of the advantages of LEDs over other electric lamps but could still make some real advances on the indestructible side of things. It will be interesting to see what you come up with!
 

Of course, the white 5 watts are not available yet, so it would be cyan.

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<font size="2" face="Verdana, Arial"> 
Looking forward to those 5 W whites soooo much. Maybe I should go cyan in the meantime, too..

Well, I am no techno buff like the rest of you but I am a regular caver and I have been waiting for a good LED caving light to be made. I was a petzel zoom man for a while until I went to Tasmania where the caves are a bit BIGGER and you need good light to last a days worth underground. I have been using a miners light which is the standard caving light here in Australia. You have the high beam and low beam setup. You need a good throw for looking down dark passages or just to see the other side of a big chamber. But the light you need most often is a good diffused soft light like an LED setup which is bright enough but not to taxing on the battery. I have no experience with the LS yet but am excited by its promise. Would one luxeon be just as good as 3 or four nichia leds?
I used to be a very pro-head mounted battery source as opposed to a waist pack like a miners light uses. But the big advantage of the miners light is the rechargable aspect and the longer battery runtime.
Both are good for different uses.
So...this is probably not a possible configuration but it would be great if a head was designed and like an Arc LS, different battery sources could be utilised. i.e. a cord would connect it to a small say 4 AA battery pack which sits on the back of the helmet, or a longer cord that runs to a waist mounted 6v battery. Not possible? The difference between the two would be runtime. Super long runtime for big caves or less runtime for the smaller caves.
Just a thought.
Whatever it is the ideal is predominently a good diffused LED light as bright as possible yet takes little out of the battery. Another main light like an incandescent or some LSs or even a Zenon? the Surefire bulbs. They seem to be nice and smooth like an LED light. The last thing you want in your main light is a really tight orange spot with shadows in it.
I'd love to test out your lights for you if no one else has put their hands up. It'll do some good caving!
Good to hear of your ideas.

if i remember correctly, a 5mm LED puts out about a lumen. so a 5W LS driven to specs would put out the power of about 120 nichia LEDs. 3-4 and then some =).

it's hard to imagine a cave that would need 500 lumens to light up unless it was just a HUGE space and you wanted to light up the whole thing with one source. then again i've never been in a truley large cave, not even mammoth in kentucky, so my experience is limited. 120 seems like complete overkill for most things, but if it went from a super flood (ala carbide) to a spot then i think it could be quite useful.

another good reason for carbide is that you can look at it without killing yourself because the light emission is coming from a much larger surface area then a single LED, perhaps some sort of diffuser placed directly over the LS?

Design of headlamp varies a lot depends on your target market. Backpackers, casual campers, mountaineers and cavers might have different needs. Even for cavers, caving in huge cave or narrow passages would be very different.

Like other members said, multiple brightness settings is important. 1 LED might be too bright inside the tent, 3 LED might be too bright for cooking, 5W LS might be too dim for an unfamiliar big cave. Tough, isn't it? That's why most headlamps manufacturers produce *many* models for different needs.

Look at Switchback, it has 2 brightness settings on its incandescent lamp plus 3 additional LEDs, not to mention its built-in battery carrier for 2AA plus external detachable battery pack for 4C (serial/parellel). Sounds ideal? Not really, it still doesn't fit some serious headlamp users. Very discouraging, isnt' it:-?

I think XTrem seems like ideal. Its price tag, 5W LS and no evaluation review from any users hold me up.

Nonetheless, if you come up with a solid 5W LS with multiple brightness settings, you will get one order at the least, from me

Alan

The 1 watt LS is equal to about 10-15 white Nichia 5mm LEDs. Depending on the optics, and dome, you get anywhere from wide spot to very small spot.

I do believe the rule in caving is that you carry three of everything, particularly lights.

If you can figure out how to use a textured reflector (metal is preferred) and get even a 1 watt LS to have both a nice tight spot when focused, and a reasonable smooth flood unfocused, this will be nearly ideal. The main thing is proper heatsinking. Power source: 4 C cells in series/parallel in 2 packs for a better distribution of the weight.

I have a Coleman Peak 1 Expedition Headlamp. It has a faceted reflector. When focused the spot is very smooth. However, when you unfocus it, the light pattern sucks, as you see the facet images in light. This is on of the light I am going put the Versalux PR2 LED into and hope it works. If not, the it gets cannabalized for the battery pack.

If the runtime off of 1 pair of C cells is more than the ideal stated above by experienced cavers, then a single 2C rear mounted pack would be ideal. Maybe even design it with NiMH in mind.

If you can get 24 - 48 hours runtime out of 2C, plus meet everything that would make it super attractive to cavers, then you will have a real winner. Even for non-cavers this would be very nice.

Lots of ideas and needs. All you have to do now, is find the sweet spot.

What I am going to do is compile a list of options from this thread. I'll give consideration to these suggestions in my design, which I will describe later.

Wayne J.
www.elektrolumens.com

Wayne, to throw a wrench into the monkey here, keep in mind that there are different types of helmets. So, something that has different mounting options, including a standard 1 inch headband like the Solo or Petzl Zoom, with helmet clips, plus blade and bolt on mounting should cover everything in the final production design.

Originally posted by evan9162:
</font><blockquote><font size="1" face="Verdana, Arial">quote:</font><hr /><font size="2" face="Verdana, Arial">Originally posted by Lux Luthor:
(BTW, where can I get one?)

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<font size="2" face="Verdana, Arial">Digi-key! Part number: HS103-125-ND, $4.73 each</font><hr /></blockquote><font size="2" face="Verdana, Arial">evan,

Does the LS/O fit right into that heatsink, or do you have to cut away at it? Also, you give some current and temperature figures above, but how do you have it mounted? Are you using thermal grease or Arctic Silver or something?