Link to Article added 1/12/07
See the article: Night-O Headlamps Article for the full background to this forum thread. This article will be added to from time to time as the project develops.

I’m toying with the idea of developing myself a new headlamp for orienteering (by way of a potentially useful (and straight-forward) electronics project).
I’ve dabbled with home-made headlamps for almost as long as I’ve been night orienteering, and although I currently use a very serviceable 10/20W halogen lamp, albeit, with a home designed and constructed battery and charger), I’m interested to see what could now be produced that would fulfill the design remit of:

a) lots of light for a long period of time
b) good useable beam pattern
c) comfortable to carry
d) light weight
e) robust
f) uncomplicated design
g) not too expensive!

What got me thinking about this is the observation that even something as apparently simple as the design of a battery powered head torch has benefited from the evolution of technology. My observation came from a re-examination of my (now aging) battery pack, which is based round five Nickel Cadmium (NiCd) cells. I have found that NiCd technology is significantly heavier and more bulky than the more modern equivalent capacity Nickel Metal Hydride (NiMh) batteries that seem to be generally available now. I am interested to see how the advance of technology may’ve influenced other parts of the headlamp design.

A bit of digging around on the web (primarily in the areas of caving, mountain biking and adventure racing) has shown that there is quite a lot of activity in the area of lightweight personal lighting at the moment.
Technological trends appear to be taking the leading edge designs well away from halogen bulb based designs, through the relatively complicated and expensive HID (High Intensity Discharge) bulb models, and now into the realms of LED (Light Emitting Diode) based lights. The light producing efficiency of high powered LEDs is now starting to surpass that of fluorescent tubes (and are easily much more efficient than filament bulbs).
LEDs (essentially solid lumps of plastic with electrodes embedded) also have an inherent resilience compared to any bulb made out of glass. On the negative side, there usually has to be some control electronics for the LEDs, and the higher powered versions have to be built in such a way that the LED devices themselves can be cooled (even with LEDs, most of the electrical energy from the battery is converted to heat, though nothing like as much as with light bulbs).

There’s little argument that a 10/20W halogen bulb based lamp is easily adequate for almost all normal night orienteering, but it’s interesting to explore other possibilities.
It may even be possible to come up with a design for a high performance, cheap-n-cheerful design, made out of easy to obtain items that could make night orienteering with a decent lamp a more accessible for more people. The possible basis of such a design could be one of the cheap sealed unit low voltage halogen lamps that are currently popular as down-lighters in kitchens etc - just work out a good way of mounting it on your head and an affordable 12V battery, and you could be there! There again, things are usually not this simple!

Just wondering what experience people have with the various types of lamp.
I await your responses!

Peter

As someone who quails at the prospect of forking out the thick end of £200 for one of those superlamps and all the chargers, vests and so on to charge it and carry it plus the spare battery, I wish you the very best of luck.  I have looked on Ebay and other places but it seems no ever sells the proper ones secondhand.

I use a Petzl Myo, which is useless but has the overriding advantage that it provides a super excuse for my poor performance.
(I use other excuses for daytime events.....)

I have a myo too. I quite like mine. The LED setting is great for reading maps (the colour seems more accurate and there is less glare) and although the main “tungsten” beam does not light up the forest like the searchlights some people wear, with a brand new set of batteries it does well enough for a plodder like me. Anyway, groping around in the dark more or less describes my normal style of navigation!

I would be interested in the outcome of Peter’s experiments. There has to be something in the new technologies both in batteries and in light sources. I am not sure where it will all end though - surely running around with the equivalent of a rally car’s lights on your head misses the point of night orienteering. It also worries me slightly if it becomes an area of the sport that depends on the runner’s ability to buy super technology rather than the mixture of fitness, skill and low cunning that usually leads to success.

I take the point about superbright lights making it a little like you’re going round the forest in a rally car, however, I don’t think that having a bright light is any guarantee of being able to complete the course any more successfully. You still need to apply your basic O techniques (primarily: navigating swiftly to a good attack point and then making a careful final approach) and the main use of the lamp for this is to read the map. The brighter lamp then might give some help in traversing the terrain more safely at speed, but that’s about the main advantage. The negative side is having to carry around the extra mass of the big light-set.

Anyway, part of my tack on this is to explore some of the possibilities of relatively cheap and simple DIY lamps. Interestingly, I met a chap on the start line at Trosley CP (Sat 17th Nov) who had made something along the lines of the model that I suggested as a possible cheap and cheerful approach (based on a domestic low voltage halogen downlighter bulb sealed module. We didn’t spend long discussing the finer points (had a race to run after all!), but the lamp appeared to consist of one of these LV halogen modules held onto a simple aluminium “L” bracket with a section of “chocolate block” terminal strip. I couldn’t tell how the metal bracket was attached to the mans head (and I know from experience that designing a practical head fitting takes quite a bit of trial and error) or what the power source was (I suspect a Nickel Metal-hydride battery of some sort). It looked pretty effective and cast a reasonable amount of light (most of it in a narrow concentrated beam). I last saw a similar DIY effort to this at a night event in holland several years ago. At a guess, I would estimate that (if you had the odd bits of scrap material around, or were otherwise prepared to improvise) you could make a 12V sealed lead-acid battery version of one of these lamps for around £30. The discharge characteristics of the lead acid battery might not be ideal for this type of lamp (halogen bulbs work best on a constant voltage supply and the lead acid battery voltage drops significantly from full charge to a disharged state throughout it’s discharge period), but it’s a cheap way of making a portable power pack with a respectable (if relatively heavy) energy capacity and might be ok.

For those with LED based lamps, it may be possible to boost the output by simply replcing the LED(s) with more recent and more light efficient models - would depend upon the components used in the original lamp.

My current investigations have me looking at a three(?) LED solution with off the shelf optics and a constant current control circuit, powered off a 12V (probably NiMh battery) source. I’m still looking at the options before committing any cash. Sourcing the components is tricky, since the most efficient LEDs at a reasonable price seem to be currently made by a Korean company (Seoul SemiConductor). I haven’t been able to find any UK based agents for SCC yet, though they are available in USA and mainland Europe. A few other large companies (e.g. Cree and Lumiled make LEDs that are almost as bright and may be easier to obtain). My preference is to use a purpose made constant current module, but best options for these seem to be similarly USA originated. UK suppliers of the critical components generally seem to have narrower ranges and are significantly more expensive. An estimate of the cost of the lamp part of this 3 LED headlamp set (including control electronics) is £40-£50. The LEDs are about £6 each, optics £4/LED, controller £15, switch £2. The enclosure for the lamps would be improvised (i.e. free) for the purposes of trialling the principal. Light output should be comparable to that of the ubiquitous 20W halogen lamp currently used by many night orienteers (450-600 lumen).

My idea for the “ultimate” version of this design (using currently available LEDs) might be a 1000-1500 lumen, 9 LED model (i.e. similar brightness to a 40-50W halogen bulb). There would be significant technical hurdles to overcome (dissipating the excess heat and I would possibly have to design and build the electronic control from scratch), and the solution may be more bulky and heavy than I’d prefer. A project for later, I feel!

Battery technology has moved on, and those with deep pockets would now be considering Lithiun Ion (Li-ion) based batteries (as currently used in digital cameras and mobile phones). Trouble with Li-ion is that, for the amount of energy needed (i.e. the capacity of the battery), batteries made of Li-ion cells would be more expensive than I would like to pay! The most cost effect solution at present is still Nickel Metal Hydride (NiMh). A 12V (nominal) NiMh battery would need 10 cells. The good news about efficient LEDs is that a lower capacity would be acceptable than that needed to power the thirsty halogen bulbs. Battery cells vary significantly in price depending upon where they are bought from. Tagged (to make soldering easier) 3AHr NiMh cells are currently available from RS components (not usually the cheapest source) for about £7 each. It may be possible to find equivalents for £4-£5. Battery cost therefore £50-£70.
Li-ion cells are less common, but there are a few complete batteries available. RS sell a 6000AHr 14.4V battery for £186 + Vat! I think that we’ll be looking elsewhere/other technologies!

Have you considered a burglar alarm battery? These have 12V output, and are definitely small enough to be considered portable. A quick search on ebay brought up two, each £5-6 plus postage. They are lead acid, and although sealed, I don’t know if running with them is feasible. They have a capacity of 1.3Ah-1.9Ah.

Regarding the brightness of lamp proposed, is there a pay-off with regards to brightness for distance and map-reading vs losing one’s night vision? If I’m walking at night, I end up seeing a lot less just after using my torch, because my eyes don’t adjust back to seeing detail in poor lighting very quickly. I hope I’ve explained myself!

I’ve ordered the components for my first stab at a LED headlamp and many of them have now arrived. Now that Southdowner is at the printers, I have a little bit of time to play :-) .

I’ve updated the original article http://www.southdowns-orienteers.org.uk/index/articles/night-o-headlamps with progress to date.

In choosing the light end of your electronics - I was going to say “bulb” but I’m not sure that word is still covers all the options - be careful to consider the slight differences in the colour of the light emitted.

At last year’s Harvester, I found it impossible to pick out the brown contours against the rough open background of the map using my normal light. Those of you who know Penhale will appreciate that I was having considerable difficulty navigating without contours!

Fortunately, my main light started to fade (my first lap runner had already used it for an hour after his light failed) and I was forced to switch to my little Petzl back-up. Although this gives much less light, it uses LED’s which give a bluer light, and I was delighted to find that I could now read the map!

Peter - if this thing works, how much will you charge me for one? I see a bright future for a clever entrepreneur.....

Lets see how things turn out Martin, before going that far - I’m cautious in my development of the project - want to make sure that it becomes a usable design.

Things have been progressing well, however, and I have produced a Technology Demonstrator model “TechDem1” to try out the ideas. It’s a cut down version of what I’m really aiming for, but seems good under lab conditions. I’m intending to try this out at the Wimbledon Common SENiLe event tomorrow.

Read all about this on the revised article.

NB. I wish I could work out how to post pictures here!

All worked well at Wimbledon - better than I’d really expected for a first field trial. The lamp gave out a nice usable pool of light on the ground and was good to read the map with. Physically, it stood up to all the rigours of the event (including scrabling through a thicket). Absolutely no problems with heat or battery failure and all parts seemed reliable. I resisted the temptation to run round the course using the fast strobe mode (- just because I can!) as a distraction weapon for the other competitors!

There will be a second trial this Saturday at the British Night Champs. There has been quite a lot of LED lamp development going on by some Night-O people in other parts of the country. It will be interesting to see what lamps the others are using.