[HeadLamp]-custom made

[aranwe]

Hi there,
so where to begin ... i hike/backpack quite a lot so i want to replace my old flashlight, after trying friends headlamp i know i want it to be headlamp (from now on referred as HL) :tinfoil: ... but there is always a catch all the normally sold HLs are in one way or the other real compromise or too expensive (like petzl ultra / silva alpha in CZE like $450+) so i decided to create one but i need some help

Features

• i want it to be able both run long on batteries with low light output and if needed to shine bright as hell
• running in voltage range 4,8V-6V -4xAA batteries (to be able to run on NiMHs and alkalines)
• battery pack on cable a) attachable on the back of HL b) able to put it to pocket in winter
• price for parts - ~20-25$ - from what i see i guess i'll get a bit higher

Buy List

• Cree XPG R5
  

LED diode
ok ... so i guess i figgured out myself that the most efficient led nowadays is cree xpg r5 ... so its the winner (if anyone has some other opinion on the most efficient led on low current - give me tip )

Reflector and Lens
Reflector will be needed i guess because i want more floody HL
Lens are needed only for throwers right ?
i was thinking on using ~52mm reflector and instead of lenses some cheap (if able to get) 52mm photo UV filter
any ideas ?

Driver
this is the most tricky part i guess ...
it must be able to run in voltage range 4.8-6V ...
i would love it to be able to run on 3AAs also ... so the range would be 3,6-6V but if it would affect efficiency i'm willing to leave it off (any ideas?)
i dont know much about led drivers so here i'm pretty much depending on your advices ...
2nd thing i would TOTALLY LOVE would be if the output could be fluently controled via potenciometer / trimmer / capacitor trimmer ...
the driver works as PWM controller right ? ... so there is some resonance circuit ? ... so by controlling size of a capacitor or rezistor could i control the size of pulse ? ... anyone already was thinking about this / already done it ? ...
THE factor in choosing the driver is efficiency and price (from what i read here on forums, there are some really great drivers but expensive ... )
if the potentiometer controlling is practicable i think that i would have to design my own driver respectively redesign some nice one (and harvest parts from some cheap driver from dealextreme/kaidomain)...
(soldering / creating PCB shouldn't be any problem)

Casing+Cooling
i have access to a 3D plastic printer for like $0.64 for 1cm^3 so i'm thinking of modeling the enclosure in autocad / solidworks and printing it ... but what i'm little bit afraid of is the heat ... i don't want it to burn a hole in my head ... though it'll be running most time on "low" mode so it'll generate little heat (right?) ... second thing i need to consider is how to make the tilting mechanism ... i was also thinking about buying some cheap HL on dealextreme/kaidomain and using it as the base .... with the place left from the batteries there wouldnt be problem to cram there any driver / jack / button / potenciometer / anything ...

Straps & rest
there wont be any problem with straps and the plastics ... cheap and easily obtainable


Thank you for any opinion on this topic ... (unfortunately i didnt find any similar project here on forums so i dont have anything to get inspired from )
BTW: if i did anything wrong, please be patient, i'm new on this forum and new to led lighting

 

[ahorton]

...all the normally sold HLs are in one way or the other real compromise or too expensive (like petzl ultra / silva alpha in CZE like $450+)

I wouldn't consider those to be 'normal' headlamps. They are on the high-end of the price scale (and I don't think they are worth it).

Looking at the cheaper ones like:
Princeton Tech EOS, or APEX,
LED Lenser H7

what are the 'compromises' that you don't like about these? (I'm just trying to and work out exactly what you want)


These are a bit more expensive than your $25 budget but much cheaper than the ones you listed.

You may choose to buy one of these and then modify it. An emitter upgrade and a power cord extension are pretty easy and will get you most of what you want.

Buy List

• Cree XPG R5

The XP-G is an obvious choice, but my feeling is that if you are building your own you should go for more light. It doesn't take much extra cost to start using multiple XPGs and the difference is noticable both in efficiency at low power and output at high power.

While a little out of fashion these days, I'm a fan of a Cree MC-E with
http://www.dealextreme.com/details.dx/sku.13741

MC-E's are pretty cheap now and they fit inside one of these heatsink/lens combos very well. A bit of sanding on the lens and you get a perfectly smooth beam. You can still run it on low current if you like, but the option of high current is there.

Reflector and Lens
Reflector will be needed i guess because i want more floody HL
Lens are needed only for throwers right ?
i was thinking on using ~52mm reflector and instead of lenses some cheap (if able to get) 52mm photo UV filter
any ideas ?

You can get a floody beam with a lens but TIR optics are what most people use. If using an XP-G it's hard to go past the 10mm optics. Especially if you want flood.

52mm is very big. Normally people use bigger reflectors because they want more throw.

Driver
this is the most tricky part i guess ...
it must be able to run in voltage range 4.8-6V ...
i would love it to be able to run on 3AAs also ... so the range would be 3,6-6V but if it would affect efficiency i'm willing to leave it off (any ideas?)
i dont know much about led drivers so here i'm pretty much depending on your advices ...
2nd thing i would TOTALLY LOVE would be if the output could be fluently controled via potenciometer / trimmer / capacitor trimmer ...

With your battery choice, (AAA or AAA cells) I suggest:
http://www.dealextreme.com/details.dx/sku.15880
and just stick to 3 cells. It has some annoying modes but if you can live with them, then it is a quick and cheap option.

Or the variety of AMC7135 drivers might suit you. I like these with Li Ion cells, but I find all AA, AAA cells have too much voltage sag t stay in regulation for long.

For a cheap setup, a few resistors and a SPTT switch from DX will give you a few modes.


Most DX/KD drivers (that are not linear regulators) can be made variable if you find the right resistor.

A friend of mine made his infinitely variable driver by using AMC7135 chips, a programmable Atmel microcontroller and PWM. In his version you can hold the button down and it smoothly changes the level (by PWM). I don't like it because I like to know exactly what my runtime will be an each level and the infinitely variable levels makes the runtime estimation a bit fuzzy.

Casing+Cooling
i have access to a 3D plastic printer ...

... i was also thinking about buying some cheap HL on dealextreme/kaidomain and using it as the base ...

I always like to make mine totally out of aluminium. The coooler the LED is the better. If it's just a one-off, look for scraps of aluminium tubing and you'll be amazed what you can make.

The cheap DX headlamp has often caused me pain. The straps and bodies are often what failed for me. Eventually I decided that I was better off making them from scratch.

 

[guiri]

The new Fenix gives you around 225 lumens and the price isn't bad at all...

http://www.4sevens.com/product_info.php?cPath=22&products_id=1774

 

[Avatar28]

Why not something like the Fenix HP10? I realize that it is more than your $25 budget but to be honest, I think you're going to go well over that building your own anyways. At just a bit under $70 it is only slightly more expensive than the PT Apex. It seems to have most of what you want.

-Cree XR-E(R5) emitter
-7, 50, 120, and 225 (only for 3 mins though) lumen output modes
-4 x AA batteries
-digital current regulation to control brightness. As I understand it, current regulation should be a bit more efficient and more importantly will avoid the flicker that plauges most of them at lower brightness levels.

Oh, and it's a heck of a lot easier than messing with all the trouble of building your own. If you consider your time worth anything much at all you will "spend" more on the homemade unit.

Just a note about Princeton Tec too. My experience with their customer service has been nothing less than phenomenal. Twice they have offered to RMA my headlamp despite it being damaged and not a defect.

 

[ahorton]

The only reason I didn't mention the Fenix was that I don't have personal experience with it. I agree that it looks like one of the best.

As for the time 'spent' making a torch, no-one here would think less of someone who wants to make their own just for the satisfaction of having made it!