custom UL headlamp

[iamscottym]

Has anyone ever attempted making a headlamp lighter than commercial models? I know keychain led's are about the lightest possible but I really prefer a headlamp. I've got a larger Petzl Tikka XP and the uber tiny Petzl Zipka, but I think I can make one smaller.

Background:
LED's need a certain amount of voltage to light (forward bias voltage) usually 3.4V on 1W leds. Since alkaline batteries provide 1.5V per cell, 3 cells are required- hence most headlamps using 3 AAA's. However, from a geometric perspective AA cells have more energy per weight than AAA's owing to their larger volume (to hold reactants that produce electricity) compared to surface area (battery casing, ie: dead weight). Therefore I want to use a single AA cell for the headlamp, and a bit of circuitry to "boost" the voltage (called a boost regulator) high enough to light the led.


Another advantage to making my own is that I can set many different brightness levels by programming the microcontroller. And of course I can use different colored leds. My though is to use a 1W white and 1W red and be able to switch between the two with the press of a button.


Features:
1 AA Lithium battery
1 AA battery holder
3.5V boost regulator circuit
1W white led + 1W red led
MOSFET
AVR AtTiny micro controller
momentary contact push button switch(different lighting modes)
sliding switch (on/off)
custom pcb

everything will be mounted on a small pcb, no lens or housing. Perhaps a bit of shrink tubing to protect electronics from moisture. A boost regulator provides 3.5V for the micro and the leds. A sliding switch turns everything on/off. The micro produces a PWM signal for a FET to adjust the led brightness. A momentary push button switch is used as a digital input on the micro to control brightness and whether the white or red led is turned on.
plated through holes on the pcb allow a piece of parachute cord to be tied on either side for a headband. a sliding knot allows adjustment.
from my calculations I can get the weight under 1.2oz, compared to over 3oz for the tiniest commercial headlamps.


boost regulator: http://www.pololu.com/catalog/product/795
battery holder: http://www.pololu.com/catalog/product/796
white led: http://www.sparkfun.com/commerce/pro...roducts_id=602
red led: http://www.sparkfun.com/commerce/pro...roducts_id=605
sliding switch: http://www.sparkfun.com/commerce/pro...roducts_id=102
momentary switch: http://www.sparkfun.com/commerce/pro...oducts_id=9190
avr micro: http://www.sparkfun.com/commerce/pro...roducts_id=211

weights (in grams)

lithium AA 15 boost regulator 2 main pcb 10 battery holder 5.67 parachute cord 1.1340

Total Weight 33.8



Given the above weight (1.2oz), that's a full 2 ounces less than my zipka (which is 2.5oz + 3AAA's).

What do you all think?

[Outrider]

I think you have way too much time on your hands!

But if 1oz is that important to you, and it works for what you need; then drive on.

[Sailor (The other one)]

I like the idea of a single AA, since every other electronic device uses AAs and the low weight is impressive. Can you make it waterproof? For use on a wet trail like the AT, that'd be a big help.

[jrwiesz]

There is already one made by Petzl. 1 ounce, red, white, and strobe in both colors.

[moytoy]

My first thought is that it's a nice wintertime project. I'm always looking for my next project.
My next thought is, can it work?
I notice the led draws 350 ma peak.
The volage booster is 300 ma ( a littler more if you lower the 5 v output.
You also have the electronic circuit to power.
You researched this more than me so I may be missing something here.

[iamscottym]

I'm an engineer and my other hobby is amateur robotics so this sort of thing is pretty easy for me.

Regarding the power consumption specs, those are rated maximums for the components, not what would actually be consumed. by manipulating component values (resistors, capacitors, etc) the actual current consumption values can be changed to whatever you'd like to improve run time, etc. If you're interested in the details I'd be glad to oblige.

Yes, this could be made waterproof (or at least very water resistant with some heat shrink tubing and a waterproof switch cover. It'd add a gram or two of weight.

Unlike the petzl e-lite, this will provide a good amount of light with a much better run time. My tikka-xp gets around 100hrs on medium setting with 3AAA's. A single AA has 25% more energy than this.

Calculation:
alkaline AAA 1.5V & 800mAh = 1.2Wh * 3cells = 3.6Wh
alkaline AA 1.5V & 3000mAh = 4.5Wh

comparing alkaline AAA's with a lithium AA as I plan to use is even more favorable towards the latter. Note: you could use an alkaline or nimh AA in my light without any modifications.

[juma]

make it and they will come...

[Skidsteer]

Features:
1 AA Lithium battery
1 AA battery holder
3.5V boost regulator circuit
1W white led + 1W red led
MOSFET
AVR AtTiny micro controller
momentary contact push button switch(different lighting modes)
sliding switch (on/off)
custom pcb

What do you all think?

Zebralight makes a light that uses a single AA battery for those not inclined to try making one.



I recently bought one and plan to do a review in the next month or so. My initial impression is very favorable. Impressive light.

[leaftye]

There's also the Fenix HP20. It's a bit brighter than the Zebra, but the Fenix does look like you can carry it as a flashlight which can be nice sometimes.

[JustaTouron]

Zebralight makes a light that uses a single AA battery for those not inclined to try making one.



I recently bought one and plan to do a review in the next month or so. My initial impression is very favorable. Impressive light.

Horrible color for a flash light.

I would paint the thing orange and add some reflective tape. If there is one thing I want to be able to find in a very low light situation such as tent at night or the bottom of my pack at dust, its my flashlight.

[Skidsteer]

Horrible color for a flash light.

I would paint the thing orange and add some reflective tape. If there is one thing I want to be able to find in a very low light situation such as tent at night or the bottom of my pack at dust, its my flashlight.

Look closely at the package and you'll see that it comes with a second holder that glows in the dark. It works great for hikers and campers:



I suppose the flat black tactical holder is included specifically for ninjas.

[frisbeefreek]

Funny--I was thinking about the same subject (must be winter fever). Basically, why does my Tikka require 3xAAA batteries (it's a voltage thing).

Ideally, I'd like exactly what you describe, because it's rare that I need 80-100hrs of burn time, but I do need the brightness afforded by the bigger lights. Also, like others, I'd like to be able to swap my camera (AA) & light batteries so I only have to carry one spare.

As an added benefit, as you mention, the the AA lithium energy density (mAh) is ~25% better (so a single AA = ~80% of 3xAAA, ignoring the voltage drop).

And anyone who has had to fiddle with putting new batteries in a Tikka knows how poorly designed the case is - You really have to fiddle to make all 3 AAA fit (granted, you only do it rarely, but still, make someone do it in the dark and cold).

Looking forward to the review of the Zebra (it's burn time seems depressingly low).

[jrwiesz]

What's the weight on the Zebra light? Just out of curiosity.

[Skidsteer]

What's the weight on the Zebra light? Just out of curiosity.

2.35 oz. with an alkaline battery installed; Slightly less with a lithium.

[Slo-go'en]

Consider using a super bright green LED instead of a red or white one. I noticed they make 8000 to 18000 mcl typcial output green LEDs in the standard T1 3/4 package. I'm going to get some to replace the white ones in one of my headlamps. That will be easier (and less expensive) than using the 1/2W green LED lamp I recently made.

Atmel AVR processors rule! You can save even more current by using a 50% duty cycle at at rate a little faster than the eyes persistance. Also remember LEDs are current devices so its better to regulate the current, not the voltage.

[Connie]

This one is cute.



Pathfinder LED Cap

"Improved design with lights on the brim as well as under the brim"

"We've improved on our popular lighted cap by adding additional lights. The low-profile on/off button is located on the visor for easier one-handed operation. Push the button and turn on one built-in LED on the edge of the brim, great for task lighting, or two under-the-brim LEDs that illuminate the ground in front of you as you walk".


I have an older model hat with three led's in the brim-edge, from REI.

NOTE: This model represents an "improved design". I know I want one.


iamscottym,

My best headlamps I have owned had the batteries on a cord, so I could keep the batteries inside my jacket keeping the batteries warm: this is best for cold weather. LiIon batteries work best in the cold and recharge faster.

. . .

[ARambler]

From what I have heard, a lot of the LED technology is the design of the reflector and lens. You may want to focus (get it on the light pattern before designing the electronics and housing. Also, the led efficiencies are improving; both the PT EOS and Back Diamond Spot nearly doubled their light output a year or two ago. Your data sheet is dated 4/05. Is it the most efficient led?
You may want to use a lower wattage red light.

It is not clear to me how valuable a regulated circuit is. The EOS is regulated but not the spot. I have been using Li AAA batteries in the Spot for a short time. I don't know how much this affects the led life.

In addition to AAA's having a low power to weight, I would prefer a battery compatable with other gear. My Steripen sterilizer uses a 3 V 123. The AA would be my second choice, as it is compatable with my gps.
Rambler

[Connie]

I found this forum.

They are real serious about leds, flashlights, components and design over there.

I found one more, too. I will look for it.

They would have constructive information and help.

Here is just one information link I found in reference to illumination and preserving your night vision.

There are basically two situations I want lighting for backpacking: 1. starting out reasonably early to get across a snowfield (not a glacier) before the sun makes it a running water covered ice field, and 2. looking closely at some "fiddly" little piece of gear in the darkness of dusk, dawn or a rain storm. I generally try to eliminate "fiddly" little pieces of gear.

That said, I like to be able to operate the head lamp, by turning a bezel for the illumination selections (quantity of light, or broad focus or narrow focus) or a push button, without having to remove my gloves.

That said, I don't like headlamps nor the NiteIze smallest light attached to their headband either.

I liked the first Mallory squeeze flashlight in my hand, or, even in my mouth.

Next, I purchased squeeze key chain flashlights.

If I had the "improved" hat brim leds, with "moonlight" to 1 lumen (3 lumens "tops" for a low selection) and a red selection, plus an illumine the trail selection, that would be ideal. My REI led hat leds operate on a CR2012 battery and a spare in the holder tucked in the hatband.

. . .

[JustaTouron]

I found this forum.

They are real serious about leds, flashlights, components and design over there.

I found one more, too. I will look for it.

They would have constructive information and help.

Here is just one information link I found in reference to illumination and preserving your night vision.

. . .

In the welcome thread they mention.....

Flashlight Forums is not meant to replace or compete with any other flashlight discussion board, but to simply offer a different kind of playground for us "Flashaholics", a haven we can come to where open and genuine communications can freely take place with few rules.

This leads me to believe there are in fact multiple discussion boards dedicated to flashlights.

[Connie]

There are. It is amazing.

I have just started finding them.

Here is my "post" in that forum:

Connie, I have been looking for a flashlight or small key-chain flashlight that goes turns ON to the lowest setting.

All I find are quite expensive "tactical flashlights" one having to "program" it and the other does have a manual dial, but $98 "on sale" I don't think so.

I "googled" and "googled" then I found your forum.

The Photon X-Light Micro, also, is not waterproof. It would be much better if it is waterproof.

It is best if it is a key-chain flashlight or it has provision for a "lanyard".

I think the lowest setting on the Photon X-Light Micro is 1 lumen.

Maybe people, here, would know where I can purchase a relatively inexpensive 1 lumen long-lasting battery key-chain flashlight or small flashlight with provision for a "lanyard" that will turn ON to 1 lumen?

There is a guy in that forum that makes titanium housings for Fenix flashlights.

There are component programming discussions.

Right after me a wholesaler registered in the forum for products and ideas as well as sales.

4Sevens has a new design flashlight I may purchase. Oh, and look at this: a led on a toggle.

Amazing find. I am so appreciate of the OP for getting me started thinking about the problem more.

I also like the OP links for supplies because I am "into" amateur radio. Thank you, OP.

. . .