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Adam Rothermich
(aroth87) - F

Locale: Missouri Ozarks
MYOG headlamp? on 08/21/2007 20:56:02 MDT Print View

So, being the good EE student I am, I was looking at getting a lighter headlamp and thought, how much can there be to it? So I broke open my PT Aurora and had a look and wasn't very impressed. It had some special stuff for the strobe modes and such but I never use those anyway. So I looked on the internet to see if anyone else had tried their hand at making one. I didn't find much and what I did find were fairly simple with just some LEDs in parallel and a resistor in series to drop the remaining voltage and control the current.
I figured I could do one better and stick a zener diode in parallel with the LED's for a little better voltage regulation. I'm not sure how much difference the zener will make but they're cheap so if I decide its not worth it I won't be out but about $0.56. I'll also be using a pair of 3 V lithium coin cell batteries for power to make a nice, light, compact unit. I'm not sure what it is going to be mounted in just yet, maybe an Altoids tin, and this version will only have one brightness setting, ON. I'll play with resistor values to find an acceptable brightness output before I go soldering things together. Oh, and I'm planning on using the elastic strap with cord lock ala the e+lite to keep it attached to my body.
I priced all the components and it comes to $7.00 for everything but the battteries, Altoids tin, and elastic strap. Not bad when something like the e+lite will run you $30. Sure it has more modes and a more professional look, but at this point there's so much homeamde or cottage gear in my pack that something that nice would look out of place!
So has anyone else thought about making their own headlamp, or even better, actually done it?
I'll try to keep you updated as I progress on this.

Adam

Mike Barney
(eaglemb) - F

Locale: AZ, the Great Southwest!
Re: MYOG headlamp? on 08/21/2007 21:07:45 MDT Print View

I built several. As for your cost estimate, manufacturers often have about a 25% materials cost based on MSRP, so that's pretty close.

What I found was that while I could put together a pretty good regulator and array, and at the time more and brighter LED's than could be had at retail. hey had spent the time in the human factors and packaging, and that was ultimately a pretty big deal.

If you want UBER light, search for a 5 Watt Luxeon white LED. I believe that is as bright as they come for non-coherent sources. They also make a pulse driver that is pretty impressive. You can play the duty cycle game for extended battery life.

Good uck,
MikeB

Brett .
(Brett1234) - F

Locale: CA
MYOG headlamp?, or here for $5 on 08/22/2007 02:13:16 MDT Print View

Adam,
I was going to make this one..
http://www.instructables.com/id/EU9I131F1B3RHOB/
(many more at that site)

Until I found these guys and their 8-LED (High,M,L) AAAx3 tilting headlight for $5 with free shipping.
http://www.dealextreme.com/details.dx/sku.1298
Here's a headlamp wih an additional LASER
http://www.dealextreme.com/details.dx/sku.1299

But since you are an EE; do build your own and consider it career experience.

Graham Williams
(crackers) - F
Re: MYOG headlamp? on 08/22/2007 14:05:32 MDT Print View

I made something along these lines:
http://www.instructables.com/id/E2K9BN5EDKEUBYRD9V/

It's in pakistan on expedition right now, and I'll let you know the report on it when it comes home in about two months.

Adam Rothermich
(aroth87) - F

Locale: Missouri Ozarks
MYOG headlamp? on 08/22/2007 20:18:06 MDT Print View

Graham, that's a great headlamp, but 1 lbs and $60! I'm looking for something a little simpler, cheaper, and of course, lighter. Thanks for the link though, I may be able to find something that will help me out in it (I haven't read the whole thing yet, just browsed it).
Brett, now where is the fun in buying something I could try to make for almost no investment? :) Likewise, I would like something a little simpler and lighter, though I don't think I can find anything cheaper!
I think I'll run to Radioshack tomorrow or Friday and see if I can pick up any supplies there, otherwise I'll order all the parts this weekend.
BTW guys, thanks for the links, I had forgotten all about instructables.
Mike, since you are probably more knowledgeable than I in these kind of matters (I'm drawing on material I learned in a high school class 3 years ago), do you think the zener diode will have much effect on the life of either the LEDs or the battery, or should is there something else I should consider in the way of regulation?

Thanks,
Adam

Mike Barney
(eaglemb) - F

Locale: AZ, the Great Southwest!
Re: MYOG headlamp? on 08/22/2007 20:52:24 MDT Print View

Here's the deal on regulation: If you can get away without it, you're a little bit better off. If you're going to burn out the LED with a regulator, then obviously you need one. A zener in the simplist form dumps power unless you're using it as a reference for an LED driver.

What I really like right now are some of the cheap single chip PWM or duty cycle controllers: They're incredibly efficient (often mid 90%) and easy to 'dial a brightness', have hard stops on the max delivered power, without smoking the LED.

It also turns out, that there is a super easy, super lightweight well matched, no regulator needed approach:
Get an IL-2200 C sized Lithium 3.6 V battery, connect it to an uber bright white LED that is rated at 3.6 V, and let it go. It will run for days, and stays pretty bright until it's almost out, ie a very steep discharge knee.

Hope that helps,
MikeB