Super bright Green LED headlamp

[Slo-go'en]

I bought a 1 watt, green LED rated for 75 lumins with 3.3V @ 350 ma. Mounted it in an old headlamp assembly which had an incadesent flashlight bulb in it before I tore it out. Man, this thing is bright! :sun

Why Green? Because this is the color our eyes are most sensitive to.

A freind of mine asked me to make him one with four 1W LED's, like one he saw on the instructables web site. But at $9.00 a pop for the LED, I decided to try just one for starts. He wants to use it for night skiing, so maybe he does need four. :-?

I'll take it for a short walk in the woods in a few hours once it gets dark and see how well it lights up the snow, compared to a standard white LED headlamp.

[Spokes]

Cool. Not sure about the green light but I always got compliments from other hikers about my red lens headlamp.

[Snowleopard]

In earlier LED days, some of the colored LEDs were a LOT brighter than the white ones. I did fool around a bit with a green led in a headlamp, and it was bright and eerie. Let us know how it works for him skiing.

You may need to do some sort of heat sinking. If you're not familiar with it already, check out http://www.candlepowerforums.com/vb/

[Panzer1]

I have a green LED light and I like it. Its easy on your eyes in the dark.

Panzer

[slugger]

Is it easier on your eyes then Red? I know red will keep your night vision intact.

[Slo-go'en]

I went for a short walk in the dark woods with my new "green lantern" headlamp and I like it. Green is definately easier on the eyes in the snow than white and a lot brighter than red. Now I need to work on getting the beam a bit narrower, as the housing it's in now makes a really wide beam.

As it is, it is good for hiking/snowshoeing/cross country skiing, but I don't think I'd try down hill with it. Your just moving too fast going down hill skiing.

As for a heat sink, I paid extra for one pre-mounted on a small aluminum substrate which is sufficent for now and makes it easier to work with. If I decide make some electronics to drive it harder, maybe then I'll have to add to it. That will be a trade off between brightness, battery life and/or battery size.

[Slo-go'en]

The "Green Lantern" headlamp is now perfected. I bought a cheap clip on headlamp last night, gutted it and was able to mount the green LED and a regulated constant current source into the housing. I have a much narrower and intense beam now that it is focused.

Warning: technical talk for the electronics geeks:

The light output vs current follows a expidental curve, so once you get a little past the knee of the curve, the light output doesn't go up much with increasing current. I found there was not a whole lot of difference between using 240 ma vs 350 ma. So, I set the current for the lower value to increase battery life some. It takes at least 7 V to power it to full brightness with the linear current regulator I'm using (LM317 and 5.1 ohm resistor), so I'll use 9V and rechargeable batteries, which will have to be in a sperate battery pack. Eventually I may try to make a switch mode current regulator so a smaller battery pack can be used.

The LED I used is made by Knightbright and available from Mouser.com as part #604-AAD19090ZG10ZC-S

[superman]

The "Green Lantern" headlamp is now perfected. I bought a cheap clip on headlamp last night, gutted it and was able to mount the green LED and a regulated constant current source into the housing. I have a much narrower and intense beam now that it is focused.

Warning: technical talk for the electronics geeks:

The light output vs current follows a expidental curve, so once you get a little past the knee of the curve, the light output doesn't go up much with increasing current. I found there was not a whole lot of difference between using 240 ma vs 350 ma. So, I set the current for the lower value to increase battery life some. It takes at least 7 V to power it to full brightness with the linear current regulator I'm using (LM317 and 5.1 ohm resistor), so I'll use 9V and rechargeable batteries, which will have to be in a sperate battery pack. Eventually I may try to make a switch mode current regulator so a smaller battery pack can be used.

The LED I used is made by Knightbright and available from Mouser.com as part #604-AAD19090ZG10ZC-S

I'd like to see some pictures pictures.

[dmax]

We use the green for fishing all night out on the boat. It works great!

[take-a-knee]

Is it easier on your eyes then Red? I know red will keep your night vision intact.

It doesn't matter which color you use, as long as it is colored it will preserve some night vision. Army chopper pilots used to use blue because not all maps/charts were could be read with a red light. If the light. any light is too bright, you'll get some bilateral constriction of the pupils that lasts about five minutes or so, but the big gain in night vision is preserving a chemical called rhodopsin, which any colored light does to some degree. Exposed to white light washes this out for about a half hour.

[Mud__Bone]

I could be wrong but I believe brightness goes down the color scale, starting at green, then blue, yellow, orange, red. interesting ideas here. :D

[Snowleopard]

The human eye is most sensitive to green at a wavelength of 555nm. This LED has its dominant emission wavelength at 530 nm where the eye has 0.862 of the sensitivity of the eye's peak. That's pretty good. A deep red LED emits at wavelengths where the eye has 0.0041 of the eye's peak sensitivity so it seems really dim.
http://everything2.com/title/relative+spectral+sensitivity+of+the+human+eye