red LEDs, which is better?

[Illum]

In astronomy more than likely when you venture out with your Celestron, Meade, or Orion all you really need is a red headlamp and your done. Whenever we meet as a group though, someone will bring food, tables, sometimes if the weathers cold, there will be a campfire going in a drum:tinfoil:

I'm thinking of building a fixed table top red LED lamp that runs off 12VDC using a gooseneck with clamp and a metal enclosure big enough for me to mount heatsinks on top and recess the LEDs in to keep the glare down.

since they will be driven at very low currents, theres two main options for me [4 total]

5mm, in clusters of 10s driven at 5-15ma tops
or
Luxeon Stars, 6 at maximum, driven around 100-150ma tops


5mm comes in 630 and 660nm, I'm not sure which one is best to go for [630 = 20 degree viewing angle, 660 = 50 degrees, respectively]

Luxeon stars come in 625 and 617nm [red-orange] [Lambertian preferably, Viewing angle = 140 degrees]
I'll be buying at least one Lambertian to swap out a Dorcy Super 1 watt [cr123A version] for a red LED.

Anyone has preferences being outdoors at night?
PS: the reason why I'm ordering from the LEDsupply is because I also have some NW CREEs I have to order as well:)

 

[StarHalo]

The astronomy folk prefer 660nm LEDs, as they appear to preserve night vision better than the lower wavelengths. I have only minimal experience with this since the only 660nm LED I have is .025 lumens, but it certainly is a deeper shade of red.

The LED you linked to doesn't have the viewing angle listed, so I can't tell you how many lumens it is (if it's 20 deg, then that would be .2 lumens), you may need a whole lot of these to get anything more than a beacon-type light.

I know Roithner has a whole bunch of >630nm LEDs, including high-power multi-die units: http://www.roithner-laser.com/index.htm

 

[Seiko]

I made a red lantern using a luxIII. I tried the normal red in it and the red orange, I liked the red orange better then the red.

I bought a el chepo led lantern from walmart, and just popped my own driver, battery pack and led in. It had some sort of white 1watt lux in it before the swap.


Why do you want the 12V input? So you can hook it up to a car at the site? If thats not the case, why not just make things simple and run it off of a 18650? Much cheaper driver that way. And you could probably get off just running 1 led at 500 or 1000mA.

1400mA in the lantern is enough to light up a small 10'x15' cabin. Over an hour and a half of run time off a single 18650 too.

 

[baterija]

I didn't remember the ideal wavelength for best night vision preservation til just reading it here, but I remember the rule of thumb "redder is better." The red-orange is less than ideal. 660nm would be best as a color it's also showing lower lux which might make having "just enough" light easier to engineer.

 

[Illum]

Why do you want the 12V input? So you can hook it up to a car at the site? If thats not the case, why not just make things simple and run it off of a 18650? Much cheaper driver that way. And you could probably get off just running 1 led at 500 or 1000mA.

Well, in the club theres a few scopes whose tracker motor runs off of 12V, so by convention when we're going somewhere usually we lug jump starters and use them as battery packs...if someone needed AC theres inverters. Some with money may have bought themselves dedicated 12V battery packs but generally its 12V for everything we leave out. We had a 12V florescent light before with red filter paper over it...but it was way too bright for most tasks. :)

Plus we would set everything up around the evening and work with solar viewing until sunset...then we're usually out until midnight or later depending on what your hoping to see so runtime is going to have to be at least 5-7 hours...and I don't think 18650s has what it takes, but I certainly could be wrong:)

you'd be surprised how long a small 15AH jumpstarter lasts with these tiny tracking motors, I'm hoping to keep things below half an amp

theres my thoughts at the moment, excuse me on the poor drawings, I just finished dinner and spent a quick 5 minutes on it


yeah...a typo on this one...

 

[HarryN]

I have used the Lux III Red / orange (but not the red). There is a lot of light even at 200ma from just one of them.

I guess another path would be to use a driver and one Lux III.

4 or 5 in series with a resistor (perhaps variable) might do it as well.

 

[purduephotog]

LedEngin makes 660nm deep red LEDs. They come in 1, 5, 10, and (I think) 15watt packages.

The 10W I have- 4x of them- powered off of a 40W xitanium. I believe they are 11v at 1A or so (10W only specs).

They produce a significant amount of light (1.9W), have great thermal dissipation, glass domes.

I did ruin one of the devices by (probably) puncturing the resist with a multimeter probe. Because of the way the stars are designed it's not so easy to remove them and cutting all of the traces didn't help either- so I have a 25$ brick.

 

[Illum]

Sounds interesting, can you post a pic of these chips?

the Astrolite LED on a red filter supposedly peaks at 625nm...but I can't really find any info on it...and word by mouth isn't always accurate :candle:

 

[RyanA]

Radio shack has some 10mm 660nm leds, I've been playing around with a few lately.

 

[StarHalo]

Radio shack has some 10mm 660nm leds, I've been playing around with a few lately.

Those are the aforementioned .025 lumen LEDs I noted. I think they're too bright to use as a beacon and too dim to use as a flashlight, but I haven't used one in a reflector yet..

 

[RyanA]

I've been messing with them in Mini Mags, I'm going to try drilling out a reflector soon, but recently I've used one with the partial reflector from the nite-ize opalec knock off. It didn't make much of a difference. I think these have a pretty narrow viewing angle. Have you noticed that these make a sort of target shaped beam?:thinking: (and people still complain about cree rings) Maybe try sanding the led of cutting it to change the beam. I think maybe cutting it flat might even it out. But I can't think of a way to do it cleanly with the tools I have available. I've also tried the led in a solitare, but it's way to dim at 1.5v and at 3v it is quite a bit brighter than the red low on my RA twisty. I'm thinking about a resistor in the tailcap. Have you been able to get a current reading on this? The fuses in my ammeter are blown.

I cant seem to get a resistance reading either.