A few quick questions

[StoneDog]

Hi all.

I keep a little Ray-o-vac 2AA in my car to help find things at night, read maps, etc. It's the swivel-head light w/ plastic spring loaded clip from their Sportsman line.

Anyway, I REALLY want to put either a single LS or an array of 5mm or even 3mm LEDs in there, possibly driven by a MicroPuck. My goal is a nice, smooth and very useable flood good for at least 5 feet but that isn't too bright to blind someone that's using it to read a map.

So right now my options are a 1w LS HD w/ no reflector, an array of 5mm White or Yellow Nichias, a bigger array of 3mm arrays (only because I can pack more into the light).

I'd like to ask the experts a few questions though:

1) If a 1w Luxeon Star (with Star board underneath it) is driven at spec will it require additional heat sinking?

2) Could 2 Lithium AA's drive an amber or red LS w/o a MicroPuck.

3) Do the 3mm LED's have different Vin or current requirements than the 5mm?

Thanks,

Jon

 

[OddOne]

1. Yes.

2. Yes, although with a lower usable life as the output will fall off as the batteries drain. Using a driver like a Micropuck or a ZLT board will keep the output more even for a longer period, even as the battery output falls below what'd be usable in a direct-drive situation.

3. Vfwd and Ifwd usually differs slightly from LED to LED of the same type. Usually, if the various products of a particular LED line all use the same LED die they'll be within a narrow range of each other even if the packages differ, but from mfr. to mfr. the differences can be pronounced. LEDs tend to have "universal" ranges based on color though - most white LEDs want 3.4-3.6VDC @ 30mA regardless of package (with the exception of high-power LEDs like Luxeons, etc.).

Hope that helps somewhat. /ubbthreads/images/graemlins/grin.gif

oO

 

[Ben H]

I'd recommend a red/orange LS star and some alkalines. I put one in a aluminum colemann 2AA flashlight and with fresh batteries it is super bright. You might want it a bit dimmer, so you could use a resistor or some slighy used batteries. If you underdrive it you shouldn't have to worry about heat too much.

 

[StoneDog]

hmmm... maybe a 5mm or 3mm array is a better idea then. There's very little room to get additional Al or Cu in the head... If I could find a way to fit 14 Nichias in there they'd each be driven at ~25ma. I don't think they would require any signicant heat sinking...

Jon