Heatsinks, optics, etc...

i have been tinkering for a week with some ls 1w.

i got some hd's from arc to toy with. i also cannabalized my Reactor to get the ls and optics.
yup, had to chop it open with the dremel cutter!

currently, i have the reactor ls with optics running on 4 D cells--nearly direct drive. i used a 25 ohm variable resistor, so i could gently bump up the drive. (FYI, i tried a maglite reflector with the HD's, but the pattern was poor--it was only a quick test.)

well, on the lowest resistance setting, i get approx. 0.3 ohms, and find it drawing well over 500 milliamps. i have a cheap 500mA meter, which is pegged!

just what is the limit anyway?
do i need a better multimeter to measure current? i just need a ballpark to figure out runtime...

i was concerned about heat, so i have it mounted on a large CPU finned heatsink with a 12v fan.

it works well! i had it on for about 20 minutes last night. first at 4.5v, then at 6v.

i can detect no heat by hand--but i dont have a thermometer to measure. and, it puts out a LOT of light. i can light up my neighbor's shed, which is about 60 feet from my back door. and with the CMG optic, the beam pattern is excellent.

anybody try heatsinking like this?

also, i have the 2 arc ls hd's mounted on smaller heatsinks with fans. these are running with resistors right at spec of 350mA (i set it up this way just for testing). these LED's are much whiter than the CMG ls, which has that green corona.

next: try the arc hd direct drive or overdriven with the cmg optic--should make for an excellent quality of light.

then: try the LS/o for comparison to the CMG optics with the arc LS LED. i wonder which will have the better pattern (not too compact, not too wide, with good throw).
im about to order some right now.

any thoughts?

Bob<--nuts.

Originally posted by pedalinbob:
...also, i have the 2 arc ls hd's mounted on smaller heatsinks with fans. these are running with resistors right at spec of 350mA (i set it up this way just for testing). these LED's are much whiter than the CMG ls, which has that green corona...

...then: try the LS/o for comparison to the CMG optics with the arc LS LED. i wonder which will have the better pattern (not too compact, not too wide, with good throw).
im about to order some right now.

any thoughts?

Bob<--nuts.

Click to expand...

<font size="2" face="Verdana, Arial">Bob,

Your heatsinking sounds like overkill. You shouldn't need a fan to run an LS at 350ma. Concerns about heat are good, but 350ma is the appropriate spec to run a white LS at without an extra heatsink or fan, if it's in open air.

Also, if you're looking for more throw, I personally recommend the side emitters along with your choice of reflector. They also give a wider cone of spill light. i.e they make for a typical flashlight beam, as opposed to the wide central beam with no spill, characteristic of the LS/o.

yeah, i know the fans are overkill--i just didnt want to fry the ls's.

the one ls is way overdriven, and i figure the giant heatsink and fan wont hurt.

YES, i am very interested in the side emitters, since i hear that some have had good luck using them with mag reflectors.

just ordered a couple of ls/o, so i will try them first, then later try the se's.

thanks for the info!

Bob