LUXEON DOUBLE STAR

Fellow CPFer's,

I recently mounted 2 Luxeon Star's on a relatively large heat sink, and wired them in series. I powered them at 6.8 volts, using 8 AA batteries (12 volts), and a switching step-down regulator I put together using the LM2595 IC (supposedly can get 95% efficiency). I have to tell you the light being put out is very impressive. I am thinking I might like to put together a flashlight using 2 Luxeon Star's, with the optics. I would probably wire the Luxeons in parallel at 3.2 volts, and use either 4 AA's, or 8 AA's. The current draw would be about 700mA, about the same as a 2 'D' cell incandescent flashlight. However, the quality of light thrown is much better, although maybe not a beam that will throw as far. With 8 AA's starting at 12 volts and dropping down to 3.2, the batteries would be completely expended. If rechargables were used, the 12 volt to 6,8 volt configuration could be used.


Any thoughts on this flashlight configuration. I am thinking to call it the 'Luxeon Double Star'. ?? Perhaps there could also be a 'Luxeon Triple Star', using 4 to 8 C batteries?

I used to think, Why bother with multiple Luxeons, when they will use equivalent current as an incandescent light bulb, but after seeing this high quality, extremely bright light, I really like it.

how about beam alignment? I was worried about whether they would be amalgamated into one beam with more than one LS.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by lightuser:
how about beam alignment? I was worried about whether they would be amalgamated into one beam with more than one LS.<HR></BLOCKQUOTE>

Lightuser,

Beam alignment is not a problem at all. The beams from the 2 Luxeons melt into one very bright and focused beam. Just the same as a single Luxeon, except twice as bright. I mounted them on a 2" X 3" X 1/4" piece of aluminum, which I plan to cut cooling fins, and add addtitional finned cooling plates to the back. I do not leave it on long at the moment, until I add more heat sink.

Sounds pretty interesting.
I'm just getting my first LS soon so
it will be a while before i can try two.
Definitely something i will be trying though.

Al

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by MrAl:
Sounds pretty interesting.
I'm just getting my first LS soon so
it will be a while before i can try two.
Definitely something i will be trying though.

Al<HR></BLOCKQUOTE>


MrAl,


Now I have been using this light quite a bit. I'm not sure how many hours I have on it. I didn't start with fresh batteries anyway. At first, the voltage out was a solid 3.4 volts. I am sorry I didn't measure the current. Now, with 8 volts in under load, the out voltage is only 3.2 to 3.3. I assume it is providing less current. I need to test this. I now have a .01 ohm resistor which I intend use to test current. (I still haven't really done a valid current test!?)

I am wondering if I should wire the Luxeons in series, and set the regulator at 6.8 volts. I am concerned about draining the batteries too low. And it also seems that there must be an internal resistance matter, when the batteries drop below a certain voltage?

By the way, for a while I have been working on getting the MAX756 on a one inch disc. I finally came up with a board design, and tonight I mounted the components, and it works. So now I have the MAX756 on a one inch disc! I also have a few MAX757 adjustables, which I plan on mounting on the one inch diameter board, but they will require 2 more resistors for the voltage setting. I am using the 150uF capacitor you guys just discovered at Mouser, and I am also using the same inductor, but I am using the 100uH inductor. Voltage with 2 volts in, provides just under 3.3 volts out. This will fit in several small flashlight projects I'm working on.

I do have some parts for the Zetex chip, but I just haven't started on that project yet. I've got too many irons in the fire now.