Sunday, November 2, 2008

High-speed video LED lighting tests

One of the important supporting projects I have been working on is developing a better light source for the Exilim EX-F1 camera.  As you may recall, on our first flight, we depended on getting light from a cabin window, but this placed a lot of restrictions on freedom of movement, which is important because if you are strapped down, your apparatus isn't always in microgravity; it depends on how good the pilot is at flying the parabola.  If you are freely floating, on the other hand, any variations just cause everything to wobble together, so other than some minor effects due to friction with the air, everything will be very close to zero-g as long as you don't hit a wall, and nobody hits you!

Therefore my plan is to build a portable light source for the camera.  Typical video camera lighting systems start at over $100 for a 10watt halogen system, so I figured it would be more fun to build my own using multiple 3watt luxeon white LEDs from SparkFun (they also have some nice heatsinks for these nasty little critters).

Here's some video of the first test runs, which are very encouraging.  I soldered up 8 3watt LEDs to heatsinks, put them on a styrofoam ring, and wired them up in parallel to 3 1.2v NiMH cells (so I'm actually undervolting them a bit).  You have to use NiMH or NiCd for this kind of application because non-rechargable cells just can't source the current needed - probably 5 or 6 amps total.

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