by Don_HH2K » Sun 24 May, 2009 12:24 am
I built a 12-LED flashlight today out of an old Union Carbide flashlight and a failed LED light bulb. It turns out that the 18 LEDs in the bulb were all wired in series and only one had shot out, so I removed the other 17 and tried to do something else with them.
(No, that's not backwards - I broke the switch.)
The LEDs are mounted on two pieces of PVC, with wires soldered in place on the backside. Each one dissipates 20mA of current at 3 volts, and they're all in parallel, so technically the "bulb" is rated for 0.72 watts. A typical flashlight bulb runs between two and four watts, so this is pretty cool - and it's powered by two D-cells, so it'll last awhile.
That's the best image I could get that adequately showed the brightness of the beam; sorry that I don't have a tripod to keep the camera steady for slow exposures.
UserAgent: Mozilla/5.0 (Windows; U; Windows NT 6.1 x64; en-US; rv:1.9.2a1pre) Gecko/20090510 Minefield/3.6a1pre (.NET CLR 3.5.30729)
Laptop: HP Compaq nx6325 - Turion 64 X2 @ 2GHz, 2GB DDR2, 100GB HD, ATI Radeon X300, 15" LCD, Seven Pro
Handheld: Palm Treo 650 - Intel PXA270 @ 312MHz, 10MB RAM, 32MB flash, 2.7" LCD, Palm OS 5.4