Looks familiar…

http://www.thinkgeek.com/gadgets/lights/831e/

Nine bucks more and you get a five watt LED..

Posted at 10:08 am on Sep 20th, 2009 by Bill Hates

yes, yes, but this is HACKaday.

excellent hack as always from sprite_tm

Posted at 10:15 am on Sep 20th, 2009 by jomegat

Nice work!

Honestly, even with the wires and circuit board hanging out it’s more attractive than the thinkgeek bulb. ;)

Posted at 10:35 am on Sep 20th, 2009 by hpux735

I did something similar after seeing the one on thinkgeek.

Posted at 10:35 am on Sep 20th, 2009 by thedudefrommiamivice

why is there no heatsink ? besides this its nice.

Posted at 11:42 am on Sep 20th, 2009 by just some nerd

i have to agree, sprite_tm never fails to deliver good hacks.

Posted at 12:19 pm on Sep 20th, 2009 by andrew

Ok, it’s a nice design but he could have done this less complicated with only one buck converter for the 3 leds and 1 transistor per led for pwm.
Simpler, cheaper, better efficiency and way less noisier.

Anyway, for a first, it’s quite good.

Posted at 2:16 pm on Sep 20th, 2009 by ino

Ino: I tried that… but unfortunately all the components had such losses that I couldn’t reach the needed 1amp to light the leds fully at 1/3th duty cycle. That’s why I took this approach.

Posted at 1:50 am on Sep 21st, 2009 by Sprite_tm

Oh, to add to my previous post: why the 1/3th duty cycle? Because the leds have a different forward voltage, which means I still would have to use series resistors if I wanted to turn them all on at the same time. By switching them on one at a time, I could use the buck-converter to adjust for the difference.

Posted at 1:52 am on Sep 21st, 2009 by Sprite_tm

Oh ok, I see. Buck converters aren’t easy to design when you’re looking for efficiency.

You should check on Dx, there’s a converter delivering 650mA under 3.6V. It’s almost perfect for this kind of application and around 3 bucks.

Posted at 3:19 am on Sep 21st, 2009 by ino

Just wondering- didnt he break open a cfl which contains a small amount of mercury?

Posted at 8:01 am on Sep 21st, 2009 by ctabm

My guess is he removed the ” tube ” from the pcb. No need to break it.

Posted at 10:16 am on Sep 21st, 2009 by ino

Nope. The internals of the lamp still are intact; I could put 220V on it and have some light if I wanted.

Posted at 10:24 am on Sep 21st, 2009 by Sprite_tm

just giving you a hard time sprite…. I like the hack!

Posted at 9:18 pm on Sep 21st, 2009 by Bill Hates

Bulbs…? Don’t they grow out of the ground….Oh you mean a lamp! lol

Posted at 5:07 am on Sep 22nd, 2009 by Jack