I have like 10+ different old chargers for mobile phones (nokia, SE, samsung,..), which are now useless, because there is still no standard connector for charging mobile phones.
So to make use of them, I was thinking that those chargers could be ok powering leds of 220V. Output voltage is about 5V - which is a little high for leds (but maybe it could be ok?), current of chargers is around 0,5A. Any idea if this would work ok in DD for some home indirect lightening? Also Cree q5 can be found cheap on ebay...
A few issues you might encounter or in native language: Da ne boš zajebal...
Many high power leds like around 3,5V voltage. Also they dislike very high current. Putting 2A on a Q5 is also not a good idea. You need to use some series of diodes to drop the voltage to sutable level and a resistor (a few watt resisitor not those 1/4W commonly available) to limit the current through the led. A dedicated regulator is much more preferred than those A.C.M.E. halfassed jobs.
Personally ill rather buy a already made 23'0V to led driver/transformer/regulator instead. DX carry something like that i believe undther the flashlight DIY section. Be sure you take care as i want no complaints as for burning down the house. :)
Last but not least, you'll need a form of heatsinking for those led emitters. Just putting a few wires on their board won't do. Running them loose at 3,7V@1,2A might be their premature death in minutes!
An lastly you should also think about a reflector if you don't want a emitter type dependant diffused light source.
Just for fun! I tried a nokia charger rated 3,7V and 350mA wired on this http://www.manafont.com/product_info.php/3meter-30led-whitecolor-holiday-string-lights-3xaa-battery-p-77 amd after a min it started to smoke and smell bad.
I thought something close to 4,5V @ 50mA would be perfect. Well 3,7 @350mA was not good. :P
You'll probably want a driver for any led unless you have exactly the right voltage. Since you need a heatsink/components to drop voltage, you might as well just buy a cheap buck driver. DX sells an empty light bulb with pill for LED and driver:
I got a couple of mini to micro 3" adaptors from Meritline real cheap so I could still use some of my older chargers. May be an option unless you have a smart phone and they don't put out enough current.