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Seventeen milliwatts
A blue LED, dropping 2.88V and consuming 5.93 milliamps, throws a visible circle of light a metre wide onto a ceiling two metres above it, and you get little spots in your eyes if you look directly at it.
This surprises me somewhat, particularly since I know the eye isn't all that efficient in the blue (I don't have a data-sheet for the LED, it came from ultraleds.co.uk and possibly their market is more "ooh, shiny blue thing to put on my tyre-rims" than the quantum fan, but hc/Ve gives 430nm); especially since the LED is specced to run up to 20mA power consumption.
I have a green one that consumes 5.27mA over 3.2V and lights the ceiling more brightly, though in a smaller circle; the red, 2.1V and something like 63mA, are a much brighter light. Also some infra-red LEDs, 11mA at 1.16V; obviously you can't see them lighting the ceiling, though I have a webcam that can detect them (to my slight surprise they appear white, so the colour filters on the webcam's CMOS must be uniformly transparent in the IR) -- but the webcam can't see the reflection on the ceiling, and I'm not sure if this is because the light is faint or the webcam sensor poor. And even a few UV LEDs, though I feel uneasy plugging them in (I don't have any obvious test for UV, and even 375nm light is not great for the eyes), so haven't.
Not quite sure why I picked now, rather than say fifteen years ago, to get interested in electronics again; I suppose I'm a bit less clumsy, significantly less prone to blowing components up to see the flash, and I feel more able to afford the components and the test equipment (though a multimeter nowadays costs £2.99). My vague hope is, with sixteen NAND gates, half a dozen 555 oscillators and a dozen LEDs of different bright primary colours, to be able to build an entertainingly flashy Christmas ornament -- though I probably don't have the craft skills to build a nice box to put it in.
This surprises me somewhat, particularly since I know the eye isn't all that efficient in the blue (I don't have a data-sheet for the LED, it came from ultraleds.co.uk and possibly their market is more "ooh, shiny blue thing to put on my tyre-rims" than the quantum fan, but hc/Ve gives 430nm); especially since the LED is specced to run up to 20mA power consumption.
I have a green one that consumes 5.27mA over 3.2V and lights the ceiling more brightly, though in a smaller circle; the red, 2.1V and something like 63mA, are a much brighter light. Also some infra-red LEDs, 11mA at 1.16V; obviously you can't see them lighting the ceiling, though I have a webcam that can detect them (to my slight surprise they appear white, so the colour filters on the webcam's CMOS must be uniformly transparent in the IR) -- but the webcam can't see the reflection on the ceiling, and I'm not sure if this is because the light is faint or the webcam sensor poor. And even a few UV LEDs, though I feel uneasy plugging them in (I don't have any obvious test for UV, and even 375nm light is not great for the eyes), so haven't.
Not quite sure why I picked now, rather than say fifteen years ago, to get interested in electronics again; I suppose I'm a bit less clumsy, significantly less prone to blowing components up to see the flash, and I feel more able to afford the components and the test equipment (though a multimeter nowadays costs £2.99). My vague hope is, with sixteen NAND gates, half a dozen 555 oscillators and a dozen LEDs of different bright primary colours, to be able to build an entertainingly flashy Christmas ornament -- though I probably don't have the craft skills to build a nice box to put it in.
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http://members.misty.com/don/index.html
http://ledmuseum.home.att.net/
http://www.equipped.org/led_lights.htm
where there is a lot of information on LEDs.
For the UV LEDs, use a bit of fluorescent plastic or a new T-shirt, the optical brighteners fluoresce blue-white.
Something else that may interest you is the line of Toshiba Constant Current LED Drivers. These can help prevent blowing up the newer LEDs, which are not forgiving of overvoltage and overcurrent conditions.
http://www.marktechopto.com/catalog.cfm?Drill_Level=Series&DeptID=2100&SeriesID=1286
If you were to set up a shift register IC as a pseudo random number generator, and drove one of the Toshiba drivers you'd get a nice blinky light device with a lot fewer ICs.
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Do you have anything in the way of large expanses of white fabric? Say, a sheet?
There's something in most commercial laundry detergents / brighteners that fluoresces very nicely. You've probably seen the effect on TV any number of times - someone's T-shirt glowing a nice bright barely-blue white? My white sheets do the same thing, as do all my other whites - t-shirts, dress shirts, socks, etc. ad nauseum.
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You have a webcam that does IR?! *boggle* *giggle*