Free Republic
Browse · Search
News/Activism
Topics · Post Article

To: Tarpon
My little Rayovac is, IIRC, rated at 80 Lumens. We also have a 3/C Rayovac, which is rated at 4W, using a Cree LED, it is if I remember the label, a 150 Lumen flashlight. It is brutally bright -- much moreso than my penlight, which is itself no slouch (it makes a stock Mini-Maglite look like a birthday candle).

BTW, the Rayovacs (OEM'd by another outfit that sells to various other marketeeers) are the dirty little secret of the white LED flashlight world. They dollar for dollar the best thing going. Our two lights cost approx. $25 each, which is absurdly low for the kind of performance they deliver.

That said, neither of these LEDs are impressive at all when operated sans reflector. That light is amazing when focussed in a tight beam, but when spread out according to the inverse square law, it's visual evidence that current LED tech just ain't even close to prime time insofar as general room illumination applications are concerned.

For anything that needs spot illumination (i.e., over the stove, or tracklighting aimed at pictures on the wall) they'd do great -- but for lighting up the room, nope, not even close.

WRT traffic lights and headlights, it's the same scenario. In the first case, you're looking AT the LED(s). Even a 30ma 5MM LED can be seen at a great distance -- when you're looking AT the device. In the case of headlights, we're back to aimed/focussed/beamed light, in which the LEDs do excel. But neither of those applications acquit the LED as a viable room light.

One last comment, regarding the "100,000 hour lifespan" -- that's a big adspeekish, because LEDs are rated according to something like a halflife projection. Unlike most semiconductors, which are essentially "forever" devices (excepting defective units which suffer "infant death" in the first few hours of operation, and, unless subjected to abuse in the form of excessive voltage, current, or heat), the "Power LED" is not "permanent" (unless operated significantly below rated output).

At the 100,000 hour point, the device will still be tossing out light, but it'll be a LOT less light than when it was new.

136 posted on 12/18/2007 7:50:45 AM PST by Don Joe (We've traded the Rule of Law for the Law of Rule.)
[ Post Reply | Private Reply | To 133 | View Replies ]


To: Don Joe
The first CREE LEDs are throwers, now they are concentrating on flood. Here is a Chinese goods site that has some of the new lights showing up almost weekly. Mostly array, but others are coming. Right now they are expensive, $50 for a 40 watt bulb is steep. I have an array light that I use for car repairs, it's a battery powered array light. Works great without the cord.

The phosphor coatings are getting a lot of play, especially in back-lighting of LCD screens. The technology is moving fast now, who knows what the next few years will bring. I have a project to use strip LED lights under the cabinets in the kitchen, the wife thinks it’s cool the way they light up the counter/floor/room with no heat. Heck all you need is a light sensor and leave them on all the time :-) -- May even run them on rechargeable AA batteries.

I don’t think reflectors are the way to go with LEDs, optics is where it’s at IMHO. With optics you can tailor the beam, a desk lamp is one application that fits, wall sconces and other area lighting applications are more likely first applications. I think in the not to distant future the LED 'bulbs' will be built in to the wall, roof or cabinet. Open the door to the cabinet and the LED comes on, provides a task light to see what is in the cabinet or even closets.

139 posted on 12/18/2007 2:02:22 PM PST by Tarpon
[ Post Reply | Private Reply | To 136 | View Replies ]

Free Republic
Browse · Search
News/Activism
Topics · Post Article


FreeRepublic, LLC, PO BOX 9771, FRESNO, CA 93794
FreeRepublic.com is powered by software copyright 2000-2008 John Robinson