Hi,I'm late to the thread (as usual), but have looked at these LED's in the past. It was for a biotech imaging application. There are two types, a red/green/blue cluster or a blue / near UV LED with a white phosphor. These phosphors seem to have a fairly continuous spectrum, at least compared to fluorescent lamps and HID lamps. What surprised me was the speed. We had a strobe application for which a xenon strobe was proposed. I tried LED's (our optics "expert" said even normal LED's would not be fast enough). I knew normal LED's are fast enough but was unsure about the phosphor types. To my surprise they where faster than the xenon tube! They were faster than my detector. This has has an impact on the mill illumination in that you can get strobe effects that could cause you to think the spindle was stationary when it was not. This is more of a problem in a noisy environment than a home shop with only one machine running.  
Robert G8RPI.

--- On Sat, 30/1/10, J. Forster jfor@quik.com wrote:

From: J. Forster jfor@quik.com
Subject: Re: [time-nuts] Conducting Bench Top Material
To: "Magnus Danielson" magnus@rubidium.dyndns.org
Cc: "Discussion of precise time and frequency measurement" time-nuts@febo.com
Date: Saturday, 30 January, 2010, 1:15

To my aging eyes, the flashlight looks distinctly blue-white. I don't know
how these particular LEDs are built, but the unit is less than a year old.

-John

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The speed isn't  terribly surprising since the "phosphor" used  is
actually a scintillator.
Unlike phosphors scintillators don't have long decay times so there is
no afterglow like that from a phosphor.

The IKEA LED lamp output may not be significantly modulated if the wall
wart constant current supply may have an output thats a little smoother
than just rectified AC.

Bruce

Robert Atkinson wrote:

Yes, it is frustrating, they have to be the last dinosaurs of consumer
distribution.

For me, the nearest store is 6 hours away, if I don't get stopped for a
speeding ticket on the way...
So I can't afford to be interested in what they may have for sale.

Didier

Don Latham wrote:

Indeed.

Cheers,
Magnus

d.seiter@comcast.net wrote:

Sounds to me that the electronics died... rather than the bulb.

Cheers,
Magnus

Also they are very sensitive to heat, so do not use them in an enclosed
fixture.

I have been burned (figuratively) with these two gotchas, there may be more.
The one that lasts the longest in my house is the outside light at my back
door. It is turned on once a day around 6-7 PM and off in the morning, so
about 12 hours a day every day, and it lasts for years at that rate. Those
in the bathroom that get to be turned on and off several times a day for a
relatively short time don't do nearly as well.

Didier

Hi

At the cost target on those bulb's it's always a race to see who dies first.

The same can be said of conventional fluorescent fixtures. I have some big ones in the shop downstairs. The no name electronic ballasts that came with them all died in the first two years. I replaced them with name brand parts and they have run fine ever since (at least 3 years so far). All the fixtures are on their first set of bulbs.

Bob

On Jan 30, 2010, at 8:26 AM, Magnus Danielson wrote:

I bought some of the LED replacements for Edison bulb incandescents, and
they have an afterglow that lasts for several minutes.  It is very much
dimmer than when they are turned on, but is there none the less.

-Chuck

Bruce Griffiths wrote:

I have dissected many dead CFL's, and the key component failure
is the 10uf 350V electrolytic capacitor.  Most of these bulbs caution
against using them in a base up configuration.... which of course is
how most of my CFL's are operated.

I have several rooms that are lit exclusively with CFL's, and I find
that for best life, I have to leave them on all the time.  That is what
EPA has found too!  CFL's may take less power for a given illumination,
but the owners leave them on far longer than incandescent, and the net
result is greater power consumption overall.

Add that to the mandatory drop of mercury in each, and I really can't
see how they can sell them at all.

I got two for "free" from my power company (They hid the charge on my
bill, until the courts made them reverse it...) and included with the
CFL's was an elaborate procedure for cleaning up a broken CFL.  It involved
opening all of the windows, and leaving the room for a couple of hours,
and then, with a gloved hand putting the pieces on newspaper, and folding
the newspaper up and putting it in a 1 gallon zip lock baggie.  To clean up
the broken bits, you are supposed to vacuum the area with a fresh vacuum
cleaner bag, and then put the vacuum cleaner bag in a ziplock baggie, and
take the remains off to the hazardous waste disposal facility.

-Chuck Harris

Magnus Danielson wrote:

IKEA and $39 per lamp. Sounds like some pretty good margin in the sale.
I guess these LED things will be main stream and save the world when we see
them at walmart for $6.

On my bench I converted to 60 watt halogen lamps compared to the 100 watt
lamp.
Equivalent color spectrum to the traditional lamp also. For as many hours as
that light is on. I suspect I am saving some money in the long run.

Curious are these lights truly white or do they tend towards a traditional
lamp spectrum.
Regards

On Sat, Jan 30, 2010 at 8:15 AM, Didier Juges didier@cox.net wrote: