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Issue 7, March 2010 - LEDs - Page 1                                                                                  Previous Issues     
  

Let's drop in on Wily and look over his shoulder at his latest project....

High Power Flashing LED

Wily got an unusual request from a caller.  The company wanted to use an off-the-shelf solar powered LED path light but instead of a steady state light, they wanted the thing to flash.  The company did not want to go into detail about the ultimate application but they wanted the light to flash at a certain rate, a specific duration and be very bright.  The kicker was that instead of flashing a visible light, they wanted this device to flash invisible infrared light.  Wily suspected that the device was going to be used for some kind of military application but he didn’t push the company for more details.....
con't page 7

Wily Widget,
the Lone Inventor
 with Gadget & Gizmo

WHAT THE WORLD NEEDS NOW is a....  Long Lasting LED Night Light
I have tested a lot of fluorescent and LED type night lights over the years.  I have yet to find one, which is worth what I paid for it.  All of the fluorescent lamps died within a few months.  All LED lights faded to the 50% point in one year or less.  A 7 watt incandescent night light lamp does not put out much light and usually dies within 6 months but it is cheap and works the same predictable way from day one to when it dies.  I use a brighter 7 watt lamp in my laundry room, where it runs 24/7.  I use that position for testing the lifetime of various night lights.  There is a gray smudge above the power outlet in that room, left by the puffs of smoke that came out of many of the night lights I have tested over the years when they died.....
story con't on page 6

Fading White LEDs
By: Dave Johnson  
                    
There is a “dirty little secret” in the LED lighting industry.  You will not see much being written about this because the industry does not want to talk about it.  “White LEDs fade.”  Some LEDs from China fade very rapidly.  I have seen some devices where the light output drops by 50% in only a few weeks.  I cringe when I see those same devices being used in incandescent lamp replacement fixtures, nightlights and flashlights.....

  story con't on page 8

New Products 2009
New product announcements are made nearly every day.  I subscribe to many trade journals and each is filled with hundreds of flashy advertisements.  But, only a few of those product ads catch my eye.  Since I’m a circuit designer, I especially like those components that trigger many new application ideas in my mind.  Sometimes it is the smallest products that are the most useful.  I often discovered new products in surplus electronic catalogs.  The surplus companies often buy up stock that came from companies that went out of business.  Bad marketing or bad management may have killed a perfectly good product idea.  Their loss can be your gain if you can spot the bargain.                               
White LED Lifetime Tests
By: Dave Johnson

A dirty little secret in the lighting industry is that all white LEDs fade over time. I’ve been conducting some more experiments on some white LEDs offered on Ebay.  I have purchased many LEDs through eBay over the years but I have yet to find a quality white LED, made in China. I want to world to know that many of the so-called white LED bargains on Ebay are not bargains at all. ....
                                                                                                            

   story con't on page 4

Wrong LED Wavelength               

I got a call from a lighting company.  The company made custom overhead light assemblies, used mostly for hospitals.  One of the accessories the company offered with their lights was a hand held infrared remote.  The user could point the remote at a light receiver built into the toggle switch panel and control the lights. The company had been buying these simple remotes from the same company for many years without problems.....

 story con't on page 3

Another Bad LED Night Light

The wife bought me yet another LED night light to test.  She bought it at Walgreens.  This thing was fairly small.  As shown below, it was sold in a blister pack containing two lights.  The package claimed that the light would last 50,000 hours, which if used 24 hours each day would be 5.7 years.  Each light contained three wide angle white LEDs.  It was designed to screw into and replace a standard 4w incandescent lamp, using a miniature screw base.....


story con't on page 5    

 

March 2010     Issue 7

Page 1 Back
Envelope
Circuit
Diagnosis
Experimenter's
Corner
Good Idea
gone Badly
New Products Rants &
Raves
What the World
needs Now
Wily Widget


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