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What the World Needs Now -- Long Lasting LED Night Light                                 
  

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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.
7W Incandescent Night Light Bulb   Plug Mounted LED Night Light
What I would like to see is a quality light.  I don’t mind paying more money for it but I want it to work more than a year, 5 years would be better.  I imagine a white LED light, which might draw about 2 watts of power and emits a reasonable amount of light.  A light, which emits a bit more than a 7 watt incandescent lamp would be about right.  It needs to use good heat management techniques, so the LED device will last several years before it hits the 50%

intensity point.  I think a reasonable figure of 5 years is doable.  An automatic day/night switch would be nice, so the thing would not be turned on needlessly in the daylight.  Am I asking too much?  I can’t imagine that the electronics inside one of these things would be more complex than a compact fluorescent lamp. Why can’t someone make such a thing?

Perhaps one way to handle the heat from the LED and the drive circuit is to use a liquid.   Mineral oil or a phase change wax should do a fine job in drawing away the heat from internal parts toward the outside, where it can efficiently be dissipated.  An example of such a light is shown below from a company called “Eternal LED.”  Perhaps their “Hyralux” device could be scaled down for a night light application.

“Eternal LED” Liquid Cooled LED Light  

I would think that a single efficient power LED would work better than a large cluster of smaller devices.  This type of device would also be easier to keep cool.  It would require a compact AC to DC converter, which would supply the LED with a constant current.  The are lots of well designed AC to DC power supply circuits which could be modified for driving a 1 or 2 watt white LED with a constant current.  Bias Power makes one such module but it only produces a fixed voltage.  But, it would work for a couple 1W white LEDs as shown below.  The Bias modules are pretty small so they could be slipped into a plastic housing with ease.

    Tiny BIAS Power Supply
 


March 2010     Issue 7

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Envelope
Circuit
Diagnosis
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Good Idea
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New Products Rants &
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What the World
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