Another fluorescent nightlight dissected

http://picasaweb.google.com/lh/photo/vZDkQ8cEjsiEV6QAyGspMQ?feat=directlink
This cute little First Alert nightlight someone gave me a while back
lasted all of 6 hours before it failed. The lamp is a small U-shaped hot cathode fluorescent made of tubing roughly 11mm diameter. R3 was burned beyond recognition but measured around 32K which may or may not be close to its original value and both cathodes in the lamp are open. All resistors are 1/4W except for R2 which appears to be a 1/2W fusible type.
D1, D2, C1, and C2 form a half wave bridge voltage doubler. R1 and R5 discharge the capacitors when the unit is unplugged. R2 serves as the ballast, limiting current in the tube, while R3 and R4 provide current to heat the cathodes. Running the tube from DC can't be good for it under the best of circumstances but I would hope these typically last longer than this one did.
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On Wed, 22 Apr 2009 22:14:16 -0700, James Sweet

Just another electro-greenless dope looking for yet another meaningless way to dump electrons through wires?
If you don't have kids, you don't need a night light. Even with kids, it can be argued against.
Carry an LED flashlight around that you keep by your bedside, or simply with you in your dark house at night. They do not consume much, and you can get the lever charging type.
Even a monkey knows how to familiarize himself with his local domain... even in the dark.
Also, learning how to walk blindly in known surroundings exercises the brain, and you learn a skill as well.
It also adds safety, as in if there is a fire, the smoke makes it pitch black, even with a night light, so the skill of 'knowing' one's floor layout is actually an essential safety measure.
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There's those mysterious diodes again.
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Rich. wrote:

What's mysterious about them? The purpose is obvious in this circuit, the diodes are part of a voltage doubler.
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I am Curly Gouger Watts (The Anal Man) & I come from down your way.
Kirk Johnson "Anal Stretching Specialist" http://www.imagefap.com/image.php?id 88478267
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now you know why someone gave it to you
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