Christmas LEDs REvisited

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en'til Zog
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Joined: Fri Jul 12, 2002 3:03 pm
Location: The Wilds of Northwoods Wisconsin

Christmas LEDs REvisited

Post by en'til Zog » Tue Jul 18, 2006 11:02 pm

I've had a string of ForeverBright LED holiday lights up and glowing for 7 or 8 months continuous, now. When I put the string up, one LED 'burned out' quite promptly. I thought.

The one that was dark for months is now lit. But other LEDs are going out, and later coming back on.

Huh?

Ah, wait! These LEDs have a little circuit in the base wired in PARALLEL with the LED. These are meant to keep a string of BULBS lit, if one burns out.

LEDs are NOT bulbs. They're active semiconductors.

I figure that the 'keep the string lit' chip can't quite tell if the LED is working or not, so it occasionally conducts to 'keep the string lit'. Except that the LED isn't burned out - it's just being a semiconductor. That would account for the extremely slow flashing of the LEDs, and for the differing intensities they show at different times.

LED strings probably do NOT need a 'keep the string lit' device in each LED base. Amd it's probable that all the returned strings the company has gotten back do NOT have 'burned out' LEDs. Just overly entheusiastic "Keep 'em Glowing' chips.

FYI :?

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