Does anybody know if the strings are supposed to stay lit if one goes out? I realize each LED has a huge life, but the contacts could fail. Thanks. Before I make the investment I want to know what I am getting into, because that it why I have never used mini-lights. Frank
I don't know how old you are, but the "old-fashioned" kind that I think of were wired in series and when one went out, they all went out. They were a real PITA if you happened to have two bad bulbs in one string.
On most I've used, they all go out. However, I've got an exception here. It's one of the 70-LED strings from Lowe's. About 10 LEDs have gone out (some in each half of the string). The others are just as bright.
That's not exactly true. I've yet to see one that failed anything but open
- circuit broken. If they are connected in series, and the cheapest ones are, they will fail the corresponding section of the string just like the regular lights. If you can find a 12V outdoor one, where diodes are connected in parallel, one bad one will not bring the whole string down. That said, I've yet to come across a 12V LED lights that were intended for outdoors ...
The ones I've used seem to have resistors in the sockets, which would carry the load if a diode quit. And, in the multi color strings, the resistors seem to vary in value depending on the color; some colors require more current than others to give the same light output appearance. I don't think every color has resistors, but I don't remember as I checked several years ago.
Also, because the strings which I have blink, due to the half cycle on and half cycle off (they are 1/2 wave rectifiers), I've added a full wave rectifier to the plug end. I know that stresses the individual diodes as there is twice as much power dissipation, but no problems after about 5 years. The full wave rectifier also makes them a little brighter.
The most common "initial" failure of a diode is to fail to a low impedence - or a short - which in many circuits leads to high amperage which then blows the diode to open. In a series string environment, a "low impedence" failure does not result in destructive high currents, so MANY times, a series connected diode can fail "shorted" and the rest of the (light emitting) diodes in the string will continue to light.
White LEDs have traditionally been blue inside with a phosphor that, when excited, glows cool white. What I don't like about the white LEDs is that they don't seem to hold up for a long time; they turn dim and sort of, blue. Now, this year I've noticed "warm white" LEDs in the Christmas decorations. To me they still don't look like traditional clear lamps. They have a sort of greenish-yellow color. And different strings seem to look different in color. Maybe in a few years they will perfect the warm white thing, or .... we will learn to get used to it.
I have a couple strings of "color changing" LED lights. They change between blue, violet, white, and yellow. They bight be using blue and yellow LEDs using opposite polarity.
Know what you mean though, it's not quite the same. But then for Christmas lights they're not for illuminating the entire room, so I don't think the not-quite-what-we're-used-to light output is much of an issue. (I spent about an hour last night making three good strings of incandescent lights from four, so anything that's more reliable gets my vote)
I don't know, I seem to remember a few decades ago connecting LEDs directly across 9V batteries to see how far across the room I could get the fragments to fly when they exploded. I think it's possible for folk to amuse themselves in destroying pretty much anything :-)
(the bulb story's funny, though - triggered a memory of me aged ten or so being allowed to wrap failed incandescents up in newspaper and then smack them with a big hammer, just for the nice popping sound they made as they broke!)
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