Long ago they figured out how to keep a string of lights going even as the bulbs fail, and keep people from just pulling the blown bulbs out. Let me take a closer look at these unique bulbs, and you can decide how they did it.
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Try using the edge of the file to open the bulb. Hold the bulb with a work glove, hold the edge of the file to the glass at a steep angle. We used that method in school when we studied filaments.
We have pretty much converted all our Christmas lights to LED. But I've always found the incandescent burnt bulb shunt pretty clever. Having said that I don't miss the pre-Christmas light string troubleshooting when the shunt does not work,
Ever wondered why these are called fairy lights?
In 1881 Joseph Swan (English inventor of the light bulb) illuminated the Savoy Theatre in London using only electricity (no motor limelight). The following year he was asked to provide lights that the actors could wear whilst playing the role of fairies. The next day the press reporters described them as Fairy Lights.
Same way as we got the expression ‘happy as Larry’
It the wire has a very thin insulating oxide on it so that when the bulb is intact only 6v or so us across it and the insulation works, but when the filament opens up, the thin oxide layer punches through because 120v is across it. There isn't much resistance, the load to the rest of the bulbs DOES increase and they DO over voltage and blow out if you allow to many bad bulbs to remain in the cbain.
Please explain why there are 3 wires in stead of 2.
From what I know they have a thin oxide film that breakd down when a bulb fails since it gets full mains on it for a short duration which makes it short.
So for every bulb that goes the others are getting a bit higher voltage each time.
I think that if you manage to remove the glass of a working bulb you'll find that the filament is under tension. At burn out, the the arms return to a relaxed position, || becomes \|. The coil of resistive wire makes contact due to the spring action of the filament arm. This is probably a fail closed switch.
EEVblog multimeter🤩
The filament seems to be too delicate to withstand any force, so any spring action would just stretch the filament out immediately.
Ya the shunting device has a coating on the wire that increases its resistance. When the bulb blows the coating on the wire melts enough it lowers the resistance of the wire and the electricity now flows through it keeping the rest of the string lit. When I was a little boy mini lights or midget lites back then did not have this extra wire at the base and the whole string would go out. It was a pain to then figure out which bulb was the blown one haha
A pair of needle nosed vice grips would break a bulb like that without destroying the insides.
Very Interesting Fran.
The wrapped wire has a very thin iinsulating coating on it. When the filament opens, the full line voltage appears temporarily across the blown bulb, causes the insulation to break down, and the wire to short between the 2 support rods.
My understanding is that the shunt wire is just plain aluminum that was heated to thicken its oxide layer, and is only loosely wound in place. In normal operation with a working filament conducting the current, the shunt wire does not pass any current. Once the filament breaks, however, the full line voltage present is enough to conduct through that layer, and the resulting heat generated welds the wire in place. This is why they're sometimes finicky, as they can break free again.
ps merry christmas, Fran, and may your new year be a blessed one
Lol electricity still seems like magic to me. 😂
Why can't you say "Christmas"?
I have no clue… but I know for a fact someone here does. I think its facinating none the less.