[sci.electronics] Why do the rest stay on when one goes out?

amstein@pixar.UUCP (Peter Amstein) (12/23/89)

Those small Christmas lights that are quite common are (typically 35 or 50)
series connected low-voltage bulbs.  They still claim that when one goes
out, the rest stay lit - and usually it works.  Does anyone know how this
works?  What's in each of those little bulbs that makes it conduct after
the filament goes?  A resistor connected in parallel with the filament maybe?
Some elfen magic from Santa's workshop?

Peter Amstein
{ucbvax,sun}!pixar!amstein

mmm@cup.portal.com (Mark Robert Thorson) (12/24/89)

Look very carefully at the bulb.  Below the filament, just above the glass
bead, there should some fine wire wrapped around the wires which hold the
filament.  That's where the electricity is conducted.

Considering how the entire chain of lights should be considered hot, I'm
surprised I've never heard of anyone getting electrocuted from these things.
It seems like a setup for disaster:  cheaply-made hot lights and aluminized
tinsel.  If one finger of the tinsel reaches inside a bulb holder, the
whole tree becomes hot.