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Re: Fuses



Try using a thin strip of tinfoil for your fuse. In the old days of
paper capacitors, we used to take a .02 uF capacitor apart and
cut up the foil into strips. One caution though.... cover the apparatus
with clear plate glass or plastic for safety purposes. When the
fuse blows, small pieces of hot metal sometimes shoot out of it.


On Thu, 11 Mar 1999 16:10:12 -0500 GARY HEMMINGER
<Hemmig@D-E.PVT.K12.NJ.US> writes:
In order to reinforce the understanding of current in circuits I like
to have
kids build a circuit in which there is a homemade fuse, and
then instruct them to keep adding more bulbs in parallel. It's nice
to have a fuse that fails with some drama, but the best I've come up
with is a piece of iron from a steel wool pad. Before failure these
often glow somewhat, but they also seem to have the undesirable
property of an increasingly high resistance as more bulbs are added,
thus even with a suitable power supply rather than batteries, the
bulbs dim each time another is added and I must wave my
hands about the fact that in your living room this doesn't happen.
I'm curious to know if anyone has a suggestion for a better material,
and also, if anyone can comment on what is actually used in real
fuses. Obviously the melting point has to be right, but from what I
see in this circuit, a real fuse must also have a low
resistance.

*****************************************
Gary Hemminger
Dwight-Engelwood School
315 E. Palisade Ave.
Englewood, New Jersey
07631
e-mail: hemmig@d-e.pvt.k12.nj.us
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