Hello all,
A question about fuses:
If a Quick Blow (glass type, 20mm) fuse is rated 250V 1A
can I use it to protect a 9v ni-mh battery as well, or
will it only blow if the voltage is 250 ?
It doesn't care about the voltage. It'll blow if something manages to
draw more than an amp (or close to it - fuses are pretty accurate, but I
doubt that one has ever been made that's *EXACT*) through it at anywhere
from a voltge that's barely measurable, on up through 250 volts (And
beyond, but read on) The 250 rating is all about "When this puppy blows,
there's gonna be an arc that we don't want hitting anything else - This
fuse is designed to soak up, contain, or otherwise safely handle the arc
that a 250 volt source would produce." Which means that for a 9 volt
application, the "anti-arc" capability is overkill. It won't do any
harm, but it's "wasted effort", in a manner of speaking. Particularly if
you can get a 1 amp, closer-to-9-volts fuse for lower cost. (Not that
the cost of the fuse means much in a one-off situation like yours, but
even a penny difference in the cost of a part can make a significant
difference when talking about a production run of
who-knows-how-many-million units)