[ Tom Lear wrote in 050126 MMDigest:


>> What a cool idea about recycling the carbon rod from a C cell
>> battery!  I always have a can of used batteries I'm saving for the
>> recycling center, so that may be a good source for a carbon rod in
>> a pinch.


I'm afraid that flashlight batteries are now constructed differently:
the carbon is on the outside and the zinc is on the inside, so there
is no carbon rod inside.  It is mourned by hobbyists of all persuasions.

One source of carbon is your local welding-supply shop.  They sell
rods for carbon-arc torches.  My dealer called them 'gouging rods.'
They are plated with copper for good electrical contact, which may or
may not be helpful, and are available in diameters up to 1/2", I think.
I paid US$1.50 each for mine several years ago.

The carbon in motor brushes is often doped with various sorts of metal
powders -- copper and silver and heaven only knows what else -- to
improve conductivity and to assure good compatibility with the copper
commutator drum in a motor.

Mark Kinsler