Yes, in fact we did it last weekend in at USF's annual Engineering Expo.
However, we found that potatoes don't work for very long.  The phosphoric
acid in the potatoes quickly runs dry (within a matter of minutes).

As others have already suggested, lemons (or other citrus fruits) will last
a little bit longer.

Galvanized roofing nails are also a good source of zinc.  We cut a few solid
copper o-rings from the lab - they work great - but I'm not sure of their
general availability.

Just curious... what is your application?

Jen

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