203. ITP Stuff 995. Physical Computing

Coin Collection Switch

Did you ever have one of these?

They are fun to complete, but what do you get when you collect them all? NOTHING. No compliments. Well I made one for budding numismatists among us, with the sweet sweet neurological reward of a blue light turning on upon completion:

My original idea was to make a coin dish that “switched on” when conductive coins (i.e. pennies, but not quarters) were added. I made the coin bowl.
But It turns out that along with aluminum foil, all coins are conductive. This includes old “silver” dollars and Bahamian money.
So, important lesson, always test your components! Unit test ( i.e test them in an isolated environment) if possible. I suppose the same goes for debugging.
Instead we take advantage of their conductivity and the material immediately available on the floor: cardboard and tin foil!
Hopefully future fabrications will be less brutish. A little paint and labelling would certainly go a long way. But this will do for now.

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