I really like Counting to a Billion by Che-Wei Wang. It uses an Arduino and a speech module to count up to 1 billion, and then it stops. The real question is, how long will it take? Will it even make it? I’m not sure, but it’s a cool experiment.
Counting to a Billion is a device created to fulfill the desire to count. The electronics consists of a microcontroller, a speech module, and a speaker powered by a rechargeable battery. There is no/off switch. The voice begins counting at one, two, three and continues counting up until it reaches one billion at which point in time it will stop.
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In the Maker Shed: Make: Arduino