There are a surprising number of marble-based machines out there. Marbles work well in machines because they roll easily, have substantial weight, and are very consistent in diameter. Ivan Miranda was able to take advantage of those characteristics to build this amazing marble clock.
This project uses hundreds of marbles to display the time in numeric digits. To do so, the machine needs to roll specific marbles down tracks — white marbles for “on pixels” and black marbles for “off pixels.” When the time rolls over to the next minute, the clock releases those marbles back into a big hopper where they wait for the next cycle.
The machine carries marbles to the top of the track using an elevator mechanism. It picks up an entire row of marbles at once from the hopper, but their colors are random as far as the machine knows. So Miranda programmed an Arduino board to look at each marble in the row on the elevator. It uses infrared sensors to determine if each marble is black or white. It then triggers solenoids to eject any marbles that are the wrong color.
It is an inefficient trial-and-error process, but the machine can repeat that “lift and check” cycle as many times as it needs to until it sends all the right marbles down the appropriate tracks. Miranda has a few tweaks to make to increase reliability, but the clock is already a marvel!
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