Dropping Marbles With Millisecond Accuracy

All eight version of the drop mechanism
The road to the perfect marble dropper

[Martin] of the band [Wintergatan] is on his third quest to build the ultimate musical marble machine, and that means dropping marbles with maximum reliability and precision timing. Working through several iterations, and returning to first principles, he engineered a marble gate that can drop marbles with a timing standard deviation of 0 ms.

[Wintergatan]’s first two machines, Marble Machine and Marble Machine X gained significant attention, but their complexity was their undoing. As it turns out, a Rube Goldberg machine that makes music has a lot of potential failure points, and both machines proved too temperamental for the live stage. The third version, Marble Machine XT (T for “touring”) needed to be re-engineered for simplicity and reliability to be practical on the road.

[Martin] broke the marble machine concept down to its key components, of which the marble drop gate is the most obvious. Using a pair of contact microphones to record the moment of release and impact, he can measure the timing with precision. The first design had a standard deviation of 3.91 ms, which is not nearly enough for us to detect by ear, but is not up to [Martin]’s standard for “tight music”. It used a clock-type escapement mechanism, where the wheel is the release gate. After reviewing his measurement software and compensating for drift between the software components of his setup, the measured standard deviation was reduced by 1 ms. Another breakthrough was to remove any guiding surfaces below the gate and let gravity do all the work. The 8th iteration proved to be the winner and used the escapement arm as the drop gate and wheel to hold back the queue of marbles.

Coming from an arts background, [Martin] had to learn a lot of engineering lessons the hard way. Looking at the videos on his YouTube channel, it seems like he is taking the lessons to heart, and we look forward to seeing the Marble Machine XT come to life.

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dinos-new-years-ball-drop

Build Your Own Mini Ball Drop For New Year’s Eve

[Dino] wanted to make this New Year’s celebration a bit more interesting, but he can’t make it to New York for the ball drop. Instead, he decided to make his own mini display in his workshop. Obviously he’s working with a slightly smaller budget than the folks at Times Square, but we think his display is pretty neat. If anything, [Dino] can at least guarantee that his New Year’s is 100% Seacrest-free.

The ball drop is made up of five ping pong balls, each backlit by a 10mm LED. The LEDs and ping pong balls were mounted on the electron gun from a broken oscilloscope, giving it a cool look. The balls are lit one at a time by an Arduino, which illuminates each one for 15 seconds while the final minute of 2011 is counted down. Once midnight hits, a flashing “2012” sign illuminates while Auld Lang Syne plays from a tiny speaker.

The musical part of this build is something that [Dino] spent a lot of time on. He thoroughly explains how he translated the song from sheet music into its digital form, a process that would be helpful for beginners to watch.

Continue reading to see how the display was built, and if you’re just antsy to see the ball drop in action, a short demo can be found at 12:13.

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New Year’s Eve Ball Drop In Your Kitchen

[Tech B.] hacked together a Ball Drop for New Year’s Eve using stuff he had lying around. The ball itself is an old Christmas ornament that he cut in half and filled with 14 LEDs and a 9V battery. He finished up that portion of the project by gluing the halves back together and adding a hole for the guide rod. The base is made of some cardboard boxes and hides an Arduino, a servo motor, an LCD screen, and the base for the vertical rod. When the last ten seconds of the year are counted down, a servo lowers the ball by unspooling some yarn that loops over the top of the rod. As the yarn is slowly dished out gravity pulls the ball toward its goal. We’ve embedded [Tech B.’s] demonstration video after the break.

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