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Auto-synchronization of metronomes

Submitted by on June 2, 2010 – 10:20 pm One Comment

This is a really interesting effect – 5 metronomes all placed on the same piece of material will eventually synchronize themselves ‘automagically’:

Very fascinating to watch, I even got a little rush when they all clicked.

Essentially, here’s how it works:

As each metronome comes to a stop & reverses direction at the top of it’s swing, it transfers energy to the platform. This energy transfers through the platform to each of the other metronomes.

The energy transferred to the platform from each metronome starts out of sync, but the waveforms of the energy interfere with each other, and at the location of each metronome you end up with negative or positive waveforms which in turn have an effect on the interference pattern. This keeps going until there is a balance – this balance is only achieved when all of the metronomes are in sync. The interference pattern is now a standing wave, which keeps the metronomes locked in phase.

When the whole contraption is put on the table, the table absorbs all the energy, reducing the interference patterns. You can see this phenomenon in many different types of oscillating systems, which can cause some major problems, especially with traffic on bridges and wind around buildings. You could also do the same thing with ticking watches, or even watches, which will eventually tick in time if places on a thin sheet of cardboard help up something like the cans in this video.

Of course if you’re a synth fan, you know that waves like these have harmonics, and the synchronization will also work with multiples of the fundamental frequency. You could presumably set some metronomes to half-speed to double-speed, and they would all tick in time, with different rhythms.

In cathode ray tubes (ie old TVs) this concept was used to lock the vertical and horizontal hold to keep the picture from “rolling”.

One Comment »

  • Bob says:

    When I first read the description of the interence I imagined that the ‘wave’ was in the vertical direction, but watching I was immediately aware that the waveform is in the horizontal axis. The asynchronicity of each metronome causes a shift along the horizontal axis of the board. Those metronomes that are swinging out of sync. will have an effect on the direction of the ‘roll’ of the board, which eventually cancels out asynchronous patterns of the rest. That’s why the board on the table top provides no cancelling effect, the board is fixed in the horizontal axis. Once on the cans the board is free to shift horizontally, allowing the cancellation of asynchronous movement. Notice that the greatest amplitude or ‘roll’ of the cans below the board is at the point of synchronicity.

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