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Servos don't work well in powered by 3.3VYou need to connect the power of the servo to 5V. If you are powering the arduino by USB, use to Vin pin to power the servo (the servo admits 3.3V in logic, so that is not a problem. You only need to change one cable).
Is it possible to do something like this but with one piezo? The problem with the piezo is that it generates its own voltage.
How fast can go the flash? 1 per second? 10 per second? Is it there a limit?