Alarm Clock

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Alarm Clock
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Pendulum Clock

• Isochronous motion
• Galileo (1583)
• Vincenzo (1649)
• Huygens (1675) Robert Hooke
• Regulating hair spring

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Pendulum Clock
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Huygens (1675)

• Regulating spiral

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Giovani di Dondi (1364)
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Electronic / Atomic

• pico-second
• Electronic
• quartz crystal produces a constant current when
  excited
• compressed to produce constant frequency
• Atomic
• Excitations of electrons in Caesium molecule

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Caesium Atomic clock