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Engineering · Timekeeping & physics

Clockwork & Time

Tune a pendulum, hear an escapement tick, wind a mainspring and follow time from a quartz crystal to an atomic clock and GPS.

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The course

7 worlds · 28 lessons

World 1 · The Swinging Heart: Pendulums

FREEEvery clock needs something that repeats
  1. 01What every clock needsAn oscillator, a counter and a power source · 12 min
  2. 02The pendulum lawT = 2π√(L/g) and the seconds pendulum · 14 min
  3. 03Amplitude and the circular errorWhy wide swings run slow · 13 min
  4. 04Heat and gravity: why clocks driftedThermal expansion, latitude and compensation · 14 min

World 2 · Tick and Tock: Escapements

PROThe part that lets the clock count
  1. 01Anatomy of a mechanical clockFive jobs, one chain · 12 minPRO
  2. 02The escapementLock, impulse and the sound of ticking · 14 minPRO
  3. 03Balance wheel and hairspringA rotating oscillator for watches · 13 minPRO
  4. 04Why mechanical watches driftThe sources of error · 13 minPRO

World 3 · Gear Trains: Counting Time

PRORatios that turn a beat into hands
  1. 01Ratios from tick to handHow the hands get their speeds · 13 minPRO
  2. 02Designing a trainChoosing tooth numbers · 14 minPRO
  3. 03Mainspring, barrel and power reserveStoring energy in a coil · 12 minPRO
  4. 04Winding, setting and the date windowGeneral principles, not a manual · 12 minPRO

World 4 · Complications

PROGears that count days, months and moons
  1. 01Date and day-dateThe 31-tooth star wheel · 12 minPRO
  2. 02Annual and perpetual calendarsTeaching a watch about months and leap years · 14 minPRO
  3. 03Moonphase gearsA gear that counts about 29.5 days · 13 minPRO
  4. 04Chronograph, GMT and tourbillonWhat they do, and what they are worth · 13 minPRO

World 5 · Quartz and Beyond

PROA crystal that squeezes back
  1. 01A crystal that squeezes backPiezoelectricity and the 32 768 Hz fork · 13 minPRO
  2. 02How accurate is quartz?The temperature curve and ageing · 13 minPRO
  3. 03The quartz revolutionHow a crystal reshaped an industry · 11 minPRO
  4. 04Radio-controlled and eco-poweredTying a quartz clock to something better · 12 minPRO

World 6 · Atomic Time

PROWhen the second belongs to the atom
  1. 01Defining the secondNine billion ticks from a caesium atom · 12 minPRO
  2. 02How an atomic clock worksA feedback loop that locks to the atom · 14 minPRO
  3. 03Optical clocks and a future secondTicking with light · 13 minPRO
  4. 04UT1, UTC, TAI and leap secondsKeeping the atomic and the astronomical in step · 13 minPRO

World 7 · Time Across the Planet

PROFrom time zones to GPS
  1. 01Time zones and the 15-degree ruleWhy noon happens at different hours · 12 minPRO
  2. 02The longitude problemHow a clock found a ship · 14 minPRO
  3. 03How GPS finds you with clocksDistances from time, and why four satellites · 14 minPRO
  4. 04Relativity in your pocketWhy GPS satellite clocks are set wrong on purpose · 13 minPRO
Clockwork & Time — interactive 3D lab · Novareka