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The quartz tuning forks are made so accurate that they vibrate at 32,768 times per second plus or minus one six-hundredth. In order to get the forks tuned to this frequency, the designers first add some deposits of gold at the ends of the tines to lower the fork’s vibration frequency. Then a laser zaps tiny bits of the gold off until the desired frequency is reached. 
MECHANISM Mechanism
I. The quartz oscillator receives an electrical charge from an integrated circuit, which gets its power from the watch battery (or, in the case of a battery-less watch, the poser storage cell). The electricity makes the quartz vibrate, or oscillate, at the rate or 32,768 times per second. (Quartz crystals can be cut to vibrate at a huge range of frequencies. the bigger the piece, the slower it vibrates.)
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IV. If the watch is an analog model, the one-second impulses are transmitted to a stepping motor, which transforms them into mechanical pulses that drive a chain of gears and, ultimately, the watch hands. If it's a digital watch, the integrated circuit continues counting pulses as they add up to minutes, hours, and if the watch has a calendar display, days. In a digital watch the IC also provides the power to the display and contains the watch's setting functions. Because a digital watch has no gears or other moving parts, its construction is called "solid state."
unmigrated-wiki-markup
The basic formula for calculating the [fundamental frequency|http://en.wikipedia.org/wiki/Fundamental_frequency] calculating the fundamental frequency (f) of vibration of a [cantilever|http://en.wikipedia.org/wiki/Cantilever] as a function of its dimensions (quadratic of a cantilever as a function of its dimensions (quadratic cross-section) is:\[[1]\|http://en.wikipedia.org/wiki/Quartz_clock#cite_note-Itoh2002-1\] \\
where
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is: 
where
- 1.875 the smallest positive solution of cos(_x_)cosh(_x_) = \-1 \[[2]\|http://en.wikipedia.org/wiki/Quartz_clock#cite_note-2\]-1
- l is the length of the cantilever
- a is its thickness along the direction of motion
- E is its Young's modulus
- and ρ is its density
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A cantilever made of [quartz|http://en.wikipedia.org/wiki/Quartz] (_E_ = 10{^}11^ [N|http://en.wikipedia.org/wiki/Newton_(unit)]·m^−2^ = 100 [GPa|http://en.wikipedia.org/wiki/Pascal_(unit)] and _ρ_ = 2634 [kg|http://en.wikipedia.org/wiki/Kilogram]·m^−3^ \[[3]\|http://en.wikipedia.org/wiki/Quartz_clock#cite_note-3\]) with a length of 3 mm and a thickness of 0.3 mm has thus a fundamental frequency of around 33 kHz. The crystal is tuned to exactly 2{^}15^ = 32,768 Hz or runs at a slightly higher frequency with inhibition compensation (see below).
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\\made of quartz (E = 1011 N·m^−2^ = 100 GPa and ρ = 2634 kg·m^−3 with a length of 3 mm and a thickness of 0.3 mm has thus a fundamental frequency of around 33 kHz. The crystal is tuned to exactly 215 = 32,768 Hz or runs at a slightly higher frequency with inhibition compensation (see below).
REFERENCES
- Wikipedia +:http://en.wikipedia.org/wiki/Quartz_clock+
- http://www.capetowncorp.com/whatsnew/quartz.html
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